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Hi, I am battling a larger problem but stumbled across this possible symptom/cause and could REALLY use a professional's help.
1999 TransAm H/C/I A4 with 3.73's and 3400 stall.
My question: While normal driving and watching the PCM with my Tech II, I see the PCM command the transmission TCC to LOCK, but sometimes (most of the time) it does not lock for a long time until I hit around 40% throttle position, which it then clearly and solidly locks and stays locked until the unlock command. What would cause this?
It's not locking at all, the converter is a high stall and remains super loose with hundreds of RPMS of slip both positive and negative while above is happening and driving normally.
Pasting a screenshot of my HPTuners settings in case it's something there but I don't think it is because one of my tests was to copy all the transmission settings from another similar car which is working fine and my car still did the above.
No slips at all when locked even under heavy load otherwise.
Someone please tell me it's just a solonoid I can change?
The larger problem I am having is that occasionally it will go into LIMP mode where it shifts hard and TCC stops locking, and then apparently overheats the transmission and pukes out the vent tube, I have no clues on this one yet so chasing this initial symptom. If someone who knows these transmissions can actually link those two events with a good probable cause I'd be super appreciative, as this has left me stranded at 1am about 100 miles from home recently when I boiled all the fluid out the vent tube on a trip. $350 tow.
For some reason I can't see your pic. Can you monitor the "TCC SLIP" while driving and see what it reads? How long ago did you install the converter? Throwing any codes?
For some reason I can't see your pic. Can you monitor the "TCC SLIP" while driving and see what it reads? How long ago did you install the converter? Throwing any codes?
When I monitor the TCC slip, it shows hundreds of RPMS of positive slip as well as quite a bit of negative slip (on deccel) when the "problem" is happening. So I really don't think it's a partial lock that's slipping, it's way too loose. When locked, the slip is like single digits or zero. Very solid even heavy throttle uphill.
Trying to attach the pic a different way, zipping it so it doesn't render inline.
EDIT: trans and converter are about a year old, I think I noticed the TCC delayed lockup problem months ago though. Just wasn't sure until I scanned it, and didn't need to scan it until recently when I had the boil over leave me stranded LOL.. and no codes.
EDITED: One more quick symptom, before the boil-over months ago it actually was behaving a "bit" differently. When accelerating up a long steep onramp (normal acceleration, not WOT or anything), it actually wouldn't lock AT ALL until I completely let off the throttle (0%) and then reapplied the throttle, even at 70mph. I've been farting with the tune so not sure if the symptom changed because of my changes or if the boilover had something to do with it. Now since the boil over, I don't believe I even have to release the pedal, I just need to eventually bring the throttle up to around 40% and it then locks solid.
I actually liked that behavior because it allowed me to "save" the converter clutch from powering through an uphill lockup which I felt saved clutch wear. I'd peak the hill and next application of throttle it'd lock under light load.
I am going to drop the pan and test and maybe even swap out the two TCC solonoids I think, I'll try to check harness and other junk while I'm in there, will be swapping to a pan with drain plug and new filter.. Builder was a bargain builder who cranks out a ton of 4L60Es. The fact there's a high stall and custom tuning makes him not want to really work with me on it (warantee's out so I understand. Trans builders just want to nuke from orbit and rebuild... I get it. I just want to see if I can fix it without a rebuild).
I don't even care that the TCC is behaving this way, but the car left me stranded as I described and I need to trust it again. This is the only odd symptom the transmission is having so hoping if I fix this it'll fix whatever did the limp mode.
Also, trans and TC are a year old but there's a ton of miles, maybe 40-50k. This is my DD I use for work and need to get it reliable again so I can keep driving her :-)
EDITED: One more quick symptom, before the boil-over months ago it actually was behaving a "bit" differently. When accelerating up a long steep onramp (normal acceleration, not WOT or anything), it actually wouldn't lock AT ALL until I completely let off the throttle (0%) and then reapplied the throttle, even at 70mph. I've been farting with the tune so not sure if the symptom changed because of my changes or if the boilover had something to do with it. Now since the boil over, I don't believe I even have to release the pedal, I just need to eventually bring the throttle up to around 40% and it then locks solid.
I actually liked that behavior because it allowed me to "save" the converter clutch from powering through an uphill lockup which I felt saved clutch wear. I'd peak the hill and next application of throttle it'd lock under light load.
