help me check coil function
10-12-2013, 07:10 PM
#1
Safety Car
Thread Starter
help me check coil function
What is the best way to check for degraded coil function?
By best, I mean easy results. I suppose I could, in absence of any specs, just run a volt meter for readings and perhaps find one that is low and can that one.
But this plan is not sophisticated, and this engine is. So I ask for help.
I really need to know if there is any possible danger to the computers when blindly poking around in the ignition. Obviously, replacing parts without hard information is another reason to ask for help.
I am really happy with my stock motor, but it is high milage. It is not broken , just doesn't sound as smooth as I would like.
If this is something mechanical, or a design characteristic, I will let it ride. It idles fine , no big vibrations, but in listening, it is slightly uneven under load.
I suspect the coils. I have already replaced the wires and plugs, and as predicted by a helpful poster, the new spec smaller spark gap helped the idle , which was ok, but open for improvement.
The coils are fingered because a high skill corvette guy said the plugs wires and coils are the only thing that that go wrong with these engines. He confirmed the opinions I had been collecting since I started considering a used corvette.
Also, long ago, I was watching a TV show, two guys garage, and they had a well used C5 that showed coil degradation on a cool read out and replaced one coil. THis show also got me whipped up to replace all of my exhaust sensors , but a pro mechanic pointed out the pitfall of replacing working parts with parts that , while new, are of unknown function. Better to wait until failure, unless you want to bet money on quality control in 2013.
Same kind of deal with the coils I need some specs for quality control.
Perhaps you know of a better approach. I'm asking for paths to smoother sounding performance . I thank you in advance.
By best, I mean easy results. I suppose I could, in absence of any specs, just run a volt meter for readings and perhaps find one that is low and can that one.
But this plan is not sophisticated, and this engine is. So I ask for help.
I really need to know if there is any possible danger to the computers when blindly poking around in the ignition. Obviously, replacing parts without hard information is another reason to ask for help.
I am really happy with my stock motor, but it is high milage. It is not broken , just doesn't sound as smooth as I would like.
If this is something mechanical, or a design characteristic, I will let it ride. It idles fine , no big vibrations, but in listening, it is slightly uneven under load.
I suspect the coils. I have already replaced the wires and plugs, and as predicted by a helpful poster, the new spec smaller spark gap helped the idle , which was ok, but open for improvement.
The coils are fingered because a high skill corvette guy said the plugs wires and coils are the only thing that that go wrong with these engines. He confirmed the opinions I had been collecting since I started considering a used corvette.
Also, long ago, I was watching a TV show, two guys garage, and they had a well used C5 that showed coil degradation on a cool read out and replaced one coil. THis show also got me whipped up to replace all of my exhaust sensors , but a pro mechanic pointed out the pitfall of replacing working parts with parts that , while new, are of unknown function. Better to wait until failure, unless you want to bet money on quality control in 2013.
Same kind of deal with the coils I need some specs for quality control.
Perhaps you know of a better approach. I'm asking for paths to smoother sounding performance . I thank you in advance.
10-12-2013, 08:15 PM
#2
Tech Contributor
Member Since: Dec 1999
Location: Anthony TX
Posts: 32,736
Received 2,180 Likes
on
1,583 Posts
CI 6,7,8,9,11 Vet
St. Jude Donor '08
Blindly replacing parts is a big waste of time and money. There are ways to pinpoint defective components with out GUESSING.
Data Log the engine, Use a GM Tech 2 to do some basic testing,
Here are some thing to follow from your service manual.
Document ID# 1537547
2003 Chevrolet Corvette
--------------------------------------------------------------------------------
97-05 Vehicles with 4.8 5.3 5.7 and 6.0 Gen III V8 Engines and Misfires on One Bank - kw CEL diagnostics driveability DTC P0171 P0172 P0174 P0175 P0300 P0301 P0302 P0303 P0304 P0305 P0306 P0307 P0308 #PIP3056 - (Jul 12, 2004)
97 - 05 Vehicles with 4.8 5.3 5.7 and 6.0 Gen III V8 Engines and Misfires On One Bank
.
The following diagnosis might be helpful if the vehicle exhibits the described symptoms in the PI.
Condition/Concern:
Check Engine Light with a P0300 due to 2 - 4 cylinders misfiring on the same bank of the engine. DTCs P0171, P0172, P0174 or P0175 may also set for the misfiring bank.
Recommendation/Instructions:
If the published misfire diagnostic does not isolate the cause, perform the following suggestions as necessary:
Perform a fuel injector balance test for all 8 cylinders. If a fuel injector concern exists, it is possible to misfuel an entire bank of the engine, causing multiple cylinders on the same bank to misfire even though the root cause is a single fuel injector.
Inspect O2 sensor connections on the misfiring bank for corrosion or water intrusion. If water intrusion is found on the right bank, it may be due to the AC Evaporator Condensation dripping onto the O2 sensor harness. If this condition is found, reposition and shield the harness to prevent a repeat concern and repair the connections.
Check for excessive exhaust backpressure using the restricted exhaust diagnosis from SI.
Swap the Position 1 O2 sensors side to side to see if the misfires move to the other bank of the engine. If so, replace the O2 sensor.
.
Please follow this diagnosis process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed. If these steps do not resolve the condition, please contact GM TAC for further diagnostic assistance.
Models:
(00 - 05 Cadillac Escalade - C6 and K6) and (02 - 05 Chevrolet Avalanche - C1, C2 K1 and K2) and (99 - 05 Chevrolet Silverado - C1, C2 K1 and K2) and (00 - 05 Chevrolet Suburban - C1, C2, K1 and K2) and (00 - 05 Chevrolet Tahoe - C1 and K1) and (99 - 05 GMC Sierra C1, C2 K1 and K2) and (00 - 05 GMC Yukon - C1, C2, K1 and K2) and (03 - 05 Chevrolet Express G1, G2, G3, H1, H2 ) and (03 - 05 GMC Savana G1, G2, G3, H1, H2 ) and (04 - 05 Buick Rainier S1, T1 ) and (03 - 05 Chevrolet Trail Blazer EXT S1, T1 ) and (03 - 05 GMC Envoy XL XUV S1, T1 ) and (03 - 05 Hummer H2) and (04 - 05 Cadillac CTS-V DB) and (98 - 02 Chevrolet Camaro FB) and (97 - 04 Chevrolet Corvette YB) and (98 - 02 Pontiac Firebird FB) and (04 - 05 Pontiac GTO VB)
.
GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.
WE SUPPORT VOLUNTARY TECHNICIAN CERTIFICATION
© Copyright General Motors Corporation. All Rights Reserved.
