Help my 98 coupe was sitting in the garage for a few weeks when I went to start it up I am getting a Reduced Engine Power Msg and Service Traction Control MSG. The car runs very rough, when trying to give it more gas it will not go above 2K RPM's no matter how far you push on the gas?

Anybody have any ideas? Prior to parking there were no messages.

Thanks :mad

 

I had a similar problem whith my -99. Car had run 800 miles and when I came to start it one morning - reduced engine power!
Turned out it was the PCM that had gone bad. Once problem identified, got a new one installed in no time, and on my way! All under warranty!
:) :) :)
Mikael

 

another possibility is that the PCM is receiving an extremely rich or lean condition from the O2's. i actually created the very same symptoms you are experiencing by going too far on my MAF T WOT adjustment. i effectively set my enrichment so rich that the O2's were registering 990mv!!! The PCM will go to reduced power when it 'anticipates' certain values but gets others (feedforward). have you tried starting the car up several times?


[Modified by rwj383, 7:21 AM 2/11/2002]

 

My guess would be that it's (low) battery voltage related as it's been sitting a while. You're describing how things look when the VATS has been triggered. It's very unlikely that the PCM is dead as this is perfectly normal behavior. I'd try some simple things first like cleaning any corrosion at the battery terminals and reseating the connectors at the BCM (under the cover in the passenger footwell.) If that doesn't work you might take a look at a procedure I posted here:

http://forums.corvetteforum.com/zerothread?id=233744

and try that. I wouldn't recommend that if your battery seems low since it requires leaving the key on for about 45 minutes or so. If you can check your codes on the DIC and find a P1631 that will confirm the VATS thing. I don't remember if you need a scan tool to see this code or not. If you can scan, you would be able to see any O2 codes that might have been set.



[Modified by ToplessTexan, 8:40 AM 2/11/2002]

 

I had the same 2 messages displayed but my problem turned out to fixed by replacing the two components in the "drive by wire" system. I hope that you don't have the same problem because it ain't cheap to fix. Good luck! :cheers:

 

Here is the TSB for the fix on the 98 :yesnod:

REDUCED ENG. POW. MESSAGE ALONG W/ PARTIC. PWRTRAIN #87-65-16
SUBJECT: REDUCED ENGINE POWER MESSAGE ALONG WITH PARTICULAR POWERTRAIN TROUBLE CODES (INSTALL NEW TAC-MODULE IF STRATEGY IN SERVICE MANUAL FAILS)

MODELS: 1997-98 CHEVROLET CORVETTE WITH 5.7L V8 ENGINE (VIN G - RPO LS1)

CONDITION #1: INTERMITTENT REDUCED ENGINE POWER EVENT, ACCOMPANIED BY P-1516, OR P1518 TROUBLE CODES.

IF A SITUATION ARISES WHERE A P-1516 TROUBLE CODE IS ACCOMPANIED BY A

P-1120 AND/OR P-1220 TROUBLE CODE, THIS SERVICE BULLETIN DOES NOT ----------------------------------------------------------------- APPLY. IN THESE CASES THE TECHNICIAN MUST USE THE NORMAL STRATEGY ------------------------------------------------------------------ BASED DIAGNOSTIC. -----------------

CONDITION #2: INTERMITTENT REDUCED ENGINE POWER ACCOMPANIED BY TROUBLE CODE P-1125 AND ANY OF THE FOLLOWING TROUBLE CODES:

P-1276 P-1281 P-1286

CAUSE:

CONDITION MAY BE DUE TO DIAGNOSTIC SOFTWARE AND CALIBRATION IN THE TAC-MODULE WERE NOT OPTIMALLY UTILIZED.

CORRECTION:

IF THE ABOVE CONDITIONS CANNOT BE CORRECTED USING THE NORMAL STRATEGY BASED DIAGNOSTICS LISTED IN THE SERVICE MANUAL, INSTALL THE NEW TAC- MODULE LISTED BELOW.

PART INFORMATION:

NEW TAC-MODULE PART # 25319443

 

Thanks everybody I will check out all of your suggestions, So far have found the air pump not functioning, and 11.5 volts when idling.
Thanks again

 

The low voltage condition will cause a number of sensors to go out of range...engine knock sensors, traction control, even low windshield washer fluid. :D Pull enough codes in the first two categories (PCM, TCS) and you will get a Reduced Engine Power fault.

To clear the code, (much faster than the "Texan" method although he has better pics of chicks hanging out on his cars), try this:

1. Engine off, ignition key on.
2. Hit reset to clear any failure messages (reduced engine power, door ajar, etc.)
3. Holding down the Configure key, hit fuel key 4 times (you'll get good at this)
4. It will start through a manual scan of current code counts. You don't have to wait...hit reset once and you will go into manual mode.
5. Use config key to scan down to first area with codes. (PCM will be the first and will probably have codes) Hold reset key for 2 seconds. All codes get cleared. Then use config key to scan to next group (TCS) and do the same. If you want to scan through the individual codes in each area, use the gauges and fuel keys to move up and down in that area. You can reset individual codes as you write them down if you want. The key above config (sorry it is early and my memory is shot) can be used to scan upward back through the group list. Clearing PCM codes should reset your check engine light and reduced engine power messages.
6. When you are done, hit the E/M key and it will clear the dic and return you back to normal. If you clear TCS codes with traction control off, it will return it to the "normal" TC on mode. Just hit your button again to go back off TC if you want that.

Another thing that will set codes is if the temperature has fallen significantly and you had a relatively empty gas tank. You will get condensation in the gas tank and a little water in the gas. That will trip the REP code...I've had that one happen.

All for now. Hope this was helpful.

Doug


[Modified by Snowman, 6:01 AM 2/12/2002]

 

Fix that voltage and you should be a happy camper again. :yesnod:

 

Well thanks to everybodys help I found battery acid leaking from the baterry, I replaced the battery and things look good.

Thanks for all the help :D

 

:cheers:

Damn Delcos :cuss

 

I don't think it's the battery as much as it is some torque-happy wrencher tightening the battery terminals too much!