Stumbling with acceleration
Thread Starter
Intermediate
Joined: Jun 2000
Posts: 34
Likes: 0
From: Suffern NY
Stumbling with acceleration
Just recently I posted on this topic but got little feedback, so I'll try again. Last week, I noticed that only under load (for example, uphill hard acceleration with the A/C on) my 99 C5 will "stumble" and almost seem to misfire. I changed the plugs and cleaned the air filter with no success. New gas also doesn't fix the problem.
Any ideas ?
Fuel filter ? MAF sensor ? IAT sensor ? :confused:
Help.
Roy.
Any ideas ?
Fuel filter ? MAF sensor ? IAT sensor ? :confused:
Help.
Roy.
Melting Slicks
Joined: Aug 2000
Posts: 2,248
Likes: 1
From: Newland US
Re: Stumbling with acceleration (royeus)
royeus,
Did you pull up any codes? The ignition system is under the most stress during heavy acceleration, but a lean fuel condition could also cause the stumble.
Did you do the plug change and the filter cleaning at the same time? For example, you may have replaced a bad plug, but perhaps introduced an air leak during the filter cleaning process. Probably an unlikely scenario, but who knows.
I would look carefully, to make sure that there is no unmetered air entering the throttle body; if no problem there, then you might use your ohmmeter and get some resistance readings on the ignition wires.
If the wires check OK, then I guess that fuel pressure and check of the coils would logically be the next step.
Good luck; let us know how it goes.
Mark
[Modified by MDT, 12:13 PM 7/23/2002]
Did you pull up any codes? The ignition system is under the most stress during heavy acceleration, but a lean fuel condition could also cause the stumble.
Did you do the plug change and the filter cleaning at the same time? For example, you may have replaced a bad plug, but perhaps introduced an air leak during the filter cleaning process. Probably an unlikely scenario, but who knows.
I would look carefully, to make sure that there is no unmetered air entering the throttle body; if no problem there, then you might use your ohmmeter and get some resistance readings on the ignition wires.
If the wires check OK, then I guess that fuel pressure and check of the coils would logically be the next step.
Good luck; let us know how it goes.
Mark
[Modified by MDT, 12:13 PM 7/23/2002]
Le Mans Master
Joined: Oct 1999
Posts: 8,205
Likes: 40
From: Tucson AZ
Re: Stumbling with acceleration (royeus)
Have you checked with a dealer about this? :bb There were problems like this found during development and it was a software glitch. They should be able to program you to a better response. Good luck. :yesnod:
Melting Slicks
Joined: Jan 2001
Posts: 2,635
Likes: 2
From: Aloha, Oregon
Re: Stumbling with acceleration (carpe dm)
well, you are feeling the same thing i am. If you could get ahold of ScanEase, run the Tech2Misfire parameter table. that will definitely tell you something. this is how i started my diagnosis that lead to finding a bent exhaust valve on #7. If you dont have Atap or scanease, then you can go buy a basic compression test kit for $20 and check all cylinders. just a piece of mind if nothing else. be sure to pull all the fuel pump and ignition fuses before turning the motor over with the plugs and wires off. also, reading your plugs can point you in a direction. if one cylinder is not firing consistently, it will be dark, maybe even wet. a normal plug should have a greyish/brown tint on the ground strap and center electrode ceramic under normal conditions. I am saying all this assuming you have checked all the basic things like loose plug wire connections.
Thread Starter
Intermediate
Joined: Jun 2000
Posts: 34
Likes: 0
From: Suffern NY
Re: Stumbling with acceleration (MDT)
No codes (unfortunately). My suspicion is unmetered air. And I wish I had a scan tool. I will really hate ( :mad ) having to take this in to Paramus Chevy. They're the worst, but only "Corvette dedicated" dealer in my area.
Roy.
Roy.
