Two weeks ago I installed my new Pro-Built 700-R4, with a 9.5" 2500 RPM stall lockup torque converter also purchased from Pro-Built.

I set the fluid level "correctly" (meaning it was exactly at the top of the HOT range on the dipstick). On my test drive I got some serious torque converter clutch chatter on UNLOCK (not when it locked up, but when it unlocks as I go up a slight hill). Only chatters on gentle unlock, if I stomp the gas it unlocks instantaneously. I added a little more fluid (Pro-Built said running a little bit overfull would not hurt anything) and the chatter got significantly less noticable. However it is still there.

My old converter did have occasional clutch chatter also on unlock.

Now, I have also noticed several times that the converter has failed to unlock when it should. I am driving along at 45 or so, torque converter locked, 4th gear, 1600 RPM approx. I press the gas down slowly, and the converter does NOT unlock. In fact it stays locked until the pedal is down so far that the tranny downshifts. If I press down quickly it does unlock.

My old converter NEVER did this... However it was old (165 thousand miles), and stock, and the clutch engagement spring was probably significantly weaker than the new converter.

I went out and bought a scan tool to try an see what the ECM is doing during this time. I have not managed to scan during the TCC chatter, but I did scan when it was failing to unlock. The scanner reports two values, here's what the manual says about them:

TCC LOCKUP - PCM calculated value. ON = TCC locked, OFF = unlocked. This is a signal indicating whether the Torque Converter Clutch is locked or not.

TCC SOLENOID - PCM output. ON = solenoid engaged, OFF = disengaged. This is a signal from the PCM to the TCC Solenoid to engage and disengage the torque converter clutch. NOTE: This signal merely indicates that the signal has been sent -- it does not indicate that the solenoid and torque converter clutch are operating.

Both values were ON, I.E. the computer SEEMED to be saying that it was telling the converter to stay locked.
So I am wondering if the ECM is insane? Or could it another cause and the ECM values are just reflecting the fact that the TCC is still locked (The documentation for the scan tool could be incorrect, I've noticed other inconsistencies in it).

One reason I am concerned is that I have a transmission overhaul book and it lists in the troubleshooting section "Converter clutch shudder or does not release". Assuming for the moment that we can ignore internal damage to the tranny or converter (since they're both new from a reputable guy), and I already mentioned the ECM as a potential problem, it mainly focuses on low oil pressure in the converter. Low oil pressure can be from low oil level, right? And this brings us to my point. The converter acted better after I "overfilled" the tranny. But my friend was looking at my dipstick and said it was not marked in the same place as the last 700 dipstick he saw! Now, that was from an 86, and we have not had a chance to place the dipsticks side by side and compare, but he claimed the full mark was significantly higher (1.5 inches or so) on the 86 dipstick than the "hot" range on mine. What possible reason for this could there be? Is it possible someone replaced my dipstick with the wrong one (my car had 125 thousand miles on it when I bought it three years ago)? Has anyone looked at multiple 700 dipsticks? My current dipstick is marked with a "cold" range and a "hot" range. The 86 dipstick was marked with an "add 1 quart" mark and a "full" mark. My friend believes that the "add 1 quart" mark on the 86 dipstick was about where my dipstick has the "hot" range.

BTW I want to mention that Pro-Built has been very good about all my questions and trying to help; I'm posting here to get some fresh ideas. He said if we can't get it worked out he can send me a different converter but that would be a huge hassle (for both of us) and all for nothing if the real problem is ECM or fluid level. I want to get it diagnosed correctly before we start replacing parts.

 

Any ideas anyone?

 

Since you stated that the old TC did the same thing, then we can agree that its not the new TC. If you added more fluid and it helped, then lets add another 1/2 quart and see if it improves, then keep adding fluid till the problem is gone. (1/2 quart at a time). Now read the dipstick, and make a new full mark (hot & cold). If it does not change, do not add more fluid.

 

Jeff, honestly this seems almost normal to me. The TCC won't unlock when you slowly roll into the throttle. The throttle must move a certain % in a certain time to get unlock. Or it must pass the absolute throttle % unlock value, which is fairly aggressive in stock 305 bins such that it could be way up near the kickdown.

And yes the TCC is very dramatic not only in a fresh converter, but also a higher stall converter. You will definitely feel it more both when it locks and unlocks.

Dunno, does that make any sense to you. If you have a few minutes i could take a ride with you after work if you want my dumb *** opinion.