--------------------------------------------------------------------------------
Document ID# 1537547
2003 Chevrolet Corvette
" Perform a fuel injector balance test for all 8 cylinders. "
This will tell you loads of info.
Document ID# 853321
2003 Chevrolet Corvette
--------------------------------------------------------------------------------
Rough, Unstable, or Incorrect Idle and Stalling
Inspections
Action
DEFINITION: Engine runs unevenly at idle. If severe, the engine or vehicle may shake. Engine idle speed may vary in RPM. Either condition may be severe enough to stall the engine.
Preliminary Inspections
Refer to Important Preliminary Inspections Before Starting in Symptoms - Engine Controls .
Search for bulletins.
Verify that the powertrain control module (PCM) grounds are clean, tight, and in the proper locations. Refer to Power and Grounding Component Views in Wiring Systems and Engine Controls Schematics .
Remove and inspect the air filter element for dirt or for restrictions. Refer to Air Cleaner Element Replacement . Replace as necessary.
Fuel System
Inspect the fuel injectors. Refer to Fuel Injector Coil Test , Fuel Injector Balance Test with Special Tool or Fuel Injector Balance Test with Tech 2 .
Inspect for incorrect fuel pressure. Refer to Fuel System Diagnosis .
Inspect for a restricted fuel filter. Refer to Fuel System Diagnosis .
Inspect for a contaminated fuel condition. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .
Inspect that each fuel injector harness is connected to the correct injector/cylinder. Relocate fuel injector harnesses as necessary.
Inspect for the following that may cause the engine to run rich:
Notice
Refer to Heated Oxygen and Oxygen Sensor Notice in Cautions and Notices.
Water intrusion in the HO2S connector
Engine oil contaminated by fuel
An EVAP canister purge condition
Incorrect fuel pressure--Refer to Fuel System Diagnosis .
A leaking fuel pressure regulator--Refer to Fuel System Diagnosis .
Leaking fuel injectors--Refer to Fuel System Diagnosis .
An inaccurate manifold absolute pressure (MAP) sensor
An inaccurate mass air flow (MAF) sensor
Blockage on the inlet screen of the MAF sensor
Vacuum hoses that are split, kinked, or improperly connected
An air intake duct that is collapsed or restricted
An air filter that is dirty or restricted--Refer to Air Cleaner Element Replacement .
Inspect for the following conditions that may cause the engine to run lean:
Notice
Refer to Heated Oxygen and Oxygen Sensor Notice in Cautions and Notices.
Water intrusion in the HO2S connector
An exhaust leak between the HO2S and the engine--Refer to Exhaust Leakage in Engine Exhaust.
Vacuum leaks
Incorrect fuel pressure--Refer to Fuel System Diagnosis .
Restricted fuel injectors--Refer to Fuel Injector Balance Test with Special Tool or Fuel Injector Balance Test with Tech 2 .
An inaccurate MAP sensor
An inaccurate MAF sensor
Fuel contamination--Refer to Alcohol/Contaminants-in-Fuel Diagnosis .
Vacuum hoses that are split, kinked, or improperly connected--Refer to Emission Hose Routing Diagram .
Sensor/System
Inspect the crankcase ventilation valve for proper operation. Place a finger over the inlet hole of the valve end several times. The valve should snap back. If not, replace the valve. Refer to Positive Crankcase Ventilation (PCV) Valve Replacement in Engine Mechanical.
Use a scan tool in order to monitor the knock sensor (KS) system for excessive spark retard activity.
Ignition System
Inspect for proper ignition voltage output with the J 26792 Spark Tester . Refer to Electronic Ignition (EI) System Diagnosis for procedure.
Remove spark plugs and check for the following:
Wet plugs
Cracks
Wear
Improper gap
Burned electrodes
Heavy deposits
Refer to Spark Plug Inspection .
An improper spark plug gap will cause a driveability problem. Refer to Spark Plug Inspection . Gap the spark plugs using a wire gauge gap tool. Refer to Spark Plug Replacement .
Determine the cause of the fouling before replacing the spark plugs.
Visually and physically inspect secondary ignition for the following:
Ignition wires arcing to ground
Ignition wires for proper routing
Soak the secondary ignition system with water from a spray bottle. Soaking the secondary ignition system may help locate damaged or deteriorated components. Look and listen for arcing or misfiring as you apply water. Monitor the Misfire Current Counters while driving the vehicle in the conditions that the misfire occurred. If a misfiring cylinder can be located, use the DTC P0300 table for diagnosis. Refer to DTC P0300 .
Inspect for loose ignition coil grounds. Refer to Electronic Ignition (EI) System Diagnosis .
Engine Mechanical
Inspect engine mechanical for the following:
Compression--Refer to Engine Compression Test in Engine Mechanical.
Sticking or leaking valves
Worn camshaft lobes
Valve timing
Bent push rods
Worn rocker arms
Broken valve springs
Excessive oil in combustion chamber or leaking valve seals. Refer to Oil Consumption Diagnosis in Engine Mechanical.
For incorrect basic engine parts. Inspect the following:
The camshaft--Refer to Crankshaft and Bearings Cleaning and Inspection in Engine Mechanical.
The cylinder heads--Refer to Cylinder Head Cleaning and Inspection in Engine Mechanical.
The pistons, etc.--Refer to Piston, Connecting Rod, and Bearings Cleaning and Inspection in Engine Mechanical.
Refer to Symptoms - Engine Mechanical in Engine Mechanical for diagnosis procedures.
Additional Inspections
Inspect the exhaust system for possible restrictions. Inspect for the following:
Inspect the exhaust system for damaged or collapsed pipes.
Inspect the mufflers for heat distress or possible internal failure.
Inspect for possible plugged catalytic converters. Refer to Restricted Exhaust in Engine Exhaust.
Electromagnetic interference (EMI) on the reference circuit can cause an engine miss condition. A scan tool can usually detect EMI by monitoring the engine RPM. A sudden increase in RPM with little change in actual engine RPM change indicates that EMI is present. If a problem exists, inspect routing of secondary ignition wires or high voltage components near the ignition control circuits.
Inspect the park neutral position (PNP) switch circuit. Refer to Park/Neutral Position Switch Adjustment
Inspect for faulty motor mounts. Refer to Engine Mount Inspection in Engine Mechanical.
Inspect the intake manifold and the exhaust manifold passages for casting flash. Refer to Intake Manifold Cleaning and Inspection or Exhaust Manifold Cleaning and Inspection in Engine Mechanical.
--------------------------------------------------------------------------------
Document ID# 853321
2003 Chevrolet Corvette
Next PAGE
Data Log the engine, Use a GM Tech 2 to do some basic testing,
Here are some thing to follow from your service manual.
