torque converter - Q

Chris74 · #1 Thu, February 5th, 2009, 01:48 PM

Can some body take the time to explain to me exactly how the TC is supposed to function. I'm not really sure if I should be playing with my custom setting for the locking and unlocking of the TC but I'm not totally happy with how easy my truck seems to want to downshift.
I usually run my 87 performance tune and it seems like the truck is more willing to downshift from 4th to 3rd then when it is in stock form??? Is this normal?
I just have to breath on the pedal and it downshifts to 3rd. The power is great but not always necessary. When cruising and pulling out to pass just one car.......I would like to be able to just nicely lean on the peddle to go by him without the downshift if it's not really required. I can understand it if I really come on to it, or even moderately...........but should it gear down when slightly shoved?

Or is this even a TC unlocking issue at all?
thanks,
Chris

kokopellimotorsports · #2 Thu, February 5th, 2009, 02:06 PM

Probably not a torque converter issue at all. Sounds like a transmission shifting strategy issue. Bill can change this fairly easily, you just need to get into contact with him. When the torque converter unlocks it should only change your r.p.m by about 300 r.p.m, whereas a downshift will change by about a 1000 r.p.m. When the torque converter locks it no longer has a fluid coupling between engine and transmission, but now has a more mechanical connection, kind of like a clutch on a 5 speed. Well I hope this helps.

Ty

***Power Hungry*** · #3 Thu, February 5th, 2009, 03:52 PM

Chris,

Change one of your display PIDs to "GEAR". This will display the current gear and also indicate if the converter is locked or unlocked by a little "lock" symbol on the display. This will help you determine if the problem is downshifting or converter unlocking.

Once the problem is identified, we can modify the offending parameters to resolve the issues.

Take care.

kokopellimotorsports · #4 Thu, February 5th, 2009, 04:03 PM

Quote:

Originally Posted by Power Hungry

Chris,

Change one of your display PIDs to "GEAR". This will display the current gear and also indicate if the converter is locked or unlocked by a little "lock" symbol on the display. This will help you determine if the problem is downshifting or converter unlocking.

Once the problem is identified, we can modify the offending parameters to resolve the issues.

Take care.

Forgot about the PID's. Oops!

Chris74 · #5 Thu, February 5th, 2009, 04:34 PM

okay, thanks guys!

I'll do that and get back to you Bill. I hope it doesn't involve re-tuning........you just made some adjustments to my tunes

***Power Hungry*** · #6 Thu, February 5th, 2009, 04:37 PM

Hey... gotta keep things interesting, right?

Dfishrmn · #7 Sun, February 15th, 2009, 07:49 PM

Quote:

Originally Posted by Power Hungry

Chris,

Change one of your display PIDs to "GEAR". This will display the current gear and also indicate if the converter is locked or unlocked by a little "lock" symbol on the display. This will help you determine if the problem is downshifting or converter unlocking.

Once the problem is identified, we can modify the offending parameters to resolve the issues.

Take care.

I have noticed on my PID the only gear I get the "lock" symbol is in 4th. None of the others show it no matter what speed or load. Is this normal?

JWBFX4 · #8 Sun, February 15th, 2009, 08:39 PM

Quote:

Originally Posted by Dfishrmn

I have noticed on my PID the only gear I get the "lock" symbol is in 4th. None of the others show it no matter what speed or load. Is this normal?

well after reading this and trying to think about mine...I can only remember seeing it in 4th but I could be wrong

but I am sure someone will have the answer.

Sburn · #9 Sun, February 15th, 2009, 09:30 PM

Quote:

Originally Posted by JWBFX4

well after reading this and trying to think about mine...I can only remember seeing it in 4th but I could be wrong

but I am sure someone will have the answer.

If you take your truck out of overdrive (OD), and are running at a constant speed, you should see 3rd gear lock as well. At least that what it does on my 2007 4.6