I am going to drop the pan and test and maybe even swap out the two TCC solonoids I think, I'll try to check harness and other junk while I'm in there, will be swapping to a pan with drain and new filter.. Builder was a bargain builder who cranks out a ton of 4L60Es. The fact there's a high stall and custom tuning makes him not want to really work with me on it (warantee's out so I understand. Trans builders just want to nuke from orbit and rebuild... I get it. I just want to see if I can fix it without a rebuild).
Also, trans and TC are a year old but there's a ton of miles, maybe 40-50k. This is my DD I use for work and need to get it reliable again so I can keep driving her :-)
I'm not 100% positive on your issue. Certainly you want to immediately stop overheating the trans. Are you monitoring the trans temps? There's a common issue with the A4s in these cars. Immediately after installing my converter I got a P1870 code. I had to replace the TCC valve in the valve body. You do NOT have to remove the trans and i suggest doing it regardless. Especially since you're dropping the pan.
I'm not 100% positive on your issue. Certainly you want to immediately stop overheating the trans. Are you monitoring the trans temps? There's a common issue with the A4s in these cars. Immediately after installing my converter I got a P1870 code. I had to replace the TCC valve in the valve body. You do NOT have to remove the trans and i suggest doing it regardless. Especially since you're dropping the pan.
Yes, I monitor the trans temp like a hawk now. Anything over 220 and I stop and let it cool just to be safe. But that's no way to live :-)
I "think" when I am on a slower road, the car gets in this "commanded lock but unlocked mode" (and previously I am unaware because without scanning how would you know?) and then after a while of this it goes into limp mode. I was able to replicate it one time while watching it to see how long it would stay in "lock commanded but unlocked" mode and after maybe 3 or 4 miles it went into limp mode where it shifted hard and no TCC at all, and the temp started rising. I stopped and let it cool down. Haven't let it go into LIMP mode since.
It only boiled over that one time because it was 1am and it was a dangerous highway and I did not want to sit on the berm, I drove it in LIMP mode to next offramp and it puked its guts out. I thot it was dead, but once towed home and I replaced fluid and started scanning/testing, it seems perfect except for this TCC problem which I suspect is the root of all its problems.
This is what I used after several forum experts guided me towards it. I dont believe its your problem 100% BUT I would do it regardless.
There are a few decent YouTube videos of the install.
Thanks for the tip. This is my 6th A4 Fbody... I actually had that leakdown TCC problem you describe from the worn barrel in a prior car, I think that's this valve fix you mention.. but I really think this is different. When it locks, it's locked SOLID and stays there, at least for 40 miles in one long highway test I did. Will consider this though... maybe it needs extra pressure behind the TCC valve you describe to move it? You're probably right, $20 and doesn't look tough to do, maybe do it anyway. Anyone else have ideas I'd love to hear.
Who did your tune? I'm sure the experts will see this post soon and offer much better help than I can.
Tune was all me. But I copied the trans stuff from a Frost tune and also tried to copy another similarly equipped Camaro trans settings and same behavior. Thanks for the input though... any back and forth is good and helpful. It's all food for thought!!!
This is what I used after several forum experts guided me towards it. I dont believe its your problem 100% BUT I would do it regardless.
NEW INFORMATION:
I was assuming the trans was going into LIMP mode because of the computer commanding TCC lock but the TCC didn't lock for a long time.
Today I tuned it so the TCC command would only occur above 65 MPH, thinking I can babysit it on the highway and this would allow me to cruise around town and buy me some time and use the car.
Apparently I was WRONG. I never reached 65MPH and it went into LIMP mode anyway within 10 miles of driving. AND it finally threw a code while it was in LIMP mode. Finally got a code!!
P1870
So Tyler I am going to take your advice and start with that fixer valve you pointed me to, and while I'm in there I'll ohm test all the solenoids and eyeball the harness etc. We'll see if that fixes her.
I understand that the P1870 is a strong indicator for that valve but not sure how it could trigger when I never commanded the TCC to lock (I don't think). So fair chance I have another problem... I need to google and see what else "could" cause that P1870 just to prepare for possible next step, but I am going to put that valve in anyway. Heck, it's only $20 and from the videos I think I can do it myself.
