Engine Hesitation At Constant Speed


arcy
07-09-2006, 09:58 AM
1998 3.5 Intrigue. ~125K miles

For some time now, the car seems to jitter or hesitate when going uphill at a constant speed. Happens when in cruise control or not in cruise control. Jitter feels like it is going to shift gears, but doesn't. If going uphill and giving it gas to accelerate, there is no hesitation or engine jitter. Doesn't matter if the engine is cold or hot.

Have OBD II reader and have not codes or console lights.

Has anyone else expierience this problem?? Maybe it is normal for this car.

Thanks.

BNaylor
07-10-2006, 09:43 AM
The problem is not normal. It sounds like you are experiencing what is known as "chuggle" or "fishbite". It is the torque convertor locking and unlocking and shows up while the car is under some sort of load.

It can be caused by an ignition related problem such as spark plugs (misfire), fuel delivery problem or worse case a problem with the 4T65E tranny such as the TCC solenoid.

arcy
07-12-2006, 06:06 AM
How would I check some of these issues out? I have a OBD II reader and do not see any codes during the times of "fishbite".

If it was misfiring, I thought it would display an error code?

As for the fuel delivery concern, would I need to take it to a shop to check the fuel line pressure? I know the fuel filter has been replaced a few times already - just regular maintenance stuff.

Also, for the transmission, I would definitely need to take it in to have an experienced professional look at it. Could they simply replace the TCC Solenoid or would the entire transmission need to be replaced or rebuilt?

Thanks for your assistance..

BNaylor
07-12-2006, 09:23 AM
How would I check some of these issues out? I have a OBD II reader and do not see any codes during the times of "fishbite".

It is a difficult problem to troubleshoot. What brand scanner are you using? It must be trans capable.

If it was misfiring, I thought it would display an error code?

Not all misfires wil set a misfire DTC error code such as P0300 random or P030X specific cylinder. Also, the SES light should blink once a misfire is detected. One of the corrective/troubleshooting steps for this problem is to replace the spark plugs and ignition wires/modules depending on your mileage. GM has a TSB out recommending replacement of the throttle position sensor (TPS) but I've never seen that actually fix the issue.

As for the fuel delivery concern, would I need to take it to a shop to check the fuel line pressure? I know the fuel filter has been replaced a few times already - just regular maintenance stuff.

If you can DIY, you can get a fuel pressure tester and hook it up yourself. Not that expensive.

Also, for the transmission, I would definitely need to take it in to have an experienced professional look at it. Could they simply replace the TCC Solenoid or would the entire transmission need to be replaced or rebuilt?

Thanks for your assistance..

I would have the tranny shop use their scanner to see if any tranny error codes are stored, especially any slippage or PCS codes. Some do not trigger the SES light but will store for retrieval. The shop will probably try to talk you into getting a complete rebuild but valve body problems like solenoid replacement can be done by itself with a rebuild. But I would make sure it is not an engine related problem first.

You're welcome and good luck!

99Intrigue3.5
07-16-2006, 07:07 PM
My 99 3.5 was doing something similar. Very occasional, long time between. Eventually a P0300 code was set (not helpful). Search for that code, you'll see the thread.

It seems to have been fixed by replacing the MAF (easy to test, disconnect the MAF harness for a while).

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