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Need to confirm trans issues rather than sensors.

F

fastline

New member
2005, 3.8L, 135K,

Posted a while back and just need to confirm I don't have something sensor related going in with this car. Has the typical oscillation in 4th with TCC locked or unlocked, I can't really tell. Also at random, car will seem to hang in a taller gear at a stop and slam back to 1st when you take off.

I recently unplugged the battery for other repairs and was obviously shifting much harsher. I also noticed when first starting the car that it died, then started and rpms drop almost to stall, then catches itself and levels off.

NOT DTC codes have been set but I have not been able to review the live data from the Trans yet to determine TCC state, duty, etc. I just need to confirm the trans is toast before I go further. I know some have mentioned other things like an engine miss but I cannot really detect a miss and certainly runs like a top when the pedal down.
 


sounds like you have a few things happening.

http://www.tripleedgeperformance.com/TCC-rpm-oscillation.html
This generally happens when the valve body has excess wear in the TCC regulated apply valve area but also has other causes. Excessive fluid leakage in this area of the valve body causes TCC apply pressure loss and can lead to uncontrollable TCC operation which causes the engine rpm to bounce up and down a bit. This problem is noticed most after driving a while and speeds between 42 and 70mph and in 4th gear.
Click to expand...

http://www.tripleedgeperformance.com/No-Forward-Cold.html
One of the most common problems I have found after the milege gets over roughly 60K miles. The scenario.... You are driving in traffic for a while OR your car has sat for a while and is a cold startup. You put the car in Drive range and it wont move, or if driving you come up to a stop light and in heavy traffic and the light turns green and SUPRISE!!! You are holding up traffic with a car that wont go anywhere. The most common cause of this problem is a worn out inner surface of the Input clutch piston.
Click to expand...

When you disconnect the battery the PCM loses its adaptive shift knowledge and will shift harshly until it "learns" from your driving habits.

The startup issue could be a dirty IAC pintle, dirty MAF sensor, or vacuum leak.
 
No codes have ever came up on diagnostic scan. I did also try tapping the brake durring the OD oscillation to unlock the TC and it does not do a thing. That puzzles me at the moment.
 
UPDATE!!!
I really need to be driving this car, not the other half! Finally drove it today to realize it IS NOT doing to TCC oscillation AT ALL! I was very happy about that, which may help in getting closer to the find. HOWEVER, I did note that after some driving, the trans will start shifting too firm in all gears. This happened after I stopped, used reverse, then put car in 1st for a distance, then back to drive. After that it was shifting hard.

Mamma also indicates at stops, sometimes at take off there is a hard bang. I have experienced this and believe the trans is holding in a taller gear and waits until throttle to downshift to first for some reason. I suspect all the hard shifting and failure to downshift as a high line pressure? But why?

One of the biggest developments is when I fired it up today, I could detect a slight miss so I am going to throw plugs/wires at it. Still seems to run out fine in higher RPMs but I can detect something slight. It is no quiet, I can't hear what it is really doing.

However, there is more to this story. Unplug battery and TCC oscillation goes away?
 
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