I have the 4T65E in my 1994 Z24 remember? Been a while. Got things tuned pretty good. My problem, still, it the TCC apply rate is still too fast for my application. My line pressure provides a bump shift that is on the soft side of firm. When my TCC locks it's sudden and abrupt. I have the slowest setting of 10% for rate of lock. Is there something else that I can change, or can you send me a better calibration? I feel that this current setting should be more like a 50% for my set up. I'd like a slow graceful lock during normal driving.
I have noticed that during 3-4 gear shift the engine seems to hold rpm breifly then bangs into 4th. I was thinking a broken 3-4 accumulator spring. However, yesterday during a WOT 3-4 shift, it was fine. Is it possible that line pressure is low? It's much worse when it's cold. _________________ Andy
The TCC lockup is controlled by line pressure also. If the line pressure is too low you don't get good control. I would increase your 3-4 line pressure to correct the hanging on the 3-4 shift first. To soften the tcc apply first make sure PWM output #2 is defined as TCC Pressure Control. Set you starting duty cycle to 0, your ending duty cycle to 95, your lockup rate around 20 and your unlock rate at about 500. You should then be able to see the duty cycle ramp up during lockup. Raise the starting duty to just before lockup actual begins. Usually around 35%.
I did what you suggested. 3-4 is no longer a problem. I also ended up increasing psi across the board which provided better shifts as well. However, TCC apply at 19%, 30% and even 10% is worse than before. It's pretty much like shifting into a gear in a standard transmission and side stepping the clutch. This is during (the worst) 5-25% tps. My TCC starting duty cycle is 23% and feels like it locks the second I touch the gas after coasting. PWM 2 is set for TCC. I can't get a softer TCC apply unless I drop line pressure a lot. Do I need another calibration? _________________ Andy
I'm having a hard time finding what the pulse width modulation frequencies are for all solenoids in my 1998 4T65E non-HD. It's out of a 1998 Buick LeSabre 3800. Do you have any information about this?
I also did some research and applied what I learned in school, and figured out that TCC duty cycle was set too high. I brought it down from 68 Hz to 24 Hz and no more snappy buck buck! It's all nice and smooth now. What a thrill! Finally got it!
My service manual says the TCC frequency is 32 Hz. That explains why lock up was always so harsh. Also, looking at my line pressure graphs (psi vs. temp, and load vs. psi), it seems like I've had to add a ton of psi to get firmer shifts. I know why now. In the calibration, the frequency for the EPC is 490 Hz. According to the service manual, it is supposed to be at 292 Hz. More frequency = more duty cycle = more fluid is passed into the exhaust port creating less pressure. Is there a way I can lower my EPC frequency so I can achieve more line psi? I've tried, but my wiring limits me from changing to different clocks. _________________ Andy
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