Any other input from anyone would be greatly appreciated.. I suspect I'm not getting a lot of pro replies because they're all off the clock for the weekend LOL.
I was assuming the trans was going into LIMP mode because of the computer commanding TCC lock but the TCC didn't lock for a long time.
Today I tuned it so the TCC command would only occur above 65 MPH, thinking I can babysit it on the highway and this would allow me to cruise around town and buy me some time and use the car.
Apparently I was WRONG. I never reached 65MPH and it went into LIMP mode anyway within 10 miles of driving. AND it finally threw a code while it was in LIMP mode. Finally got a code!!
P1870
So Tyler I am going to take your advice and start with that fixer valve you pointed me to, and while I'm in there I'll ohm test all the solenoids and eyeball the harness etc. We'll see if that fixes her.
I understand that the P1870 is a strong indicator for that valve but not sure how it could trigger when I never commanded the TCC to lock (I don't think). So fair chance I have another problem... I need to google and see what else "could" cause that P1870 just to prepare for possible next step, but I am going to put that valve in anyway. Heck, it's only $20 and from the videos I think I can do it myself.
Any other input from anyone would be greatly appreciated.. I suspect I'm not getting a lot of pro replies because they're all off the clock for the weekend LOL.
Its not too difficult. Just bend the clip ends together, spread the clip as a whole, and pry on the valve. You're essentially pushing the valve through the clip that you spread. The videos don't really explain it very well IMO. They pinch the clip and pry. I had way better luck bending the ends straight and spreading as wide as I could and prying the valve sideways and out. Buy a tiny needle nose, I had to grind my needle nose down to get access even though it was already pretty small.
Hi, I am battling a larger problem but stumbled across this possible symptom/cause and could REALLY use a professional's help.
1999 TransAm H/C/I A4 with 3.73's and 3400 stall.
My question: While normal driving and watching the PCM with my Tech II, I see the PCM command the transmission TCC to LOCK, but sometimes (most of the time) it does not lock for a long time until I hit around 40% throttle position, which it then clearly and solidly locks and stays locked until the unlock command. What would cause this?
It's not locking at all, the converter is a high stall and remains super loose with hundreds of RPMS of slip both positive and negative while above is happening and driving normally.
Pasting a screenshot of my HPTuners settings in case it's something there but I don't think it is because one of my tests was to copy all the transmission settings from another similar car which is working fine and my car still did the above.
No slips at all when locked even under heavy load otherwise.
Someone please tell me it's just a solonoid I can change?
The larger problem I am having is that occasionally it will go into LIMP mode where it shifts hard and TCC stops locking, and then apparently overheats the transmission and pukes out the vent tube, I have no clues on this one yet so chasing this initial symptom. If someone who knows these transmissions can actually link those two events with a good probable cause I'd be super appreciative, as this has left me stranded at 1am about 100 miles from home recently when I boiled all the fluid out the vent tube on a trip. $350 tow.
Thanks guys.
For the last week or so, I have not been able to view photos on this website...
Please post a hyperlink to the photo for me if you can.
The slip RPM and percentages are most of the time a metric/ parameter of no value.
The later model 4L60E units that had both a input speed and output speed sensor did actually give some data of value.
The use of an aftermarket "High Stall Speed" torque converter will only make this data more worthless.
The Diagnostic Trouble Code that you have had set, is a generic "component slipping" code.
The PCM has approximated this information as it has no actual way to compare data from sensors to calculate/ perform math from data to detect "slipping".
The later units with ISS go about this in a much better way.
Also it is common to require a re-tune/ have DTCs ignored regarding "slipping"... The higher stall speed of the torque converter can not be differentiated from an actual slipping component (especially in the earlier units).
It is absolutely advisable to test and make sure that the lock-up clutch can apply and hold lock-up.
This is where I would start... and then go about having a tune done for the transmission.
I also see that the transmission has overheated...
If the torque converter is not locking-up, the transmission will overheat.
Hopefully you have added an addition ATF cooler along with the "High Stall Speed" torque converter.
The transmission overheating can also prevent the lock-up command...
It is time to start checking that the TCC lock-up function operates electrically (bench test if you will) and hydraulically.
If you do not wish to dive in yourself... then it is time to visit a transmission shop.
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4L60E TCC strangeness (PIC attached) 
