Torque Converter Locking/Unlocking

[Smoky1978]

I have a 97 5.0 AWD with around 230k miles. Recently the torque converter will lock and unlock. The O/D light is not on so I am hoping its not a mechanical problem.

I am wondering if there is anything I can test or any suggestion on what the problem could be. Thanks in advance this forum is great.

Well I just ran to the parts store to get codes checked and have P0340 - Camshaft position sensor and P1125 - Throttle Position sensor.

My question is would a bad TPS cause this torque converter behavior?

 

[Dono]

If the od light isn't flashing, I would hope there isn't a problem.

What I found with my 5.0 is that I don't like the factory lock/unlock schedule for the torque converter. In the factory programming, the lockup does not occur on the highway very much. I have been reprogramming my truck ecu with the SCT product and have changed my tc lock/unlock to something that works better for me.

 

[Tedybear]

I have a 97 5.0 AWD with around 230k miles. Recently the torque converter will lock and unlock. The O/D light is not on so I am hoping its not a mechanical problem.

I am wondering if there is anything I can test or any suggestion on what the problem could be. Thanks in advance this forum is great.

Well I just ran to the parts store to get codes checked and have P0340 - Camshaft position sensor and P1125 - Throttle Position sensor.

My question is would a bad TPS cause this torque converter behavior?

TPS can cause issues. If the computer thinks you're going to WOT or back to idle and you are not. That will cause the TCC to act up in some cases (not all, but some)

Remember all the sensors and output devices act in concert with the drivetrain computer. If the computer isn't getting good data, issues and oddities can occur. Not saying this is the cause and there might be other issues, but as a process and finding a direction to follow, might as well address the codes and see if that solves your TCC issue.

Best of luck!
S-

 

[Tedybear]

If the od light isn't flashing, I would hope there isn't a problem.

What I found with my 5.0 is that I don't like the factory lock/unlock schedule for the torque converter. In the factory programming, the lockup does not occur on the highway very much. I have been reprogramming my truck ecu with the SCT product and have changed my tc lock/unlock to something that works better for me.

Did that also solve issues of torque converter shudder/chuggle? I've not had that happen in many years, GM used to call it a chuggle when a customer drove their early models and when the car was 'held' at about 45mph, the TCC would lock up. Create just a hair of drag and drop the speed...TCC unlocks....Drag goes away and the speed kicks up a smidge...TCC locks back up. I can recreate that on our Bronco II quite well at 43-45.

S-

 

[imp]

Smoky, the TCC unlocks every time the driver gets off the gas pedal (coasting). Locks back up (if speed is sufficient) when the pedal is depressed again. Anything fouling up the signal from TPS can cause erroneous information to go to the TCC solenoid. imp

 

[Dono]

I'm to the point where (for my truck) the tc locks and unlocks with no lurching.
I did struggle a bit to get it right. Lots of trial and error till I could 'feel' certain rpms's and load I'd like the tc to lock or unlock a bit faster.
For instance, when I'd let off the gas at certain rpm's the tc wouldn't unlock fast enough and the truck would feel like it had a standard transmission and engine brake. A slight adjustment to the unlock curve and it was fixed.

I will still have some adjusting to do as my 3-4 shift has a bit of a shift flare at very light throttle. I think all I need to do there is add some more line pressure. When I get my motor back in and resume tuning I'll be working at these details.

Its pretty expensive to get the SCT and pro racer package just to work with the transmission and torque converter though.