Document ID# 1537547
2003 Chevrolet Corvette
--------------------------------------------------------------------------------
97-05 Vehicles with 4.8 5.3 5.7 and 6.0 Gen III V8 Engines and Misfires on One Bank - kw CEL diagnostics driveability DTC P0171 P0172 P0174 P0175 P0300 P0301 P0302 P0303 P0304 P0305 P0306 P0307 P0308 #PIP3056 - (Jul 12, 2004)
97 - 05 Vehicles with 4.8 5.3 5.7 and 6.0 Gen III V8 Engines and Misfires On One Bank
.
The following diagnosis might be helpful if the vehicle exhibits the described symptoms in the PI.
Condition/Concern:
Check Engine Light with a P0300 due to 2 - 4 cylinders misfiring on the same bank of the engine. DTCs P0171, P0172, P0174 or P0175 may also set for the misfiring bank.
Recommendation/Instructions:
If the published misfire diagnostic does not isolate the cause, perform the following suggestions as necessary:
Perform a fuel injector balance test for all 8 cylinders. If a fuel injector concern exists, it is possible to misfuel an entire bank of the engine, causing multiple cylinders on the same bank to misfire even though the root cause is a single fuel injector.
Inspect O2 sensor connections on the misfiring bank for corrosion or water intrusion. If water intrusion is found on the right bank, it may be due to the AC Evaporator Condensation dripping onto the O2 sensor harness. If this condition is found, reposition and shield the harness to prevent a repeat concern and repair the connections.
Check for excessive exhaust backpressure using the restricted exhaust diagnosis from SI.
Swap the Position 1 O2 sensors side to side to see if the misfires move to the other bank of the engine. If so, replace the O2 sensor.
.
Please follow this diagnosis process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed. If these steps do not resolve the condition, please contact GM TAC for further diagnostic assistance.
Models:
(00 - 05 Cadillac Escalade - C6 and K6) and (02 - 05 Chevrolet Avalanche - C1, C2 K1 and K2) and (99 - 05 Chevrolet Silverado - C1, C2 K1 and K2) and (00 - 05 Chevrolet Suburban - C1, C2, K1 and K2) and (00 - 05 Chevrolet Tahoe - C1 and K1) and (99 - 05 GMC Sierra C1, C2 K1 and K2) and (00 - 05 GMC Yukon - C1, C2, K1 and K2) and (03 - 05 Chevrolet Express G1, G2, G3, H1, H2 ) and (03 - 05 GMC Savana G1, G2, G3, H1, H2 ) and (04 - 05 Buick Rainier S1, T1 ) and (03 - 05 Chevrolet Trail Blazer EXT S1, T1 ) and (03 - 05 GMC Envoy XL XUV S1, T1 ) and (03 - 05 Hummer H2) and (04 - 05 Cadillac CTS-V DB) and (98 - 02 Chevrolet Camaro FB) and (97 - 04 Chevrolet Corvette YB) and (98 - 02 Pontiac Firebird FB) and (04 - 05 Pontiac GTO VB)
.
GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.
WE SUPPORT VOLUNTARY TECHNICIAN CERTIFICATION
© Copyright General Motors Corporation. All Rights Reserved.
--------------------------------------------------------------------------------
Document ID# 1537547
2003 Chevrolet Corvette
" Perform a fuel injector balance test for all 8 cylinders. "
This will tell you loads of info.
Document ID# 853321
2003 Chevrolet Corvette
--------------------------------------------------------------------------------
Rough, Unstable, or Incorrect Idle and Stalling
Inspections
Action
DEFINITION: Engine runs unevenly at idle. If severe, the engine or vehicle may shake. Engine idle speed may vary in RPM. Either condition may be severe enough to stall the engine.
Preliminary Inspections
Refer to Important Preliminary Inspections Before Starting in Symptoms - Engine Controls .
Search for bulletins.
Verify that the powertrain control module (PCM) grounds are clean, tight, and in the proper locations. Refer to Power and Grounding Component Views in Wiring Systems and Engine Controls Schematics .
Remove and inspect the air filter element for dirt or for restrictions. Refer to Air Cleaner Element Replacement . Replace as necessary.
Fuel System
Inspect the fuel injectors. Refer to Fuel Injector Coil Test , Fuel Injector Balance Test with Special Tool or Fuel Injector Balance Test with Tech 2 .
Inspect for incorrect fuel pressure. Refer to Fuel System Diagnosis .
Inspect for a restricted fuel filter. Refer to Fuel System Diagnosis .
Inspect for a contaminated fuel condition. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .
Inspect that each fuel injector harness is connected to the correct injector/cylinder. Relocate fuel injector harnesses as necessary.
Inspect for the following that may cause the engine to run rich:
Notice
Refer to Heated Oxygen and Oxygen Sensor Notice in Cautions and Notices.
Water intrusion in the HO2S connector
Engine oil contaminated by fuel
An EVAP canister purge condition
Incorrect fuel pressure--Refer to Fuel System Diagnosis .
A leaking fuel pressure regulator--Refer to Fuel System Diagnosis .
Leaking fuel injectors--Refer to Fuel System Diagnosis .
An inaccurate manifold absolute pressure (MAP) sensor
An inaccurate mass air flow (MAF) sensor
Blockage on the inlet screen of the MAF sensor
Vacuum hoses that are split, kinked, or improperly connected
An air intake duct that is collapsed or restricted
An air filter that is dirty or restricted--Refer to Air Cleaner Element Replacement .
Inspect for the following conditions that may cause the engine to run lean:
Notice
Refer to Heated Oxygen and Oxygen Sensor Notice in Cautions and Notices.
Water intrusion in the HO2S connector
An exhaust leak between the HO2S and the engine--Refer to Exhaust Leakage in Engine Exhaust.
Vacuum leaks
Incorrect fuel pressure--Refer to Fuel System Diagnosis .
Restricted fuel injectors--Refer to Fuel Injector Balance Test with Special Tool or Fuel Injector Balance Test with Tech 2 .
An inaccurate MAP sensor
An inaccurate MAF sensor
Fuel contamination--Refer to Alcohol/Contaminants-in-Fuel Diagnosis .
Vacuum hoses that are split, kinked, or improperly connected--Refer to Emission Hose Routing Diagram .
Sensor/System
Inspect the crankcase ventilation valve for proper operation. Place a finger over the inlet hole of the valve end several times. The valve should snap back. If not, replace the valve. Refer to Positive Crankcase Ventilation (PCV) Valve Replacement in Engine Mechanical.
Use a scan tool in order to monitor the knock sensor (KS) system for excessive spark retard activity.
