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jerk/surge in overdrive


KrazyCutlass1995

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i recently purchased a 94 grand prix with the 3100 motor and it has 145k miles on it with the 3100 motor in it .... well it all drives well untill i get up to about 50 mph and it goes into overdrive then i start to notice a little surge all the way up to about 70 mph then the service engine soon light comes on and stays on untill i switch off the car ... and it dont come back on untill i get back into overdrive again .... my friend has a boniville and he says its my cam position sensor? sense this is the same problem he has with his car except it has the 3800 and it was his cam sensor... is this possilble, if not what else can it be?? Thanks alot guys!!

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My wifes 3100 95 cutlass last year had a similar issue. @ 70 mph it felt like we were being bumped from behind. As it turned out it was just jumping in and out of overdrive and, it just needed a tune up. The transmission is electronic , and I don't know if this sounds like bs or not, but the best explaination I could think of (as to why this was happening), was that the whole engine is full of sensors, so if the engine wasn't producing the right voltage at a particular speed, that might freak the pcm out, and it might jump in and out of whatever gear your in cause it's trying to compensate?. Once I gave it a tune up, and cleaned off all the terminals on the coil packs, it was performing correctly again. That obviously would not happen if the tranny was vacume controlled cause the ecm doesn't do anything to the tranny.Like I said, it soulds like a stretch, but it was the only was I could rationalize what was happening.

 

good luck.

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My wifes 3100 95 cutlass last year had a similar issue. @ 70 mph it felt like we were being bumped from behind. As it turned out it was just jumping in and out of overdrive and, it just needed a tune up. The transmission is electronic , and I don't know if this sounds like bs or not, but the best explaination I could think of (as to why this was happening), was that the whole engine is full of sensors, so if the engine wasn't producing the right voltage at a particular speed, that might freak the pcm out, and it might jump in and out of whatever gear your in cause it's trying to compensate?. Once I gave it a tune up, and cleaned off all the terminals on the coil packs, it was performing correctly again. That obviously would not happen if the tranny was vacume controlled cause the ecm doesn't do anything to the tranny.Like I said, it soulds like a stretch, but it was the only was I could rationalize what was happening.

 

good luck.

 

Sounds like a problem I had as well. I had just bought the car and when I would go up small hills at a crusing speed (45-55), so I had the tranny flushed 'n filled, and then I replaced a few filters and I think my O2 sensor (I guess it really don't have much to do with this...) but after that, it was fixed. But listen to Intlcutlass before taking advise from me!

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  • 2 weeks later...

well i have changed the EGR valve since thats what a mechanic scanned it and said it was ... ses light still comes on ... and still jerks , i have tried by changeing a motor mount that was broke , cam sensor , plugs , throttle position and IAC sensor ... and still get the same jerking crap... but only when it gets into last gear and when it adjusts to the gas you are givin it when the rpm falls down low ... maybe the manifold needs to be cleaned or something?? im confused ... also is there any wires which could go to the tranny like 1 wire for each gear that i may be able to check out ... hopefully we can figure this out.... THANKS GUYS!

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My mother's 94 GP jerked in overdrive on hills too, I believe it actually ended up being the plug wires. I knew they were a problem because how the car ran when it was wet, but it solved this too.

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o , so u think it may be the wires? i havent changed them ... i only changed the plugs ... i think i will change them and see what happens.. it really is starting to annoy me ... but if it was the wires wouldent do it when i floor it??? runs good then :lol:

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