NOTE: Trouble code detected. Also note: NO Injector pulse width. Also note RPM and throttle sensor voltage. I did NOT rev the engine. Also note vehicle speed.
HERE IS THE TROUBLE CODE DATA THAT FRAME ONLY!
╔══════════════════════════════════════╤ ═══════════════════════════════════ ═══╗
║VEHICLE TYPE: 1985 CHEVROLET │ENGINE TYPE: 5.7 Liter V8 ║
╟──────────────────────────────────────┼ ─────────────────────────────────── ───╢
║ECM MODE STATUS: DIAGNOSTIC │ECM PROM ID: 7806 ║
╠══════════════════════════════════════╧ ═══════════════════════════════════ ═══╣
║ TROUBLE CODE DISPLAY ║
╚═══════════════════════════════════════ ═══════════════════════════════════ ═══╝
Code Description
(42) ELECTRONIC SPARK TIMING MONITOR ERROR
(53) OVER VOLTAGE
(51) FAULTY OR IMPROPERLY INSTALLED ECM PROM
(45) RICH EXHAUST INDICATION
(44) LEAN EXHAUST INDICATION
Frame 3: vehicle died. Key still on.Note. Trouble code is gone.
══════════════════════════════════════╤═ ═══════════════════════════════════ ══╗
VEHICLE TYPE: 1985 CHEVROLET │ENGINE TYPE: 5.7 Liter V8 ║
──────────────────────────────────────┼─ ─────────────────────────────────── ──╢
ECM MODE STATUS: DIAGNOSTIC │ECM PROM ID: 7806 ║
══════════════════════════════════════╪═ ═══════════════════════════════════ ══╣
Engine Speed................ 0 RPM│ Closed Loop Status.......... Off ║
Vehicle Speed............... 23 MPH│ Fuel Mixture Status......... Lean ║
Coolant Temperature......... 169 F │ Battery Status.............. Norm ║
Manifold Air Temperature.... 124 F │ Torque Converter Clutch..... Off ║
Throttle Sensor Voltage..... 0.54 VDC│ Park/Neutral Switch......... Off ║
Oxygen Sensor Voltage....... 451 mV │ 3rd Gear Switch............. On ║
Oxygen Sensor Transitions... 0 # │ 4th Gear Switch............. On ║
Idle Air Position........... 0 # │ Power Steering Switch....... Off ║
Air Flow Rate............... 3 GPS│ Learn Control............... Off ║
Injector Pulse Width........ 0.0 mS │ A/C Request................. No ║
Spark Advance............... 0.0 DEG│ ............................ ║
EGR Duty Cycle.............. 0 % │ ............................ ║
Integrator.................. 128 # │ ............................ ║
Block Learn Multiplier...... 128 # │ ............................ ║
Spark Control Counts........ 0 # │ ............................ ║
══════════════════════════════════════╧═ ═══════════════════════════════════ ══╝
Next couple frames, nothing really happens different. I was slowing the vehicle to let the laptop hopefully record as much as possible.
Frame 4: Restarting …note pulse width and airflow.
VEHICLE TYPE: 1985 CHEVROLET │ENGINE TYPE: 5.7 Liter V8
──────────────────────────────────────┼─ ─────────────────────────────────── ──
ECM MODE STATUS: DIAGNOSTIC │ECM PROM ID: 7806
══════════════════════════════════════╪═ ═══════════════════════════════════ ══
Engine Speed................ 0 RPM│ Closed Loop Status.......... Off
Vehicle Speed............... 6 MPH│ Fuel Mixture Status......... Lean
Coolant Temperature......... 169 F │ Battery Status.............. Norm
Manifold Air Temperature.... 124 F │ Torque Converter Clutch..... Off
Throttle Sensor Voltage..... 0.54 VDC│ Park/Neutral Switch......... Off
Oxygen Sensor Voltage....... 451 mV │ 3rd Gear Switch............. On
Oxygen Sensor Transitions... 0 # │ 4th Gear Switch............. On
Idle Air Position........... 0 # │ Power Steering Switch....... Off
Air Flow Rate............... 3 GPS│ Learn Control............... Off
Injector Pulse Width........ 5.9 mS │ A/C Request................. No
Spark Advance............... 0.0 DEG│ ............................
EGR Duty Cycle.............. 0 % │ ............................
Integrator.................. 128 # │ ............................
Block Learn Multiplier...... 128 # │ ............................
