Trans TCC?!

[multishowner]

Good day all,

I got my SHO on the road not too long ago after doing an entire engine rebuild. I had a prob with the Alt, but that was short lived as the new one is holding up nicely. I am having a prob with the TCC in the trans... Make no mistake, the trans itself is doing great! No hesitation between shift and stays in until just before redline for each gear... No noises of any kind, either! The prob I am having is that the computer is engaging the TCC within seconds after it hits third and again in fourth, regardless of pedal position... I hit the brake doing a constant 60 or so, like the book says and I am not getting a positive release of the TCC... I have changed the fluid and filter using Ford Mercon V... Get this, I have pulled the wire for the TCC that goes back to the computer and I don't get any pulsing or shudder of any kind... The TCC just doesn't engage and the O/D OFF flashes as it should... I have been running it like that because I don't go far to work and I like the fact that the car has power forever, but at the small expense of using more gas... Well, I have someone that wants to buy it and requests it work as it should... Anyone out there have an idea as to what is causing it? Is the computer not giving a good ground? Is the TCC solenoid toast? Is it the TCC itself?
Thanks in advance!!

 

[SHOZ123]

So you are saying the TC is locking up within seconds of an up shift? If so this is a good thing. The only time the TC should not be locked and slipping in 3rd or 4th is after an up shift or when lifting off the throttle idealy. This is not how it is programmed from the factory though.

 

[multishowner]

From my understanding on the Torque Converter Clutch is that it should engage when the car reaches it's desired cruising speed... anything other than mild acceleration, it should disengage to allow the torque converter to multiply the power... Any full throttle acceleration should not only disengage the TCC, it should also drop to third until redline, and stay disengaged in fourth until full throttle is no longer present...

Regardless of when it engages, it doesn't stay engaged, even when cruising at 70 with Cruise Control on... I believe this is where the heat build-up is happening, and not just in my SHO, to the extent of overdriving the factory cooler...

 

[wuzzzer]

From my understanding on the Torque Converter Clutch is that it should engage when the car reaches it's desired cruising speed... anything other than mild acceleration, it should disengage to allow the torque converter to multiply the power... Any full throttle acceleration should not only disengage the TCC, it should also drop to third until redline, and stay disengaged in fourth until full throttle is no longer present...

Sorry, that's not how it works.

If you are at WOT and the TQ convertor locks, if you very quickly lift your foot off the gas and then stomp it back down the TQ convertor will unlock but it will lock up again after a little bit. Some people call this the 'lift trick.'

There was a big discussion a while back on the V8 SHO email list as to whether or not doing the 'lift trick' would be beneficial in a 1/4 mile race. Obviously you're going at WOT the whole 1/4 mile, right? Some were experimenting with this lift trick because at about 80 mph the TQ convertor locks up no matter how hard you're mashing the gas. Doing this gets the revs up just a tad higher than when the TQ convertor locks up. End conclusion was that it didn't help or hurt 1/4 times (I believe)

 

[multishowner]

Interesting... When mine tries to engage, I think it actually slows me down because the engine is not operating in the higher RPM's.... I didn't actually do times when I had it hooked compared to when I was running with it disconnected... I pulled the TCC return from the top of the connector... It was full power until redline the entire time... I don't know my top speed in this SHO because the speedo quits at 110... The Ford book says if you hit the brakes it also should release the TCC... I guess if you could push the brake pedal enough to light the lights, it should keep the TCC off the entire time. Not too sure if that will work at WOT...

 

[wuzzzer]

If you're cruising at a constant speed, say 50mph or so, and you take your foot off the gas and then re-apply it, what does the tachometer do?
In my car (and I'm assuming every other Gen 3 is the same) convertor unlocks and the RPMs will rise about 300-400. Then when the convertor locks up they'll drop back to where they were before.

As regards to the convertor unlocking with the brake, someone once experimented with wiring up a switch so that he could make the engine computer think the brake pedal was being pushed and so prevent the convertor from locking up. I'm not sure if he was successful, though.

From what you're describing, your car is functioning completely normal. Torque convertor locks up in 3rd and 4th at WOT, at partial throttle and everything in between.
Unless I'm missing something?

 

[multishowner]

It does the unlock and then locks... It looks like the TCC is working the way it should, with one exception... When it locks, it doesn't STAY locked... I don't know if the computer wiring is faulty or it is the solenoid, or even the TCC itself... There is no rhyme or reason to the way it acts... It is engaging when it should, from what you say, but releases a little, allowing slippage, then re-engages fully... it does this cycle fast or slow, but never stops the cycle... It will never, not let go, after it engages, if I am just cruising at, say 70...

 

[SHOZ123]

When the TC is unlocked it is slipping. The rpms will be higher. With the TC locked you get the most power to the wheels.

The TC will cycle with OEM programming on and off when cruising with the climate control in a mode where the A/C compressor is used. The TC will lock up in 3rd and 4th gears.n You can tell it locks by driving at a steady throttle and speed and watch the rpms drop a couple hundred.

It the TCC is off and the TC is slipping you will build up the heat. If this is a mechanical or electrical problem you will also set a DTC 1744. this is set after the TCC stops trying to hook up.