[airjamer]

Hello,
I just bought my first corvette last week. It is a 97 auto with 60k miles. Let me first start by saying I am no expert in this area and as far as I can tell the car is clean and the only mods are Corsa exaust and aftermarket air filter. Here is the problem I am having...

-Once the car gets do normal temp. I notice a slight jolt (hesitation or stutter) at low rpm. in fact the only time it does it is when i just barely hold down the gas. (either when letting off or just starting to accelerate.) Also sometimes while cruising at 40-60 with my foot off the gas the tac starts hopping from about 500rpm to 1000rpm back and forth. there is no check engine light or any error codes. I took it to the dealer and they plugged it in, found no errors and said there was nothing they could do. The problem is usually subtle, but i dont want it to turn into something worse. heres a couple other things I noticed that might be related in some way (or they could just be a bunch of other problems)

-The noise from the fuel pump behind the driver seat gets louder and softer when using other electrical components like windows, blinker etc.

-I had the service abs/traction control error which went away after i turned off the car.

-also i noticed it doesnt do this when parked only while driving.

The dealer put new plugs and wires in and as far as i know that is all they did to it. here is what my little brain can come up with...

1. Its electrical...the noise in the fuel pump being disturbed by other electrical accessories sounds like a bad ground which could be causing a misfire right?

2. If it were a misfire wouldnt i get an error code or something? plus wouldnt I get the same problem with the car in park? Maybe a transmission problem?

3. Maybe its normal...afterall this is my first vette.

Anyways, are there an easy solutions for me to rule out some things or any known issues like this on these cars? any help would be greatly appreciated. thanks

 

[BlkNBlkC5]

I have a very similar issue with my 2002 except it's only at idle, when I hook it up to the diagnostics the misfire (s) go away when held at any rpm above idle. It also surges from 500-1000 but only when I let the car idle in Drive and this is only on occasion. While cruising between 40-60 and I let off the throttle it will stutter but not surge. I as well do not have any current codes and my shop can not figure out why my car does this... :huh:

 

[extanker]

this is when GOOD testing equiptment is a must.the tach jumping i feel is a clue.do a basic check eg grounds,vac. hoses,elect conn. etc. i would monitor crank shaft position sensor and cam shaft position sensor with a lab scope.when it starts to run strangly it can be found with the right test gear

 

[Patrick]

Just saying, the catalytic converters on our 2002 C5 Z06 were clogged at just 25,000 miles on the odometer.

The amount of performance issues it caused are too many to list, but hesitation, idle issues, bad gas mileage are just a start.

And... just like you ... no codes!

Cars need to inhale, and exhale.:thumbsup:

 

[BlkNBlkC5]

Just saying, the catalytic converters on our 2002 C5 Z06 were clogged at just 25,000 miles on the odometer.

The amount of performance issues it caused are too many to list, but hesitation, idle issues, bad gas mileage are just a start.

And... just like you ... no codes!

Cars need to inhale, and exhale.:thumbsup:

That's what I thought it was but I just replaced my midpipe and the new one was for a Z06. I also replaced all four O2 sensors with Denso, better performance, but still the rough idle. I even reset my PCM with the procedure I found on this site with still no luck. I cleaned the MAF sensor, added octance booster to this crap California gas, put taylor 8mm wires with NGK plugs and still nothing... Do you have any other suggestions?

 

[49865]

First - Your Taylor 8mm wires could (possibly) be an issue. I would NEVER run anything on a corvette accept for GM wires. They are specifically designed for your car, the Taylor's are not.

Second - I would rule out the fuel pump noise issue. I have had that exact same noise in the fuel pump, also pulses with blinkers etc. My car runs perfectly and has done that now for about 35K miles. I'm not saying that it is normal for our cars to do that, but it is definitely not related to your all your problems.

I would try to throw on a set of GM wires just to see if it fixes your problem. I have heard many people having issues with after market wires, even the $800 MSD wire and coil set I have heard is no good....... someone might know for sure!....

 

[airjamer]

Thanks Everyone,
I will check the plugs, wires, grounds, and air filter this weekend to rule out any easy fixes. Anything else that could be an easy fix. Any way to test sensors even though there are no error codes? I only ask because a friend at work who drove in it with me said it sounds like a sensor going bad. Also if there is no check engine light is it safe to drive?

 

[extanker]

many sensors can be tested

 

[inaband]

You can drive it, also the fuel pumps on 97's are loud by nature, nothing wrong w/ them....

 

[JBsZ06]

My votes on the spark plug wires too..

Go back to the GM wires and make sure you get that double click on each and every coil as you install the wire...

JMO and good luck..

Keep us updated..

 

[airjamer]

Just found the problem...
I took off the air filter looking for animal nests and such clogging the intake and what I found was a mass air flow sensor butchered to hell. The screen was taken out and the wall that splits it in the middle was grinded with a rotory tool. I guess whoever had this car before me thought it would give him a little boost. Anyways I replaced it and the car runs 10 times better and with about twice the mpg. I told the dealer and they are going to reinburse me the money. Thanks everyone for your help.

 

[JBsZ06]

congratulations and thanks for posting back up what you found.

Enjoy that car and this site.


JB