Spark Control Counts........ 0 # │ ............................
Frame 5: Engine is restarting. Note airflow and pulse width change again. This is the next frame (packet) ECM which is slow delivered.
══════════════════════════════════════╤═ ═══════════════════════════════════ ══
VEHICLE TYPE: 1985 CHEVROLET │ENGINE TYPE: 5.7 Liter V8
──────────────────────────────────────┼─ ─────────────────────────────────── ──
ECM MODE STATUS: DIAGNOSTIC │ECM PROM ID: 7806
══════════════════════════════════════╪═ ═══════════════════════════════════ ══
Engine Speed................ 0 RPM│ Closed Loop Status.......... Off
Vehicle Speed............... 4 MPH│ Fuel Mixture Status......... Rich
Coolant Temperature......... 169 F │ Battery Status.............. Norm
Manifold Air Temperature.... 124 F │ Torque Converter Clutch..... Off
Throttle Sensor Voltage..... 0.56 VDC│ Park/Neutral Switch......... Off
Oxygen Sensor Voltage....... 451 mV │ 3rd Gear Switch............. On
Oxygen Sensor Transitions... 2 # │ 4th Gear Switch............. On
Idle Air Position........... 0 # │ Power Steering Switch....... Off
Air Flow Rate............... 12 GPS│ Learn Control............... Off
Injector Pulse Width........ 2.2 mS │ A/C Request................. No
Spark Advance............... 0.0 DEG│ ............................
EGR Duty Cycle.............. 0 % │ ............................
Integrator.................. 128 # │ ............................
Block Learn Multiplier...... 108 # │ ............................
Spark Control Counts........ 0 # │ ............................
SO, why the spark advance data? Why all the codes? What the heck is going on? IDEAS? The Diacom has NEVER displayed any spark advance. I always wondered why, but the car seemed to run fine. I attributed it to a C3 ECM, which is really what the 85 is.
I have replaced the ECM already with a reman AC Delco unit. Distributor cap, rotor, ignition module, ignition coil, plug wires, spark plugs are all AC Delco. ESC Module was replaced not too long ago - AC Delco. O2 sensor seems to be functioning - Bosch. MAF sensor is reman Cardone 2 days ago - had no effect on this problem other than allowing a restart without unplugging the MAF sensor.
I work in the automotive industry and troubleshoot this kind of thing all day on the phone, but this one has me stumped and I need help. I'm all ears.
Thanks in advance.
__________________
1985 Z-51. SK Speed ST-10 and self rebuilt OD unit.
So I put in a new AC Delco ignition switch. I tore the other one apart to look inside. It looked worn to me, but should have been functional. Who knows with an intermittent.
I thought I replace the ignition pickup coil just in case it was freaking out every once in awhile. I don't exactly recall, but just about when I had the distributor entirely back together I accidentally wiggled the wire to the condensor (capacitor). OOPS. It moved ALOT. The screw that holds it down looked tight, but it wasn't. I tested the condensor and it seemed to function. I pulled the module out and removed the condensor to check the underside for corrosion or anything like that. Everything looked fine so I restalled it and tightened the screw quite tight. I indexed all the reluctors loosening up the top pickup coil cover and by cutting up four small pieces of .008" brass feeler gauge and inserting them between the distributor shaft reluctor and the pickup reluctor every other one. That way it ended up being exactly evenly spaced all the way around. Turning the distributor by hand it does feel more pronounced now btw.
I must have worked on a smallblock Chevrolet before, because as soon as I hit the key she roared to life. I went to turn the distributor and got zapped barely touching a plug wire. Keep in mind, I've owned this car 12 years and that has never happened.
I think I found the problem. Throttle response seems very good and smooth.
I'm kind of mad I spent all that money, time, and aggravation and it turned out to be something so small. A 10 cent screw!
I learned: NEVER overlook the simple. Don't make it more complicated than it is. Keep it simple, Stupid.
Before I read to the bottom I was thinking - Ignition problem. Yeah. The ECM was losing the input "pulse" from the ESC module, probably because the ESC module wasn't getting a voltage from the pickup coil.
Stray voltage builds up (without the ground) and prevents the magnetic pickup from working. Simple problem, but darned hard to Find sometimes.
BTW - I've had these GM pickup coils where if the contact ring on the top touches the points of the rotating "star" on the distributor shaft at All then it would not work. Nothing. I've also had them where it could be touching so hard that it was grinding the thing Off, and it ran fine. Go figure.
