Every once in a while my car would stutter under acceleration, like once every couple months, i thought no biggie it was my fault on the clutch. Well its been pouring rain in so cal and on my way home from work i noticed that from a stop, as i released the clutch (engine idle is fine, about 650rpm) slowly/easily/quickly the car would hesitate a little bit. Once i was on the high way i noticed that i was having terrible stutter/hesitation under acceleration in almost any gear when i put my foot down on the gas (not pedal to the floor hard acceleration) just a light speed up amount of foot pressure, it would stutter and hesitate badly. At first it seemed like my tires were just spinning trying to grab traction, i soon realized that was not the case. No check engine lights at all. haven't seen any ever.

I have been searching the forums like a mad man for the last hour, but all the treads seem to be about auto vettes having stutter due to the torque converter.

My car.
122,000 miles
1992 lt1
6spd stick
Opti re placed along with water pump last year by dealer
new oem spark plugs about 6 months ago
New fuel injectors from FIC about 9 months ago
replaced fuel filter about 9 months ago

I really appreciate your guys input, i need to be a work the next couple of days.

So Cal weather the last couple of days, cold and pouring rain. she did sit outside in the rain the last couple of nights.

FORGOT THIS
while taking off from a stop their is a LARGE STUTTER, mechanical noise, seems like i burped the clutch or something. Like i depressed the clutch let off really quick, then depressed it and let off again. This all happens while i slowly let off the clutch as normal.

WHAT THE FRIG IS HAPPENING?

 

Off the top of my head here are some suspects:

Check for spark-leak in the dark.
IAC
TPS
fuel pump inlet sock
intermittent ground strap connection
battery improperly secured and or touching the frame as in Optima top post terminal
global conspiracy

 

Refresh my mind please what is the TPS?

 

Throttle position sensor

 

Just so you know even though all those parts have been replaced doesn't mean that any of those replaced parts are not the problem.It could be install error(tightened distributor cap too tight & cracked cap,seal for cap has tear-not lined up properly),or defective part(s).This all can happen.Have you gone through any large puddles?Do you have garage?If you do,allow car to run inside with garage door open & if you have dehumidifier,bring that inside garage & turn it on after car has been ran inside garage for about 10 minutes.Leave dehumidifer on all night & empty it before it becomes full-you may have to keep an eye on water level & make sure garage is sealed up the best you can.Doing this will dry everything out & may cure the issue you are having short of pulling off cap & drying inside of distributor.I'm not saying this will fix your problem but to me it sounds like a ignition issue since your complaint happened when driving in rain.Also have hood open while dehumidifier is on & remove air filter because it may be somewhat wet & will be dried with above process.Post results

 

Could be almost anything.....that said, did it throw a code. Similar symptoms to mine when I killed a fuel pump. (stutter & hesitation under acceleration).

Fuel pump
Fuel filter
Other gas related problem?

 

I have the next three days off, so forgive me for not diving into eleminate any of the above possibilities, right now im getting an idea of all the possible causes. Over the next couple days i will go thru each one of these areas to eleminate them as a possibility. I appreciate you all giving me a list of possibilities from your experience.

Having said that,
I have not seen any check engine lights, i will see if i can pull some codes on the dash tonight and look them up in my service manuals.

Does this sound like a possible clutch issue? Maybe its slipping, badly? I bought the car at 100,000 miles and taged on 20,000 over the last two years. Could be the stock clutch needing replacement? (I have kinda been expecting to replace the clutch since i bought the car.

 

Could be bad plug wires. Were they replaced. As said by another member, because things were replaced doesn't necessarily mean everything was done correctly. I would start with replacing plugs and wires.

 

Normally a slipping clutch in it's first stages of failure is more noticeable in higher gears (4-5-6)--if you can accelerate hard at 50 mph in fifth gear w/out a sudden rpm rise/flare as you accelerate--then the clutch is likely ok-- or at least not causing your present problem. Some other members had some good ideas on where to start checking.

 

if you are on a level surface and put it in a fourth and pull forward. then the clutch has good life left in it. you may have a cat starting to plug up. that would mean fuel in going through the exhaust from a misfire. egr malfunction. battery could be getting weak and so on.

 

Something folks haven't mentioned is the ICM and coil.

I've had 3 ICMs go bad in the last couple years, still need to get a replacement for the third one. It does not like the heat and will cough sputter and fight until enough air flows over it to cool it down.

 

Another thing to add to possible causes is lazy O2 sensors. This would show up under closed loop operation with light acceleration.

They can cause a miss by not responding quickly enough for the computer to add fuel resulting in a lean condition. Accelerating hard (going to open loop operation) will result in the miss going away.

I had this happen to me on another car. and it (a miss) is curerntly something we are tracking down on the wife's 94 Vette. We will be replacing the O2 sensors shortly.

On her car we are currently trying to resolve 3 issues: a miss, taking longer to start, and intermittent ASR/ABS trouble lights on the dash.

Never a dull moment.

 

So this is where i am at, i have pulled any stored codes and i came up with.

Module 1 (CCM)
Code H25
Code H72
Code H74

When i looked these up in my shop manual it looks like 25 is IAT, but i don't see codes 72 or 74.

When i checked here http://www.corvettebuyers.com/c4vettes/ecm.htm i found that code H72 is Gear Selector Switch Fault (Start Lockout). What is this?

Still no code 74 definition

 

I got a Code 72 and 74 as well. Not sure what either means. The gear lockout I think is the computer noticing that the CAGS has been removed and it throws up a code because of it. At least, that's my theory. Hopefully someone can corroborate it?

 

The code you looked up is the ECM/PCM(engine) code not the Central Control Module(CCM).Codes stored 25,72,74 in the CCM are-(25) courtesy lamp relay coil circuit open or shorted to ground,(72) LCD dimming output circuit open or shorted to ground,(74) LED display dimming output circuit open or shorted to ground.These codes are for the CCM.There is no code 74 for ECM/PCM(engine) so I'm assuming these codes were from just the CCM.You are correct in that code 25 & 72 from ECM/PCM(engine) are related to IAT & gear selector switch.You need to see if there is any ECM/PCM(engine) codes.Post engine codes if any

 

does this car have any issues at wide open throttle?