Ignition System
Inspect for proper ignition voltage output with the J 26792 Spark Tester . Refer to Electronic Ignition (EI) System Diagnosis for procedure.
Remove spark plugs and check for the following:
Wet plugs
Cracks
Wear
Improper gap
Burned electrodes
Heavy deposits
Refer to Spark Plug Inspection .
An improper spark plug gap will cause a driveability problem. Refer to Spark Plug Inspection . Gap the spark plugs using a wire gauge gap tool. Refer to Spark Plug Replacement .
Determine the cause of the fouling before replacing the spark plugs.
Visually and physically inspect secondary ignition for the following:
Ignition wires arcing to ground
Ignition wires for proper routing
Soak the secondary ignition system with water from a spray bottle. Soaking the secondary ignition system may help locate damaged or deteriorated components. Look and listen for arcing or misfiring as you apply water. Monitor the Misfire Current Counters while driving the vehicle in the conditions that the misfire occurred. If a misfiring cylinder can be located, use the DTC P0300 table for diagnosis. Refer to DTC P0300 .
Inspect for loose ignition coil grounds. Refer to Electronic Ignition (EI) System Diagnosis .
Engine Mechanical
Inspect engine mechanical for the following:
Compression--Refer to Engine Compression Test in Engine Mechanical.
Sticking or leaking valves
Worn camshaft lobes
Valve timing
Bent push rods
Worn rocker arms
Broken valve springs
Excessive oil in combustion chamber or leaking valve seals. Refer to Oil Consumption Diagnosis in Engine Mechanical.
For incorrect basic engine parts. Inspect the following:
The camshaft--Refer to Crankshaft and Bearings Cleaning and Inspection in Engine Mechanical.
The cylinder heads--Refer to Cylinder Head Cleaning and Inspection in Engine Mechanical.
The pistons, etc.--Refer to Piston, Connecting Rod, and Bearings Cleaning and Inspection in Engine Mechanical.
Refer to Symptoms - Engine Mechanical in Engine Mechanical for diagnosis procedures.
Additional Inspections
Inspect the exhaust system for possible restrictions. Inspect for the following:
Inspect the exhaust system for damaged or collapsed pipes.
Inspect the mufflers for heat distress or possible internal failure.
Inspect for possible plugged catalytic converters. Refer to Restricted Exhaust in Engine Exhaust.
Electromagnetic interference (EMI) on the reference circuit can cause an engine miss condition. A scan tool can usually detect EMI by monitoring the engine RPM. A sudden increase in RPM with little change in actual engine RPM change indicates that EMI is present. If a problem exists, inspect routing of secondary ignition wires or high voltage components near the ignition control circuits.
Inspect the park neutral position (PNP) switch circuit. Refer to Park/Neutral Position Switch Adjustment
Inspect for faulty motor mounts. Refer to Engine Mount Inspection in Engine Mechanical.
Inspect the intake manifold and the exhaust manifold passages for casting flash. Refer to Intake Manifold Cleaning and Inspection or Exhaust Manifold Cleaning and Inspection in Engine Mechanical.
--------------------------------------------------------------------------------
Document ID# 853321
2003 Chevrolet Corvette
Next PAGE
10-12-2013, 08:18 PM
#3
Tech Contributor
Member Since: Dec 1999
Location: Anthony TX
Posts: 32,736
Received 2,180 Likes
on
1,583 Posts
CI 6,7,8,9,11 Vet
St. Jude Donor '08
Document ID# 851967
2003 Chevrolet Corvette
--------------------------------------------------------------------------------
Fuel Injector Coil Test
Circuit Description
The control module enables the appropriate fuel injector on the intake stroke for each cylinder. Ignition voltage is supplied directly to the fuel injectors. The control module controls each fuel injector by grounding the control circuit via a solid state device called a driver. A fuel injector coil winding resistance that is too high or too low will affect engine driveability. A fuel injector control circuit DTC may not set, but a misfire may be apparent. The fuel injector coil windings are affected by temperature. The resistance of the fuel injector coil windings will increase as the temperature of the fuel injector increases.
Diagnostic Aids
Monitoring the misfire current counters, or misfire graph, may help isolate the fuel injector that is causing the condition.
Operating the vehicle over a wide temperature range may help isolate the fuel injector that is causing the condition.
Perform the fuel injector coil test within the conditions of the customers concern. A fuel injector condition may only be apparent at a certain temperature, or under certain conditions.
Step
Action
Values
Yes
No
Schematic Reference: Engine Controls Schematics
Connector End View Reference: Powertrain Control Module (PCM) Connector End Views or Engine Controls Connector End Views
1
Did you perform the Diagnostic System Check-Engine Controls?
--
Go to Step 2
Go to Diagnostic System Check - Engine Controls
2
Observe the ECT sensor parameter with a scan tool.
Is the ECT sensor parameter within the specified range?
10-32°C (50-90°F)
Go to Step 3
Go to Step 4
3
Measure the resistance of each fuel injector with a DMM. Refer to Testing for Continuity in Wiring Systems.
Do any of the fuel injectors display a resistance outside the specified range?
11-14 ohms
Go to Step 6
Go to Fuel Injector Balance Test with Special Tool or Fuel Injector Balance Test with Tech 2
4
Measure the resistance of each fuel injector with a DMM. Refer to Testing for Continuity in Wiring Systems.
Record each fuel injector value.
Subtract the lowest resistance value from the highest resistance value.
Is the difference equal to, or less than, the specified value?
3 ohms
Go to Fuel Injector Balance Test with Special Tool or Fuel Injector Balance Test with Tech 2
Go to Step 5
5
Add all of the fuel injector resistance values, to obtain a total resistance value.
Divide the total resistance value by the number of fuel injectors, to obtain an average resistance value.
Subtract the lowest individual fuel injector resistance value from the average resistance value.
Compute the difference between the highest individual fuel injector resistance value and the average resistance value.
Replace the fuel injector that displays the greatest resistance difference, above or below the average. Refer to Fuel Injector Replacement .
Did you complete the replacement?
--
Go to Step 7
--
6
Replace the fuel injector or fuel injectors that are out of the specified range. Refer to Fuel Injector Replacement .
Did you complete the replacement?
11-14 ohms
Go to Step 7
--
7
Operate the system in order to verify the repair.
Did you correct the condition?
--
System OK
Go to Step 2
--------------------------------------------------------------------------------
Document ID# 851967
2003 Chevrolet Corvette
Document ID# 853331
2003 Chevrolet Corvette
--------------------------------------------------------------------------------
Backfire
Inspections
Actions
DEFINITION: Fuel ignites in the intake manifold or in the exhaust system, making a loud popping noise.
