4R100 Tranny Upgrade...Need a Program Change?

[cleatus12r]

It doesn't matter at all what the "stall speed" is. If the torque converter clutch is not being applied (but did before the transmission was replaced), then something is wrong with the build. NOT the tuning.

[ChrisCNC]

Thank you for the quick reply, I appreciate it!

Your comment, "If the torque converter clutch is not being applied (but did before the transmission was replaced)...", really got me trying to remember exactly how things have played out.

I purposely avoided that section of the pass (went ~25 miles out of the way to go around it) after I got my bigger tires, and before I upgraded the tranny. I didn't want to tax the stock transmission since my friend smoked 2 stock trannies and I wasn't willing to go down that path carrying my family along.

I went over that section with the stock tires and stock tranny pulling the same trailer before and did not have an issue. The two things that changed this time was the bigger tires (35") and the beefed up transmission. This is the first time over that section of pass with both the bigger tires and the new transmission.

Do you still think it's probably the transmission build? Thank you for your input, I really value it.

Sincerely,

[cleatus12r]

As an example:

If the torque converter clutch applied at 35 MPH (as indicated on the speedometer) with the small tires, then the torque converter clutch apply will STILL happen at an indicated 35 MPH on the speedometer with the larger tires. Nothing will EVER change in that regard unless the tuning is changed or the speedometer is recalibrated. The tires do not change the engine RPM/driveshaft speed relationship; they only change the actual road speed vs. the speedometer.

[ChrisCNC]

Thank you for answering all my questions, I'll head back to the tranny shop!

Any bets on what the problem may be?

[ChrisCNC]

I took time off work this Saturday, hooked my trailer up to the truck and made the ~100 mile roundtrip down to the transmission place that upgraded my transmission. We hooked the system to his scanner to get an idea of what was going on and proceeded to tow the trailer up and down the hills of southwest Eugene toward the coast.

I was able to duplicate the problem readily, between a throttle position of approximately 1.8 - 2.1 volts and a torque of 250 to 300 ft-lbs, if the transmission is in 3rd gear and not in TCL it will not lock up because it is never commanded to. Everytime the TC was commanded to lock up, it did so.

So what happens is this, I'm towing trailer and family over a pass and coming out of a sharp corner or rough patch of road I press down on the throttle and the system shifts out of 3rd w/TCL and into 3rd WO/TCL and it will not go back into TCL because it is never told to. The road is such that I cannot accel up fast enough and if I let off the throttle is slows down too much. Since it is never commanded to lock up the torque converter it does not and the transmission overheats quite quickly on the steep grade.

My tranny guy is more than happy to engage in a phone conversation to help get this system working like should, and better than it is.

Let me know as soon as convenient.

[cleatus12r]

So what you're saying is that you need the torque converter clutch to be commanded to apply at a lower accelerator pedal position in third gear. My guess is that it worked the same way before, but you never noticed it because you never took that trip before.

It's working correctly, just not in the manner that you intend to use it. It sounds to me like we need to play chip tag to remedy your situation.

[ChrisCNC]

Thank you for the reply, Cleatus,

You'd know what the best remedy is I'm sure!

My wife and I got to talking about it and actually, the last time we went over that pass was before we had the custom tunes, it was with whatever came on the gryphon as I had the CTS, but not the custom PHP tunes yet, stock tires, stock tranny.

Let me know how you'd like to proceed. Tony, the owner of Transmisison Solutions, said he'd help as much as possible, including talking with PHP in phone conversations.

Thank you, I appreciate PHP's knowledge and willingness to help... I brag you guys up whenever I get the chance!

Sincerely,