__________________
'85 automatic coupe. 276K and counting, 330hp Crate Vortec heads, SDPP base manifold, BBK TB, true duals w/3 muffler setup (that's right - 3), driven daily year round - snow tires a Must!
OK. I have 4 LED lights wired up. Fuel pump reference signal at ECM, fuel injector pulse, MAF voltage and ignition power at the coil (ie anytime the ign key is on, I should have a light.)
When the car dies I can 100% tell you it is because the injector pulse quits. When the injector pulse quits the fuel pump reference signal quits after that. Sounds normal for the fuel pump reference signal to shutdown when the injector pulse stops.
However, the car will still die while driving. Last night, I noticed the light for 12V to the coil was blinking off and on but the car was running ok. THEN, get this. The car dies while going about 50mph. The injector pulse light and the fuel pump reference signal light are off. The MAF and ignition power at the coil lights were ON. I floored the gas pedal and the engine surged and came back to life ie. both the injector pulse light and the fuel pump ref signal light came back on.
Then when I was almost home the tach was displaying all kinds of weird RPMs. Mostly between 0 and 1500 rpm. It would actually display zero with the engine running.
What I don't understand is what is causing the injectors and fuel pump to shut down? The ignition module's distributor reference signal?
Here is what is predictable. If the car shuts off while in gear and moving, floor it and it will restart. Happened 3 times now.
The problem is it's losing fuel injector pulse. It has distributor reference signal, MAF signal, fuel pressure, and ignition. Just loses the injector pulse. WOT full throttle gives the pulse back and it will run good for a unpredicatable length of time.
Even when I got the car at 48k miles 12 years ago the throttle would bog like especially when cold like a carburetor without a whatever they call it - I forgot know. That deal that squirts fuel into the carb. I haven't worked on a car with a carb in years.
Should the throttle be more responsive? If I unplug the MAF the throttle response is absolutely horrible. It's works, but not well. Boggy.
Let me say first off that your skill level appears to be above mine, especially with electrical.
I did notice something that didn't look right in the first printout you show the PROM ID as 7806. The 85 is the only odd ball when they first started to go to tuned port....it uses a 1226870 chip usually referred to as the "870". In the 86 thru 89 they used the 1227165 chip. I don't know if the software you are using is picking up the chip ID or if you have to key it in and it then goes to a file for parameters. If the chip is incorrectly identified, it could cause the rest of your data to be crazy.
Just a wild A**ed thought about the computer.
Have you checked fuel pressure to be sure that it is constant?
PS, born and raised in the Evergreen State!!
John
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1985 Coup -ZZ4 balanced, LPE 74211 cam, AFR 180 heads, SuperRam base, runners & plenum, cut out air box, K & N filter, power coupler, 52MM TB, March pulleys, AFPR, Accel injectors, Walbro FP, 1.6 RR, chip by TJWONG, 160 stat, cut back plugs, 8.5MM MSD wires, Brute Thunder Coil, custom camber-brace,TRANSGO shift kit, 2400 stall converter, cross drilled rotors, SS brake lines, VBP camber rods, IAS Edelbrock shocks, custom crossover on exhaust, Magnflow cat, 3.07 gears, 13.2 @107.2 MPH in 1/4
Last edited by John A. Marker; 12-31-2009 at 12:15 AM.
I've tried both the original chip I put in storage back in 1997. Same difference.
I did find out that the ignition coil I put in must have the wires crossed in a way that seems wrong. The factory service manual pointed that out. The engine is much more responsive now. And with one plug lead off the coil it started arching towards the coil ground. So the polarity was messed up probably causing the issue I had with massive throttle response immediately after a fresh set of plugs, just to lose it rapidly.
Here is what I can replicated repeatedly. If the vehicle dies while driving it and in gear, floor the throttle and the fuel injectors start pulsing again. These are the old style pre-Multec fuel injectors. They just don't fail so that is not the issue.
What I need to understand is what is happening when I floor the throttle? It looks like the ECM is seeing high voltage on the TPS which is good. The maf seems to be working as well.
The hardest thing is I can't predict when it will happen long enough to diagnose it. If I just pull over to the side of the road, if I wait long enough the engine will "reset" itself. It could be a couple seconds or a couple minutes or as long as 1/2 hr.
Corvette Store
Look at this WIERD Diacom data from stalling problem