Preliminary Inspections
Refer to Important Preliminary Inspections Before Starting in Symptoms - Engine Controls .
Search for bulletins.
Verify that the powertrain control module (PCM) grounds are clean, tight, and in the proper locations. Refer to Power and Grounding Component Views in Wiring Systems and Engine Controls Schematics .
Fuel System
Inspect for incorrect fuel pressure. Refer to Fuel System Diagnosis .
Inspect for a restricted fuel filter. Refer to Fuel System Diagnosis .
Inspect for a contaminated fuel condition. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .
Inspect the fuel injectors. Refer to Fuel Injector Coil Test .
Verify that each injector harness is connected to the correct injector or cylinder. Relocate injector harnesses as necessary.
Sensor/System
Inspect the secondary air injection (AIR) system.
Inspect the air intake system and crankcase for air leaks.
Inspect the crankcase ventilation valve for proper operation. Place a finger over the inlet hole in the valve end several times. The valve should snap back. If not, replace the valve. Refer to Positive Crankcase Ventilation (PCV) Valve Replacement in Engine Mechanical.
Inspect for an inaccurate speedometer. Refer to Speedometer and/or Odometer Inaccurate or Inoperative in Instrument Panel, Gages, and Console.
Use a scan tool in order to monitor the knock sensor (KS) system for excessive spark retard activity. Refer to Knock Sensor (KS) System Description .
Ignition System
Inspect for proper ignition voltage output with J 26792 Spark Tester .
Remove spark plugs and inspect for the following:
Wet plugs
Cracks
Wear
Improper gap
Burned electrodes
Heavy deposits
Refer to Spark Plug Inspection .
An improper spark plug gap will cause a driveability problem. Refer to Spark Plug Inspection . Gap the spark plugs using a wire gauge gap tool . Refer to Spark Plug Replacement .
Determine the cause of the fouling before replacing the spark plugs. Refer to Spark Plug Inspection for diagnosis.
Visually and physically inspect secondary ignition for the following:
Ignition wires arcing to ground
Ignition coils arcing to ground
Soak the secondary ignition system with water from a spray bottle. Soaking the secondary ignition system may help locate damaged or deteriorated components. Look and listen for arcing or misfiring as you apply the water.
Monitor the Misfire Current Counters while driving the vehicle in the conditions that the misfire occurred. If a misfiring cylinder can be located, use the DTC P0300 table for diagnosis. Refer to DTC P0300
Inspect for loose ignition coil grounds. Refer to Electronic Ignition (EI) System Diagnosis .
Engine Cooling System
Inspect the engine coolant level for being low. Refer to Loss of Coolant in Engine Cooling.
Inspect the engine thermostat for proper operation and for the correct heat range. Refer to Thermostat Diagnosis in Engine Cooling.
Engine Mechanical
Inspect engine mechanical for the following:
Compression--Refer to Engine Compression Test in Engine Mechanical.
Sticking or leaking valves
Worn camshaft lobes
Valve timing
Bent push rods
Worn rocker arms
Broken valve springs
Excessive oil in combustion chamber or leaking valve seals. Refer to Oil Consumption Diagnosis in Engine Mechanical.
For incorrect basic engine parts. Inspect the following:
The camshaft--Refer to Crankshaft and Bearings Cleaning and Inspection in Engine Mechanical.
The cylinder heads--Refer to Cylinder Head Cleaning and Inspection in Engine Mechanical.
The pistons, etc.--Refer to Piston, Connecting Rod, and Bearings Cleaning and Inspection in Engine Mechanical.
Refer to Symptoms - Engine Mechanical in Engine Mechanical for diagnosis procedures.
Additional Inspections
Visually and physically inspect the vacuum hoses for splits, kinks, and proper connections and routing as shown on the Vehicle Emission Control Information label. Refer to Emission Hose Routing Diagram .
Inspect the intake manifold and the exhaust manifold passages for casting flash. Refer to Intake Manifold Cleaning and Inspection or Exhaust Manifold Cleaning and Inspection in Engine Mechanical.
Inspect the transmission torque converter clutch (TCC) operation. The scan tool should indicate an RPM drop when the TCC is commanded ON. Refer to Diagnostic System Check - Automatic Transmission in Automatic Transmission-4L60-E.
Inspect the exhaust system for possible restrictions. Inspect the following:
Inspect the exhaust system for damaged or collapsed pipes.
Inspect the mufflers for heat distress or possible internal failure.
Inspect for possible plugged catalytic converters. Refer to Restricted Exhaust in Engine Exhaust.
Electromagnetic interference (EMI) on the reference circuit can cause an engine miss condition. A scan tool can usually detect EMI by monitoring the engine RPM. A sudden increase in RPM with little change in actual engine RPM change may indicate that EMI is present. If a problem exists, inspect for high voltage components near the ignition control circuits.
Inspect the park/neutral position (PNP) switch operation. Refer to Park/Neutral Position Switch Adjustment in Automatic Transmission-4L60-E.
--------------------------------------------------------------------------------
Document ID# 853331
2003 Chevrolet Corvette
2003 Chevrolet Corvette
--------------------------------------------------------------------------------
Fuel Injector Coil Test
Circuit Description
The control module enables the appropriate fuel injector on the intake stroke for each cylinder. Ignition voltage is supplied directly to the fuel injectors. The control module controls each fuel injector by grounding the control circuit via a solid state device called a driver. A fuel injector coil winding resistance that is too high or too low will affect engine driveability. A fuel injector control circuit DTC may not set, but a misfire may be apparent. The fuel injector coil windings are affected by temperature. The resistance of the fuel injector coil windings will increase as the temperature of the fuel injector increases.
Diagnostic Aids
Monitoring the misfire current counters, or misfire graph, may help isolate the fuel injector that is causing the condition.
Operating the vehicle over a wide temperature range may help isolate the fuel injector that is causing the condition.
Perform the fuel injector coil test within the conditions of the customers concern. A fuel injector condition may only be apparent at a certain temperature, or under certain conditions.
Step
Action
Values
Yes
No
Schematic Reference: Engine Controls Schematics
Connector End View Reference: Powertrain Control Module (PCM) Connector End Views or Engine Controls Connector End Views
1
Did you perform the Diagnostic System Check-Engine Controls?
--
Go to Step 2
Go to Diagnostic System Check - Engine Controls
2
Observe the ECT sensor parameter with a scan tool.
Is the ECT sensor parameter within the specified range?
10-32°C (50-90°F)
Go to Step 3
Go to Step 4
3
Measure the resistance of each fuel injector with a DMM. Refer to Testing for Continuity in Wiring Systems.
Do any of the fuel injectors display a resistance outside the specified range?
