Engine/Transmission (1998.5 - 2002) Torque Converter prematurely locking up at

[Challenger-II]

OK... ... I am not sure if my trans is working right or ready to take a $%$# . This thing loves to be in lockup! I always run with the OD button out when doing speeds below 55mph and engage OD when above. The problem is that the converter locks up at a speed of 26-28 mph when out of OD! This even happens if I am going up a hill... . which is exactly when you don't want it to happen. I have to really mash the go pedal to get it to kick out and down, but it just locks back up soon after the truck shifts to 3rd. I just think that locking up at 28 mph when climbing a hill is lugging things. Is this normal??? When locked up at 28 mph, its not very responsive to acceleration unless I really mash it. Good thing is when I accelerate while lugging... . my converter is not slipping. Any opinions?? THANKS!

 

[emjay]

That seems a little slow, should be about 35 MPH with OD disabled. Do you have 4. 10 gears? If so, that may be about right. Anyone else?

 

[fest3er]

If I had to guess, I would say your throttle valve cable needs adjusting. Or perhaps your TPS is malfunctioning.

My '98 12V auto will lock up at 25 MPH if I'm *barely* on the throttle (i. e. , TPS says *just* off idle). But under normal (old lady) acceleration, it won't lock up 'til 32-38 MPH. Under WOT acceleration, it won't lock up 'til 50 or so.

In any case, your truck is not functioning quite correctly. Hmmm. I might suspect the TPS before the TV, since the PCM controls lockup, and the TPS 'drives' the PCM; the TV is a trans-only input.

Fest3er

 

[LSMITH]

Mine does the same thing under light throttle, and it does not bother me a bit. I drive it all the time at 1100-1400 rpm locked up. If you can add fuel and get the engine to increase rpm you are not lugging it, PERIOD. Not saying that running around at 1100 RPM is good for it, but you will not hurt the engine doing it. It "can" be hard on drivetrain parts IF you nail it as the torque pulses are quite strong and auto transmission pressures are low.



Things to keep in mind. Your PCM has no idea what the HP of your engine is. EACH and EVERY mod you do that increases HP gets farther and farther from what the programming was set up for. Your PCM thinks you have 215-235 HP, and that you are only using a very small part of that at light throttle when you may be making lots more than it knows about. This is what causes the early (in your opinion) lockup and gives guys the ability to thrash their auto trannies in very short order. This is also why it has become the rule to lock out OD below 1500 RPM. If you know how and why it works the way it does, and you drive according to the conditions, you will not hurt anything driving in lockup at low RPM.

 

[Challenger-II]

I am not running any mods and it is doing this... . bone stock. I have a 3. 54 rear. Even If I am in OD, she locks up just the same in 4th at around 43-45 mph. I was accelerating to get on to the highway tonight and she locks up at 45 mph dropping my rpm's and in my opinion... . the power. It should wind out a little more! :{



fest3er..... is the throttle valve cable adjustment easy to check??

 

[LSMITH]

Hmmm, doing this bone stock? What amount of throttle is used when it is locking at when at low speeds? If even at half throttle it should not lock until it is about 40 in D and about 55 in OD. At WOT it should lock at about 60 in D and 82-85 in OD, all the above for 3. 5 gears. Set up a signature, it will help with info.

 

[Extreme1]

What year is your truck? My '94 does it, most 94-95's do it.

 

[Challenger-II]

Originally posted by LSMITH

Hmmm, doing this bone stock? What amount of throttle is used when it is locking at when at low speeds? If even at half throttle it should not lock until it is about 40 in D and about 55 in OD. At WOT it should lock at about 60 in D and 82-85 in OD, all the above for 3. 5 gears. Set up a signature, it will help with info.

My truck is a '99. Your right..... I need to set up a signature



It locks up in D especially at light throttle but will also lock up while under moderate acceleration... even going up a hill. If I am really into the throttle, it won't lockup until the higher mph (40??) but, I cant always be heavy into the pedal to get it to lockup later... I'll end up in someones trunk!

 

[LSMITH]

I think it is working like it is supposed to.

 

[jbone]

As you can see from sig. I'm driving 99 also---mine has 4. 10 and doesn't lock-up until 40--if I'm poking along (not much of that with the EZ!!). When I'm normally accellerating locks up at 50 or so..... I would think your going to destroy T. C. sooner than need be---we will all have to replace T. C. sooner or later, just want mine to be later!?! Might want to check pressure on the transmission--see what kind of pressure you are reading??? R, J. B.