Freezing the Slushbox. Torque Converter on-demand lockup switch.

[ksa8907]

I was going to make a new thread but decided to keep everything here. I wired in a voltmeter to my TCU on the control for the LR/CC solenoid. In first, reverse, and neutral I read 8-9the volts, every other gear is B+, converter lockup at cruising speed is between 10.4 and 11 volts. Should I assume I need to switch this wire to ground?

[skeeterb]

I just thought of something, if you monitor all the wires on the lines going into the transmission and do whatever it takes to engage the right brakes/clutches at the right time, you could use a simple switching system like the ones you see on arcade games like the Crusin' games (Crusin' USA, Crusin World, Crusin' Exotica). You could use a simple program on a microcontroller to engage the right clutches to make it go to the different gears. This would probably work on a car with an older model car. I'm not sure that it would work with the newer cars because they are so complex in how they operate because more and more stuff is hooked into the car's computer. This is just an idea, but i just wanted to put it out there.

[ksa8907]

nooooooo, just re-read some stuff on allpar saying that for the a604, predecessor to the 42le, you will burn out solenoids if you ground them. looks like ill be building a circuit.

[mikeyjd]

Any reason not to try this on my wife's intrepid?

[XYZ]

Originally Posted by mikeyjd

Any reason not to try this on my wife's intrepid?

Umm... Divorce?

[ksa8907]

I gave up on the idea. Seemed a bit risky to play with the tcu directly, plus the advantage would be no slipping at high loads but that would probably tear up the clutch since its small. Going to get a new gauge cluster this week so I can use autostick instead.

[RH77]

Originally Posted by ksa8907

you will burn out solenoids if you ground them. looks like ill be building a circuit.

Are they referring to the clutch solenoids for gear change and/or the torque converter solenoid(s)? If you can get a hold of some schematics for TCU/TCM output, it may be possible to find the voltage to energize the proper solenoid(s) at the flick of a switch, while isolating the TCU from that operation. It will likely throw a code... plus I would recommend setting-up a switch/circuit to go back to stock for decel, shifting, etc. You could get complex and use the speed sensor, RPM, current gear, TPS, and wire-up a fail-safe mechanism.

This mod can can cause harsh shifting, engine lugging, and other manual trans-like behavior -- including the good stuff, like control over the TC and better FE.

Best FE...
RH77

[japcarmaniac]

did anybody every make good progress on this? specifically controlling gear changes manually and engaging and disengaging the TC like a clutch?

[ksa8907]

If you know how to build circuits, its cake, otherwise its going to be challenging. I gave up.

[RH77]

Originally Posted by japcarmaniac

did anybody every make good progress on this? specifically controlling gear changes manually and engaging and disengaging the TC like a clutch?

Well, sort of. My mod is simply a switch to energize the 2 lockup solenoids with 12VDC, which allows TC lockup and signals the TCU to just up-shift at the lift of the go pedal (that is, when conditions permit -- throttle position dictates hydraulic pressure to engage varying degrees of lockup and is dependent upon the stock circuit to monitor coolant temps on cold starts to restrict short-shifting to higher gears). Every transmission is different, so the trick is to experiment with engine load and type of lockup method.

Despite the effort, that near-direct link between engine and road surface is valuable for FE. Once locked, it stays locked until switched-off... or when slowing down to a near-stall point, partial-lock is mandated and lightly lugs before downshifts (and stays lightly locked while stopped). This still keeps the engine running, but it's under load and forces lower RPM if you forget to disconnect. It's an enjoyable challenge to treat it like a manual and place automatic transmission control back in the hands of the driver.

Once everything is warmed-up, up-shifting is as easy as lifting the throttle (downshifts are accomplished through the shift stalk or harshly through high throttle input). Sometimes it's a bit too aggressive and needs some intervention (engine lugging, direct lock on decel = more compression braking, and finesse with the throttle to avoid excessively harsh shifting, either up or down, is needed). An investment in synthetic trans fluid has helped with any undue stress and/or temps if lockup is delayed or negated since a "stock mode" hasn't been wired for other drivers.

Basically, transmission selector positions 1, 2, D3, and D4 will hold or downshift manually as selected, and upshifts are aggressive enough for me to call it "manual". YMMV.

Have fun...

RH77