11-14 ohms
Go to Step 6
Go to Fuel Injector Balance Test with Special Tool or Fuel Injector Balance Test with Tech 2
4
Measure the resistance of each fuel injector with a DMM. Refer to Testing for Continuity in Wiring Systems.
Record each fuel injector value.
Subtract the lowest resistance value from the highest resistance value.
Is the difference equal to, or less than, the specified value?
3 ohms
Go to Fuel Injector Balance Test with Special Tool or Fuel Injector Balance Test with Tech 2
Go to Step 5
5
Add all of the fuel injector resistance values, to obtain a total resistance value.
Divide the total resistance value by the number of fuel injectors, to obtain an average resistance value.
Subtract the lowest individual fuel injector resistance value from the average resistance value.
Compute the difference between the highest individual fuel injector resistance value and the average resistance value.
Replace the fuel injector that displays the greatest resistance difference, above or below the average. Refer to Fuel Injector Replacement .
Did you complete the replacement?
--
Go to Step 7
--
6
Replace the fuel injector or fuel injectors that are out of the specified range. Refer to Fuel Injector Replacement .
Did you complete the replacement?
11-14 ohms
Go to Step 7
--
7
Operate the system in order to verify the repair.
Did you correct the condition?
--
System OK
Go to Step 2
--------------------------------------------------------------------------------
Document ID# 851967
2003 Chevrolet Corvette
Document ID# 853331
2003 Chevrolet Corvette
--------------------------------------------------------------------------------
Backfire
Inspections
Actions
DEFINITION: Fuel ignites in the intake manifold or in the exhaust system, making a loud popping noise.
Preliminary Inspections
Refer to Important Preliminary Inspections Before Starting in Symptoms - Engine Controls .
Search for bulletins.
Verify that the powertrain control module (PCM) grounds are clean, tight, and in the proper locations. Refer to Power and Grounding Component Views in Wiring Systems and Engine Controls Schematics .
Fuel System
Inspect for incorrect fuel pressure. Refer to Fuel System Diagnosis .
Inspect for a restricted fuel filter. Refer to Fuel System Diagnosis .
Inspect for a contaminated fuel condition. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .
Inspect the fuel injectors. Refer to Fuel Injector Coil Test .
Verify that each injector harness is connected to the correct injector or cylinder. Relocate injector harnesses as necessary.
Sensor/System
Inspect the secondary air injection (AIR) system.
Inspect the air intake system and crankcase for air leaks.
Inspect the crankcase ventilation valve for proper operation. Place a finger over the inlet hole in the valve end several times. The valve should snap back. If not, replace the valve. Refer to Positive Crankcase Ventilation (PCV) Valve Replacement in Engine Mechanical.
Inspect for an inaccurate speedometer. Refer to Speedometer and/or Odometer Inaccurate or Inoperative in Instrument Panel, Gages, and Console.
Use a scan tool in order to monitor the knock sensor (KS) system for excessive spark retard activity. Refer to Knock Sensor (KS) System Description .
Ignition System
Inspect for proper ignition voltage output with J 26792 Spark Tester .
Remove spark plugs and inspect for the following:
Wet plugs
Cracks
Wear
Improper gap
Burned electrodes
Heavy deposits
Refer to Spark Plug Inspection .
An improper spark plug gap will cause a driveability problem. Refer to Spark Plug Inspection . Gap the spark plugs using a wire gauge gap tool . Refer to Spark Plug Replacement .
Determine the cause of the fouling before replacing the spark plugs. Refer to Spark Plug Inspection for diagnosis.
Visually and physically inspect secondary ignition for the following:
Ignition wires arcing to ground
Ignition coils arcing to ground
Soak the secondary ignition system with water from a spray bottle. Soaking the secondary ignition system may help locate damaged or deteriorated components. Look and listen for arcing or misfiring as you apply the water.
Monitor the Misfire Current Counters while driving the vehicle in the conditions that the misfire occurred. If a misfiring cylinder can be located, use the DTC P0300 table for diagnosis. Refer to DTC P0300
Inspect for loose ignition coil grounds. Refer to Electronic Ignition (EI) System Diagnosis .
Engine Cooling System
Inspect the engine coolant level for being low. Refer to Loss of Coolant in Engine Cooling.
Inspect the engine thermostat for proper operation and for the correct heat range. Refer to Thermostat Diagnosis in Engine Cooling.
Engine Mechanical
Inspect engine mechanical for the following:
Compression--Refer to Engine Compression Test in Engine Mechanical.
Sticking or leaking valves
Worn camshaft lobes
Valve timing
Bent push rods
Worn rocker arms
Broken valve springs
Excessive oil in combustion chamber or leaking valve seals. Refer to Oil Consumption Diagnosis in Engine Mechanical.
For incorrect basic engine parts. Inspect the following:
The camshaft--Refer to Crankshaft and Bearings Cleaning and Inspection in Engine Mechanical.
The cylinder heads--Refer to Cylinder Head Cleaning and Inspection in Engine Mechanical.
The pistons, etc.--Refer to Piston, Connecting Rod, and Bearings Cleaning and Inspection in Engine Mechanical.
Refer to Symptoms - Engine Mechanical in Engine Mechanical for diagnosis procedures.
Additional Inspections
Visually and physically inspect the vacuum hoses for splits, kinks, and proper connections and routing as shown on the Vehicle Emission Control Information label. Refer to Emission Hose Routing Diagram .
Inspect the intake manifold and the exhaust manifold passages for casting flash. Refer to Intake Manifold Cleaning and Inspection or Exhaust Manifold Cleaning and Inspection in Engine Mechanical.
Inspect the transmission torque converter clutch (TCC) operation. The scan tool should indicate an RPM drop when the TCC is commanded ON. Refer to Diagnostic System Check - Automatic Transmission in Automatic Transmission-4L60-E.
Inspect the exhaust system for possible restrictions. Inspect the following:
Inspect the exhaust system for damaged or collapsed pipes.
Inspect the mufflers for heat distress or possible internal failure.
Inspect for possible plugged catalytic converters. Refer to Restricted Exhaust in Engine Exhaust.
Electromagnetic interference (EMI) on the reference circuit can cause an engine miss condition. A scan tool can usually detect EMI by monitoring the engine RPM. A sudden increase in RPM with little change in actual engine RPM change may indicate that EMI is present. If a problem exists, inspect for high voltage components near the ignition control circuits.
Inspect the park/neutral position (PNP) switch operation. Refer to Park/Neutral Position Switch Adjustment in Automatic Transmission-4L60-E.
