TCC releasing at crusing speeds with light throttle

[joecar]

Well see how it goes.

[HellKnightHicks]

Thanks for all of your help fellas. Ive learned alot about tuning tannies and how it all works and goes together.

I looked into Circle D and I really like his converters and the brains behind the TC's If I buy one i think it will be from him..

I dunno whats going to happen with the tranny shop I ordered mine from... Lou seems like an honest guy and that he really tries hes always been nice and helpful... But I dont have a complete and working tranny at the moment.

Ill keep everybody posted.

[HellKnightHicks]

Shouldnt Table D2903 be close to 0.

The clutch engauges when the pressure is reduced correct? Or am i wrong?

[Taz]

Joecar is better versed with the fluid mechanics of auto transmissions than I am ... but here is my understanding of how the TC lockup works in a 4L60.

The TCC Solenoid Valve is "normally open" when TC lockup is NOT commanded. When the PCM initiates TC lockup it closes the TCC Solenoid Valve - which causes fluid pressure to begin to increase in the TC. The rate of fluid pressure increase is controlled by the TCC PWM Solenoid Valve - to promote a smoother (i.e. softer) engagement of TC lockup.

Regarding D2903 - I generally set this no lower than 85%. Corresponding, I generally set D2904 to 99%.

[HellKnightHicks]

I would have to reduce the pressure wouldnt it.



At least on the back side of the clutch

[joecar]

...

The TCC Solenoid Valve is "normally open" when TC lockup is NOT commanded. When the PCM initiates TC lockup it closes the TCC Solenoid Valve - which causes fluid pressure to begin to increase in the TC. The rate of fluid pressure increase is controlled by the TCC PWM Solenoid Valve - to promote a smoother (i.e. softer) engagement of TC lockup.

This is correct.

[joecar]

Shouldnt Table D2903 be close to 0.

The clutch engauges when the pressure is reduced correct? Or am i wrong?

D2903 is the minimum PWM duty cycle that can be commanded while the TCC is locked.
D2904 is the maximum PCM duty cycle that can be commanded while the TCC is locked.


Taz strategy is good, it ensures that the TCC won't slip when the PCM minimizes PWM DC:

Regarding D2903 - I generally set this no lower than 85%. Corresponding, I generally set D2904 to 99%.

this may cause the initial lock to be felt (slightly abrupt), but that avoids it "slipping" into lock and "slipping" out of lock.

[HellKnightHicks]

feels like annother gear... but i can tell you this change is not making my TCC hold lol

[joecar]

feels like annother gear... but i can tell you this change is not making my TCC hold lol

Set D2903 to 98% and D2904 to 99%.

If the TCC is slipping then also do this:
- check pump flow (remove return line form cooler and catch fluid from cooler exit), make sure you get at least 2 quarts in 20-30 seconds.
- check line pressure (at the tap on the side of the case), in D expect 60-80 psi at idle and above ~130 psi driving at light throttle, above ~170 psi at medium throttle, above ~200 psi at WOT.

[HellKnightHicks]

What gauge would you recommend?