Car shake with light throttle 99gtp

[Cbierniat]

My car seems to shudder when i give it light constant gas and sometimes when i let off the gas it kinda slows down and itsreally noticeable almost as if i have a manual...If its a sign ofthe trans going i want to dump it then please help

Any feedback appreicated


99gtp 139k miles recently tuned up plugs wires timing chain oil pump


Thanks

[BNaylor]

Does it occur at any specific rpm range? You may be getting chuggle or fishbite which is the torque convertor clutch (TCC) locking/unlocking. If it feels like a bad bog then the TCC may be stuck on.

You should get it scanned for any tranny DTC error codes using a trans capable scanner. Some do not trigger the SES light but are stored.

In the meantime check the condition of the ATF fluid and level. When was the last time the tranny was serviced? ATF and screen filter?

Finally, try this. Disconnect the battery negative cable overnight and then see what it does the next day.

Note: Before disconnecting battery make sure you have your security codes if Theftlock is active.

[Cbierniat]

I've never had my trans serviced... how much does it cost...and its the lower RPMs ...and seems like when i give i t a lot of gas it reacts slow and kinda like it misses grabbin like i get all rpms and it doesnt really move

[BNaylor]

With 139K miles the basic tranny service is your best bet as a starting point. Pan drop only replacing ATF (Dextron-III) and screen filter. At shops the cost varies depending on where you live in the US and the type shop. You have the GM dealer, tranny shops, national service chain stores, and the lube places. Probably from around $60 and up including the ATF and filter. I would not get a full power flush or fluid exchange at that mileage but the shops may try to convince you to go that route.

[GPFred]

I had a similar issue with either the chuggle or the engine bogging down on heavy acceleration. After having done a tune-up, had the converter replaced, and replaced 2 of the coil packs, it was finally determined to be the fuel injectors. I changed the seals and had the injectors cleaned, but they were just worn out. Put some remans in and the car sits up and screams now. Almost have too much power. I would see about getting the injectors cleaned, cost me $100 to have it done, but they were too worn out.

[BNaylor]

Originally Posted by GPFred

I had a similar issue with either the chuggle or the engine bogging down on heavy acceleration. After having done a tune-up, had the converter replaced, and replaced 2 of the coil packs, it was finally determined to be the fuel injectors. I changed the seals and had the injectors cleaned, but they were just worn out. Put some remans in and the car sits up and screams now. Almost have too much power. I would see about getting the injectors cleaned, cost me $100 to have it done, but they were too worn out.

What engine was this?

[GPFred]

3.1 2000 GP with about 99K now.

[BNaylor]

Originally Posted by GPFred

3.1 2000 GP with about 99K now.

Glad your got your problem resolved. Based on his symptoms cleaning or replacing the fuel injectors in a L67 SII 3800 probably won't help although it is not a bad idea especially with the mileage he has.

When one or more of the 33 lb. fuel injectors acts up in a L67 he'll get more than light throttle chuggle/fishbite especially when full boost kicks in. Also, random/fixed misfire DTCs due to the crank sensor sensing variation.

Personally, I'd start with the tranny on this one.