Tranny and converter work fine when the tranny temp is under 150 degrees, converter locks and unlocks perfectly. As soon as the temp gets over 150, the converter will not lock. The car doesn't throw any codes. Right when I put the converter in, it did a tranny slip code, but hasn't done one since, and I heard thats common when the pcm is getting used to a new converter. Only code my car throws sometimes is a rear bank 2 o2 code, p157 i think. O2 sensor seems to be goin bad. Other than that, no codes. I can't think of any reason why the converter would lock when its under 150 degrees, then as soon as it hits 150, will not lock. If i'm driving when its cool, and the converter is locked, and the temp gets over 150, and I have to speed up and it unlocks, but then I let off the gas and it should lock up again, it doesn't. Makes no sense. And if I keep driving it after it doesn't lock, it gets way too hot running unlocked to drive it any distance.

I just remembered, that the night we put the converter in, it through a couple codes. 2 were the p0100 and p137, which turned out to be from my o2 wiring hittin my headers, and shorting it out. Also, it did a P0719 Brake Switch Circuit - Low Input D *DTC P0719 will be stored in PCM history . Searched and found nothing about it, cleared it and it hasnt' come back since. It also did the p1870, tranny slip code, but hasn't thrown one since either. Anything in there that will help?

Something else I noticed, is that sometimes after driving it awhile, and it gets pretty hot, like around 200, it starts shifting really hard. Like I can be moving at 10 mph, slowly accelerate, and when it shifts to second, it can chirp the tires like a WOT shift does. Once the car cools off, its fine. Any ideas there?

I HAVE to figure this out in the next 2 weeks or so, becuase I have to drive to school and this is my only car.

 

the PCM or TCM should be programmed to cut out tcc and or 4th (depends on the computer strategy) with temps above 230. how are you cheching the temp? scan it and check what the TCM thinks it is running at.

 

I am using my Autometer Transmission Temp gauge. Is there something else I could use to check? Would autotap help? And is there anything that could be tuned to fix that?

 

It's not mentioned above but you did put a tranny cooler on it right?
If not give that a shot...

Plus, if you car is loosing power due to the bad O2 sensor(s) your stall speed and lockup will be different, because they are determind by many things including but not limited to tq, hp, and vehicle weight.. If your loosing power when you get out of Open Loop due to the bad O2(s), you will have less power and vehicle weight will be the same, so you will see a difference in stall speed and lockup. This could be the difference in performance between hot and cold running, Just a thought..

 

Well that gives me something to think about. I know the tranny cooler is put on right, but the o2 info in interesting. I had no idea that stall speed and lockup could be varied by the o2's readings. I'm gonna replace that rear o2 sensor and see if that makes a difference. The only thing is though, that the code comes on and then goes away in a little bit. Comes on very occationally, so I don't think that would be the major cause of this locking problem, but I should replace it anyways. Thanks.

 

I said a loss in power could cause it, not O2 readings, but if the computer pulls timing or richens up the mixture then yes that is cause by O2 readings.
More or less, I guess it depends how you look at it.. But there is nothing in the program that references O2 readings dealing with tranny function...
If the code isn't thrown all the time then I don't know what to tell youbecause performance would only be effected when it is having trouble, and throwing the code, but I could be wrong on that..

Either way I just wanted tro let you know that if there is a power difference that could cause fluctuations in stall speed and the lockup point.. I know because my power steering pump is having trouble, and when I put the AC on as well, it puts such a drag on the engine it is noticable in my stall speed and lock up...

 

The o2 sensor he mentioned getting a code from was bank 2 sensor 2 I believe, so that wouldn't change how the PCM runs the engine would it?

If there was less power, the car would lug more, but it wouldn't change the speed at which the converter locked, or the speed at which the trans shifts. Since they're based off of MPH and that's based on the gears in the diff and the tires on the car.

 

Actually it is also based on throttle position as well, and I don't know about you but a lot of people subconciencely press harder on the throttle when the engine is lugged down. I have scanned my car many different time and found that I press the gas pedal a little harder when there is more of a strain on the motor under normal driving conditions... So in essence making the shift point raise, the converter not lock up untill later, and stall speed runs higher under the exact same condition and driving as when the motor is not lugged down...

I didn't think this much detail was needed in the first posts because it is commenly seen that when the motor is lugged down the throttle is pressed down more to maintain the same speed...