--------------------------------------------------------------------------------
Document ID# 853331
2003 Chevrolet Corvette
10-12-2013, 08:20 PM
#4
Tech Contributor
Member Since: Dec 1999
Location: Anthony TX
Posts: 32,736
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CI 6,7,8,9,11 Vet
St. Jude Donor '08
Here are the COIL TEST that you desire:
Document ID# 835670
2003 Chevrolet Corvette
--------------------------------------------------------------------------------
Electronic Ignition (EI) System Diagnosis
Circuit Description
The electronic ignition system uses an individual ignition coil for each cylinder. The powertrain control module (PCM) controls the ignition operation through eight individual ignition control (IC) circuits. Each bank of four ignition coils is connected to the PCM, power, or ground by the following circuits:
Low reference
Chassis ground
Ignition 1 voltage
The appropriate IC circuit
The PCM triggers an ignition coil by grounding the appropriate IC circuit using information from the crankshaft position (CKP) and camshaft position (CMP) sensors.
Test Description
The number below refers to the step number on the diagnostic table.
Monitoring the misfire current counters determines if a fault is present.
Step
Action
Value(s)
Yes
No
Schematic Reference: Engine Controls Schematics
Connector End View Reference: Powertrain Control Module (PCM) Connector End Views or Engine Controls Connector End Views
1
Did you perform the Diagnostic System Check-Engine Controls?
--
Go to Step 2
Go to Diagnostic System Check - Engine Controls
2
Crank the engine.
Observe the engine speed parameter with a scan tool.
Does the scan tool display engine RPM?
--
Go to Step 3
Go to Step 13
3
Is DTC P0335, P0336, or P0351-P0358 also set?
--
Go to Diagnostic Trouble Code (DTC) List
Go to Step 4
4
Idle the engine.
Observe the misfire current counters on the scan tool.
Does the scan tool display any misfire current counters incrementing?
--
Go to Step 5
Go to Intermittent Conditions
5
Turn OFF the ignition.
Remove the fuel pump relay.
Test for spark at each affected cylinder with the J 26792 Spark Tester.
Do you have bright blue spark on the cylinders?
--
Go to Step 6
Go to Step 7
6
Remove the spark plugs.
Inspect the spark plugs for any abnormal conditions or damage. Refer to Spark Plug Inspection .
Are the spark plugs in good condition?
--
System OK
Go to Step 22
7
Measure the spark plug wire resistance. Refer to Spark Plug Wire Inspection .
Is the resistance more than the specified value?
700 ohms/ft
Go to Step 23
Go to Step 8
8
Turn OFF the ignition.
Disconnect the affected ignition coil.
Turn ON the ignition, with the engine OFF.
Probe the ignition voltage circuit of the affected ignition coil with a test lamp that is connected to a good ground. Refer to Probing Electrical Connectors in Wiring Systems.
Does the test lamp illuminate?
--
Go to Step 9
Go to Step 19
9
Probe the ignition voltage circuit at the affected ignition coil with a test lamp that is connected to the ground circuit of the affected ignition coil. Refer to Probing Electrical Connectors in Wiring Systems.
Does the test lamp illuminate?
--
Go to Step 10
Go to Step 20
10
Probe the ignition voltage circuit at the affected ignition coil with a test lamp that is connected to the low reference circuit of the affected ignition coil. Refer to Probing Electrical Connectors in Wiring Systems.
Does the test lamp illuminate?
--
Go to Step 11
Go to Step 15
11
Measure the resistance of the ignition voltage circuit of the affected ignition coil from the fuse that supplies ignition voltage to the affected ignition coil to the harness connector of the affected ignition coil.
Is the resistance less than the specified value?
3 ohms
Go to Step 12
Go to Step 19
12
Measure the resistance of the ground circuit of the affected ignition coil from the harness connector of the affected ignition coil to a good ground.
Is the resistance less than the specified value?
3 ohms
Go to Step 17
Go to Step 20
13
Turn ON the ignition, with the engine OFF.
Disconnect the crankshaft position (CKP) sensor.
Measure the voltage from the CKP sensor 12-volt reference circuit to a good ground with the DMM.
Compare the measured voltage with the system voltage.
Is the difference in the voltage more than the specified value?
0.5 V
Go to Step 14
Go to Step 16
14
Test for a short to ground in the CKP 12-volt reference circuit or the camshaft position (CMP) sensor 12-volt reference circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
--
Go to Step 26
Go to Step 18
15
Test the low reference circuit of the ignition coil for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
--
Go to Step 26
Go to Step 18
16
Test for shorted terminals and poor connections at the CKP sensor. Refer to Testing for Intermittent and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?
--
Go to Step 26
Go to Step 21
17
Test for an intermittent and for a poor connections at the ignition coil. Refer to Testing for Intermittent and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?
--
Go to Step 26
Go to Step 24
18
Test for shorted terminals and for poor connections at the powertrain control module (PCM). Refer to Testing for Intermittent and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?
--
Go to Step 26
Go to Step 25
19
Repair the ignition voltage circuit of the affected ignition coil for one of the following conditions:
An open
High resistance
A short to ground
Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?
--
Go to Step 26
--
20
Repair the ground circuit of the affected ignition coil for one of the following conditions:
An open
High resistance
Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?
--
Go to Step 26
--
21
Replace the CKP sensor. Refer to Crankshaft Position (CKP) Sensor Replacement .
Did you complete the replacement?
--
Go to Step 26
--
22
Replace the spark plug. Refer to Spark Plug Replacement .
Did you complete the replacement?
--
Go to Step 26
--
23
Replace the spark plug wire. Refer to Spark Plug Wire Replacement .
Did you complete the replacement?
--
Go to Step 26
--
24
Replace the ignition coil. Refer to Ignition Coil(s) Replacement .
Did you complete the replacement?
--
Go to Step 26
--
25
Replace the PCM. Refer to Powertrain Control Module (PCM) Replacement .
Did you complete the replacement?
--
Go to Step 26
--
26
Turn OFF the engine for 30 seconds.
Start the engine and operate the vehicle.
Observe the vehicle performance and driveability.
Does the vehicle operate normally?
--
System OK
Go to Step 3
--------------------------------------------------------------------------------
Document ID# 835670
2003 Chevrolet Corvette
Document ID# 835670
2003 Chevrolet Corvette
--------------------------------------------------------------------------------
Electronic Ignition (EI) System Diagnosis
Circuit Description
The electronic ignition system uses an individual ignition coil for each cylinder. The powertrain control module (PCM) controls the ignition operation through eight individual ignition control (IC) circuits. Each bank of four ignition coils is connected to the PCM, power, or ground by the following circuits:
Low reference
Chassis ground
Ignition 1 voltage
The appropriate IC circuit
The PCM triggers an ignition coil by grounding the appropriate IC circuit using information from the crankshaft position (CKP) and camshaft position (CMP) sensors.
