random stumble and miss
Thread Starter
Registered User
Joined: Dec 2003
Posts: 54
random stumble and miss
Hello,
im hoping you can help me out. i have a stock '94 3.4, slushbox (non cali) camaro. ive tried searching and did not find much that was relevant (that i knew of).
i have a miss (idle and while revving, but it is harder to notice). at idle, the miss is about every 3-4 seconds (plug wires are good, new plugs within ~3K miles).
i also have an intermittant problem: at 2200 RPM while accelerating at 1/2 to 3/4 throttle, the car will studder pretty bad. it will drop to 2000 RPM, then i accelerate back up to 2200, then drops back to 2K. it repeats. if i give it more or less pedal, i can get by this. if i go WOT, it runs pretty good but i still feel a miss. TPS replaced, to no avail.
today, while sitting in traffic, it started to miss pretty bad. felt like it was idling on 4 or 5 cylinders. i went to get through the intersection and it still felt like it was running on about 4 or 5 cylinders again. water temp was at 180, BTW.
i parked it for 15 minutes at the store and it ran like a top on the way home.
it is my G/F's car, so i dont get to see how it is doin often. she said it stumbles while accelerating once or twice a day (as if she let off the gas pedal and then hit it again). she said it does it warm or cold. she has not had the problems i have had.
also, the car will shut off every great once in awhile. always after idling for a bit (water temps are 180 or less, but i do live a 1/4 mile from the sun. tucson). i dont think there is any relation to the above problems, but i toss that out in case.
from what i have read, the 94 requires a scanner (as opposed to a 30 dollar code puller) to get codes. the CEL/SES light has not come on ever, but i entertained the idea to see if something was stored in KAM that did not toss a light.
i dont have the cash for a scanner (unless someone has some good prices known to them - i read Injuneer's semi-sticky about the code situation on the 94's. i dont think i can afford stuff at prices listed.
im thinkin it is an ignition related problem (i had previously tested FP for fun, and it was within spec). the jumpy tach sounds ignition-ish to me, and the fact that it is semi heat related (got a lot worse when it was hotter).
the ignition stuff is pretty pricey, and since i cant get codes, im hoping someone might have an idea of what to test replace. the seeming short bursts of problems makes it tough for me to try to bench test components - unless they are acting up at that moment, they will test fine.
what order would you think the culprit is? im thinking ignition module might be no 1 on the list. but i am old school and dont know much about CDI ignitions. do crank sensors fail often? what are symptoms of those failing? ditto for coil pack and ignition module.....
i would really welcome and appreciate any and all help and thoughts.
thanks so much, and sorry to be so long winded - i tried to give enough detailed info to eliminate possible questions.
many thanks!!!!!!!
im hoping you can help me out. i have a stock '94 3.4, slushbox (non cali) camaro. ive tried searching and did not find much that was relevant (that i knew of).
i have a miss (idle and while revving, but it is harder to notice). at idle, the miss is about every 3-4 seconds (plug wires are good, new plugs within ~3K miles).
i also have an intermittant problem: at 2200 RPM while accelerating at 1/2 to 3/4 throttle, the car will studder pretty bad. it will drop to 2000 RPM, then i accelerate back up to 2200, then drops back to 2K. it repeats. if i give it more or less pedal, i can get by this. if i go WOT, it runs pretty good but i still feel a miss. TPS replaced, to no avail.
today, while sitting in traffic, it started to miss pretty bad. felt like it was idling on 4 or 5 cylinders. i went to get through the intersection and it still felt like it was running on about 4 or 5 cylinders again. water temp was at 180, BTW.
i parked it for 15 minutes at the store and it ran like a top on the way home.
it is my G/F's car, so i dont get to see how it is doin often. she said it stumbles while accelerating once or twice a day (as if she let off the gas pedal and then hit it again). she said it does it warm or cold. she has not had the problems i have had.
also, the car will shut off every great once in awhile. always after idling for a bit (water temps are 180 or less, but i do live a 1/4 mile from the sun. tucson). i dont think there is any relation to the above problems, but i toss that out in case.
from what i have read, the 94 requires a scanner (as opposed to a 30 dollar code puller) to get codes. the CEL/SES light has not come on ever, but i entertained the idea to see if something was stored in KAM that did not toss a light.
i dont have the cash for a scanner (unless someone has some good prices known to them - i read Injuneer's semi-sticky about the code situation on the 94's. i dont think i can afford stuff at prices listed.
im thinkin it is an ignition related problem (i had previously tested FP for fun, and it was within spec). the jumpy tach sounds ignition-ish to me, and the fact that it is semi heat related (got a lot worse when it was hotter).
the ignition stuff is pretty pricey, and since i cant get codes, im hoping someone might have an idea of what to test replace. the seeming short bursts of problems makes it tough for me to try to bench test components - unless they are acting up at that moment, they will test fine.
what order would you think the culprit is? im thinking ignition module might be no 1 on the list. but i am old school and dont know much about CDI ignitions. do crank sensors fail often? what are symptoms of those failing? ditto for coil pack and ignition module.....
i would really welcome and appreciate any and all help and thoughts.
thanks so much, and sorry to be so long winded - i tried to give enough detailed info to eliminate possible questions.
many thanks!!!!!!!
Thread Starter
Registered User
Joined: Dec 2003
Posts: 54
I never pinpointed a cause. Swapping wires *might* have helped it a bit, though I never found a source of leakage with the old ones (nighttime light show, etc). And eventually the issue seemed to mostly clear-up I guess (it's not my car so I don't get to keep real close tabs on day-to-day 'feel').
In my experience with issues like this (generically speaking), the ignition is likely, and the plug wires are kinda put in harm's way on these 3.4's.
Also, if you have a '94+, you can see some pretty decent PID's if you have access to a scanner. That might be revealing. If your EGR, for instance, has a piece of carbon holding one of the ports open (on the digital EGR, there are 3 ports in there IIRC), that can cause a low, goofy idle.
All in all, I did swap the wires (seemed to help), the TPS, and one coil. The swapping was done at different times and the wires seemed to have helped more than anything.
Let me know if there's other info that might help.
Good luck.
In my experience with issues like this (generically speaking), the ignition is likely, and the plug wires are kinda put in harm's way on these 3.4's.
Also, if you have a '94+, you can see some pretty decent PID's if you have access to a scanner. That might be revealing. If your EGR, for instance, has a piece of carbon holding one of the ports open (on the digital EGR, there are 3 ports in there IIRC), that can cause a low, goofy idle.
All in all, I did swap the wires (seemed to help), the TPS, and one coil. The swapping was done at different times and the wires seemed to have helped more than anything.
Let me know if there's other info that might help.
Good luck.
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