slpws6

2000 frc 6 speed manual
Cleaned Maf and throttle body the problem is still there
If I give car 3/4 throttle or wot it seems to fall on its face in any gear until I get to 2500 rpm then the car completely comes to life. Does it when engine is cold or hot. Seems to be worse under load like going up a hill at low rpm

Thanks

DooDooBear1999

Is the car tuned?

slpws6

Yes it is

DooDooBear1999

Everything that comes to mind (fuel filter, plug, plug wire, injector) wouldn't explain why it would stumble and then come on with the power. If it was any of those, I'd think that it would affect the car up through the RPM range, not just <2500rpm. I think it would be something in the tune. Just an idea. Someone with loads of experience should find this thread soon.

slpws6

That's what I thought. It just started doing this and tune has been there for a while.

DooDooBear1999

Very strange indeed.

BigGun

Why not pull the codes and see whats there. Here's how using the dic in the car. http://www.stengel.net/diccodes.htm

slpws6

Will I have a code for it if there is no cel?
Is there a way to reset all codes?

Bill Curlee

Follow this procedure. (SEE BELOW) Read your DTCs.. CLEAR then ALL and take it for a drive. Do what you normaly do to cause the issue. After it happens, immeitely with out turning OFF the ignition, READ and copy down the displayed DTCs.

If there are not any, thats important info also.

What engine performance MODIFICATIONS do you have??

Please list them:



READING YOUR Engine Diagnostic Codes



The Diagnostic Display Mode is entered with the following procedure:

1) Turn on the ignition but don't start the engine. NOTE! You can read the DTCs with the engine running and or driving down the road but it can distract you. BE careful! Some DTCs clear themselves when you turn the ignition OFF!

2) Press the RESET button to turn off any warning messages. (i.e. door open, trunk open ect)
3) Press and hold OPTIONS
4) While holding OPTIONS, press FUEL four times within a 10-second period.


Initially, on-board diagnostics go into an Automatic Mode which shows diagnostic codes in a pre-set sequence: PCM - TCS - RTD - BCM - IPC - RADIO - HVAC - LDCM - RDCM - SCM - RFA. All codes will be displayed for each. ( i.e. PCM = 4 codes) If none are present in a given module, you will see No More Codes on the display.
There are two kinds of diagnostic codes, Current and History designated with a letter suffix, “C” or “H”. A current C code indicates a malfunction is present and active in the module displaying data. A history code indicates a problem existed sometime in the last 40 or 50 ignition cycles. When not accompanied by a current code of the same number, it's potential evidence of a previous problem, now resolved, that was not removed by clearing the codes.
More likely it's an indication of an intermittent malfunction.
Intermittent codes are the most challenging of the diagnostics. An intermittent code may have happened once, may have happened more than once but is inconsistent or may be happening on a regular basis but not at the time the codes are displayed. History codes can also be caused by a current malfunction in a system that is not operating at the time codes are displayed. An example is the rear window defogger which doesn't operate until the Body Control Module detects engine rpm. For history codes set by a module that does not operate with the key on and engine off, a special diagnostic tool called a Scan Tester is necessary to properly diagnose the malfunction.
Once the system has displayed all modules, it goes into the manual mode which allows selection of each module using combinations of Driver Information Center buttons. Manual mode can also be entered during the automatic sequence by pressing any button except English/Metric (E/M). Once the display shows Manual Diagnostics, select a module by pressing the OPTIONS button to go forward or the TRIP button to go back. Once a module is selected, a code is displayed, and if more than one are present; press GAGES to go forward or FUEL to go back.
To exit the diagnostic mode at any time, press E/M. If you want to erase codes in a given module, press and hold the RESET button To reset the codes once in manual mode, press and hold RESET until it displays NO CODES Press OPTIONS to go to the next module. Repeat the steps until you have reset the codes in all the computer modules.
NOTE!! Only reset the codes IF you want to - it is NOT necessary to do this. Clearing a code does not repair a problem. You are simply erasing the evidence of it in the module's memory. If you clear the code/s, and extinguish the Check Engine Light, your emissions status ready will NOT allow you to pass an emissions test until you have completed the required driving cycles.
Once you have the codes, the next question is: What to do with the information?
First, consult the factory service manual. Any serious C5 Do-It-Yourself owner should invest in the Corvette Service Manual of the appropriate model year. The Service Manual is really a requirement if you want to understand and work on your C5. You can GOOGLE the DTC and also find information on it.




Here is very good site that explains the DTCs:


http://www.corvette-web-central.com/C5DTCcode.html


http://www.obd-codes.com/trouble_cod...d-ii-codes.php



Make sure to include the H or C suffix!!

printmanjackson

Sounds like it could have a vaccum leak

slpws6

No codes on system. Wouldnt a vacuum leak get worse as rpms go up?

printmanjackson

does it idle?

slpws6

Seems to idle normal it is CAMMED so a little hard to tell

DooDooBear1999

Going to be a stupid question, but is the cam grind made for 2500 and higher RPM range.

slpws6

Yea this problem stared happening long after the cam. I almost get Like a MISSFIRE/backfire type feeling while this problem is happening. And like I said its worst under a load if I nail the gas wot at real low rpm it's just like there is a hold on the engine until 2500k

Bill Curlee

If it were me,, I would DATA LOG the PCM and see what the following graphs are doing under load:

MAP: (Manifold Absolute Pressure) sensor value

MAF; ( MASS Air Flow ) sensor

TPS: (Throttle Position Sensor)



All those things are criticle under load especially the MAP value. Are they changing values properly?

Is your fuel pressure and fuel flow volume keeping up with demand?

I have see too many cars lately that have fuel pump electrical issues. Check the voltage on the FUEL PUMP fuse to ground and MAKE SURE that it is reading FULL BATTERY VOLTAGE. If it is less that what actual battery voltage is, it could be an issue.

The fuel pump power comes from/thru the IGNITION SWITCH and if the ignition switch contacts are burnt or carboned, it could be limiting current to your fuel pump.

The ignition can also cause other issues if it is not electrically sound.

Just some things to check.. BRAINSTORMING!

BC

slpws6

Thanks for all the help guys

Kreeess

did you ever figure it out? i have similar symptoms as you. i currently have a street tune right now on my car, waiting to tune it properly on a dyno hopefully by end of Oct. but i wanted to see if you got the issue resolved

woodman300

when I drive the car with the traction control on, it does this xxx exact thing when the tires begin to break loose. so maybe the sensors that tell the computer to retard the acceleration are bad and when you are below 2500 the car thinks the tires are breaking loose.

Kreeess

theres sensors for this? how do we change it or fix this problem? could it be just a non responsive PCM?