Would a vacuum modulator also affect TCC apply pressure?
08-20-2005, 02:22 AM
#1
Would a vacuum modulator also affect TCC apply pressure? Cliff Notes:
Back in June I installed a brand new FLP tranny and a brand new TCI 3800 stall torque converter. From that very day, I couldn't get the TCC to lock up when it was supposed to. I removed all low/medium rpm misfire settings (very high numbers). I tried to force it thru my HP Tuner cable, no luck. I took it to a local tranny shop and they hooked up their Snap-On diagnostic tool to it, and it says the PCM is trying to lock it up. It's just not happening. I've even sent the torque converter back to TCI for inspection. Worked fine for them. They disassembled it to look at the inside and found nothing wrong with it at all. So now I'm down to just the tranny itself. I don't know how far I'm going to need to get into this, but I'd like to act on it as soon as my converter shows back up the end of next week.
So I need some info first.
Does the TCC apply pressure control off of the PCM on a vacuum modulated 4L65E tranny, or is it run off the vacuum modulator?
If I need to get into the pan and test the TCC solenoid, where is it? Do I have to pull the valve body?
I read something a long time ago about pulling out the thing at the very tip of the input shaft to allow the converter to get more fluid. Anyone ever try/recommend this?
A friend of mine who builds trannys says that if you pull the solenoid and put in a check ball, re-assemble and re-fill the tranny, start the car and put it in gear, if the car stalls than the tranny/converter is capable of locking up. But that seems like an aweful lot of running around for this...
Back in June I installed a brand new FLP tranny and a brand new TCI 3800 stall torque converter. From that very day, I couldn't get the TCC to lock up when it was supposed to. I removed all low/medium rpm misfire settings (very high numbers). I tried to force it thru my HP Tuner cable, no luck. I took it to a local tranny shop and they hooked up their Snap-On diagnostic tool to it, and it says the PCM is trying to lock it up. It's just not happening. I've even sent the torque converter back to TCI for inspection. Worked fine for them. They disassembled it to look at the inside and found nothing wrong with it at all. So now I'm down to just the tranny itself. I don't know how far I'm going to need to get into this, but I'd like to act on it as soon as my converter shows back up the end of next week.
So I need some info first.
Does the TCC apply pressure control off of the PCM on a vacuum modulated 4L65E tranny, or is it run off the vacuum modulator?
If I need to get into the pan and test the TCC solenoid, where is it? Do I have to pull the valve body?
I read something a long time ago about pulling out the thing at the very tip of the input shaft to allow the converter to get more fluid. Anyone ever try/recommend this?
A friend of mine who builds trannys says that if you pull the solenoid and put in a check ball, re-assemble and re-fill the tranny, start the car and put it in gear, if the car stalls than the tranny/converter is capable of locking up. But that seems like an aweful lot of running around for this...
08-20-2005, 08:20 AM
#3
The vacuum modulator replaces the force motor which is what the pcm signals to raise or lower line pressure, so yes it controls pressure that controls tcc.
But if you have enough pressure to drive it without third or fourth slipping it has enough pressure to apply the tcc.
Putting a check ball above the solinoid (on a 700R4 anyway) would make it lock up above second gear.
I wouldn't take the checkball capsule out of the input shaft tip. It's not going to help if it's not locking up and if you do get it to lock up it will probably be too harsh without it.
Did you ever discuss this tcc problem with the trans builder?
I'd pull the solinoid out and the lockup valve to check for proper assembly, etc.
Then check the solinoid operation, clean it off and blow through it, air should go through, then apply 12 volts, air should stop.
The solinoid is the only thing in the pump with wires going to it, so the pan does need to come off.
But if you have enough pressure to drive it without third or fourth slipping it has enough pressure to apply the tcc.
Putting a check ball above the solinoid (on a 700R4 anyway) would make it lock up above second gear.
I wouldn't take the checkball capsule out of the input shaft tip. It's not going to help if it's not locking up and if you do get it to lock up it will probably be too harsh without it.
Did you ever discuss this tcc problem with the trans builder?
I'd pull the solinoid out and the lockup valve to check for proper assembly, etc.
Then check the solinoid operation, clean it off and blow through it, air should go through, then apply 12 volts, air should stop.
The solinoid is the only thing in the pump with wires going to it, so the pan does need to come off.