Test Description
The number below refers to the step number on the diagnostic table.
Monitoring the misfire current counters determines if a fault is present.
Step
Action
Value(s)
Yes
No
Schematic Reference: Engine Controls Schematics
Connector End View Reference: Powertrain Control Module (PCM) Connector End Views or Engine Controls Connector End Views
1
Did you perform the Diagnostic System Check-Engine Controls?
--
Go to Step 2
Go to Diagnostic System Check - Engine Controls
2
Crank the engine.
Observe the engine speed parameter with a scan tool.
Does the scan tool display engine RPM?
--
Go to Step 3
Go to Step 13
3
Is DTC P0335, P0336, or P0351-P0358 also set?
--
Go to Diagnostic Trouble Code (DTC) List
Go to Step 4
4
Idle the engine.
Observe the misfire current counters on the scan tool.
Does the scan tool display any misfire current counters incrementing?
--
Go to Step 5
Go to Intermittent Conditions
5
Turn OFF the ignition.
Remove the fuel pump relay.
Test for spark at each affected cylinder with the J 26792 Spark Tester.
Do you have bright blue spark on the cylinders?
--
Go to Step 6
Go to Step 7
6
Remove the spark plugs.
Inspect the spark plugs for any abnormal conditions or damage. Refer to Spark Plug Inspection .
Are the spark plugs in good condition?
--
System OK
Go to Step 22
7
Measure the spark plug wire resistance. Refer to Spark Plug Wire Inspection .
Is the resistance more than the specified value?
700 ohms/ft
Go to Step 23
Go to Step 8
8
Turn OFF the ignition.
Disconnect the affected ignition coil.
Turn ON the ignition, with the engine OFF.
Probe the ignition voltage circuit of the affected ignition coil with a test lamp that is connected to a good ground. Refer to Probing Electrical Connectors in Wiring Systems.
Does the test lamp illuminate?
--
Go to Step 9
Go to Step 19
9
Probe the ignition voltage circuit at the affected ignition coil with a test lamp that is connected to the ground circuit of the affected ignition coil. Refer to Probing Electrical Connectors in Wiring Systems.
Does the test lamp illuminate?
--
Go to Step 10
Go to Step 20
10
Probe the ignition voltage circuit at the affected ignition coil with a test lamp that is connected to the low reference circuit of the affected ignition coil. Refer to Probing Electrical Connectors in Wiring Systems.
Does the test lamp illuminate?
--
Go to Step 11
Go to Step 15
11
Measure the resistance of the ignition voltage circuit of the affected ignition coil from the fuse that supplies ignition voltage to the affected ignition coil to the harness connector of the affected ignition coil.
Is the resistance less than the specified value?
3 ohms
Go to Step 12
Go to Step 19
12
Measure the resistance of the ground circuit of the affected ignition coil from the harness connector of the affected ignition coil to a good ground.
Is the resistance less than the specified value?
3 ohms
Go to Step 17
Go to Step 20
13
Turn ON the ignition, with the engine OFF.
Disconnect the crankshaft position (CKP) sensor.
Measure the voltage from the CKP sensor 12-volt reference circuit to a good ground with the DMM.
Compare the measured voltage with the system voltage.
Is the difference in the voltage more than the specified value?
0.5 V
Go to Step 14
Go to Step 16
14
Test for a short to ground in the CKP 12-volt reference circuit or the camshaft position (CMP) sensor 12-volt reference circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
--
Go to Step 26
Go to Step 18
15
Test the low reference circuit of the ignition coil for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
--
Go to Step 26
Go to Step 18
16
Test for shorted terminals and poor connections at the CKP sensor. Refer to Testing for Intermittent and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?
--
Go to Step 26
Go to Step 21
17
Test for an intermittent and for a poor connections at the ignition coil. Refer to Testing for Intermittent and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?
--
Go to Step 26
Go to Step 24
18
Test for shorted terminals and for poor connections at the powertrain control module (PCM). Refer to Testing for Intermittent and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?
--
Go to Step 26
Go to Step 25
19
Repair the ignition voltage circuit of the affected ignition coil for one of the following conditions:
An open
High resistance
A short to ground
Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?
--
Go to Step 26
--
20
Repair the ground circuit of the affected ignition coil for one of the following conditions:
An open
High resistance
Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?
--
Go to Step 26
--
21
Replace the CKP sensor. Refer to Crankshaft Position (CKP) Sensor Replacement .
Did you complete the replacement?
--
Go to Step 26
--
22
Replace the spark plug. Refer to Spark Plug Replacement .
Did you complete the replacement?
--
Go to Step 26
--
23
Replace the spark plug wire. Refer to Spark Plug Wire Replacement .
Did you complete the replacement?
--
Go to Step 26
--
24
Replace the ignition coil. Refer to Ignition Coil(s) Replacement .
Did you complete the replacement?
--
Go to Step 26
--
25
Replace the PCM. Refer to Powertrain Control Module (PCM) Replacement .
Did you complete the replacement?
--
Go to Step 26
--
26
Turn OFF the engine for 30 seconds.
Start the engine and operate the vehicle.
Observe the vehicle performance and driveability.
Does the vehicle operate normally?
--
System OK
Go to Step 3
--------------------------------------------------------------------------------
Document ID# 835670
2003 Chevrolet Corvette
10-14-2013, 04:10 AM
#6
Safety Car
Thread Starter
I guess that about covers it.
Wow, and to think I was going to retract the question because I found the resistance values for both sides of the coil from a post here, but I had to use an outside search engine.
I was glad to get the detailed information, and also glad as I read on , that my idle is consistent, it doesn't seem like fuel. Just a little tweak in the song was seen as possible. And since my long held suspicions of where to look first for weaknesses were confirmed by a more skilled owner, all I needed were some numbers.
I guess I shouldn't have worried about stressing the computer by screwing around with the coils. I never would have thought of spraying water on the stuff to check integrity. Glad I asked, that was new, as were a few of the other details. Man, I am glad I choose a used car without a lot of problems. Just reading that stuff give me the *******.
I was glad to get the detailed information, and also glad as I read on , that my idle is consistent, it doesn't seem like fuel. Just a little tweak in the song was seen as possible. And since my long held suspicions of where to look first for weaknesses were confirmed by a more skilled owner, all I needed were some numbers.
I guess I shouldn't have worried about stressing the computer by screwing around with the coils. I never would have thought of spraying water on the stuff to check integrity. Glad I asked, that was new, as were a few of the other details. Man, I am glad I choose a used car without a lot of problems. Just reading that stuff give me the *******.