torque converter - Q

Chris74 · #1 Thu, February 5th, 2009, 11:48 AM

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, 12:06 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, 01:52 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, 02:03 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, 02:34 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, 02:37 PM

Hey... gotta keep things interesting, right?

***Jackpine*** · #7 Thu, February 5th, 2009, 02:42 PM

Chris, you might try reducing your 4-3 downshift and 4-3 TC unlock speeds. I tried this and it seemed to help that overly eager desire to downshift or unlock. But, I haven't really been where I could test it properly yet. This is the same problem Twintips was talking about too. It's almost as if Ford engineers thought we wanted to hear our engines rev. (Like you, I'd just as soon it didn't unless I REALLY wanted it).

- Jack

Chris74 · #8 Thu, February 5th, 2009, 07:07 PM

Quote:

Originally Posted by JackandJanet

It's almost as if Ford engineers thought we wanted to hear our engines rev. (Like you, I'd just as soon it didn't unless I REALLY wanted it).

- Jack

Jack - Exactly.....my thoughts right to a tee as well!

I was able to do what Bill said and have determined that is definitely my TQC coming unlocked........it's not a down shift! Engine revs higher and rpm's climb about 3-400 or so.
So now what?............do I just reduce the TQC unlock setting or increase it? How much should I start with. Like I said, I want to be able to gently pass a car without it unlocking!

***Jackpine*** · #9 Thu, February 5th, 2009, 07:20 PM

Great! I BELIEVE, you reduce the TC unlock settings on 4-3, 3-2, etc. I think this inhibits unlocking until the speed is lower and the engine is under more load.

If I'm wrong, the Mad Doctor will jump right in here and set me straight! But this seems like the way it works to me.

Note: I've also decreased the TC lock speeds on upshifts.

I changed them all to the max. I really haven't been in a situation to properly test them, but my limited driving over some hills seems to feel right.

- Jack

***Power Hungry*** · #10 Thu, February 5th, 2009, 11:39 PM

You've got it right, Jack. Drop the 4-3 TC downshift a couple MPH at a time and give that a shot. If it helps, then we can make similar changes to the strategies in your custom files so you don't have to reload them every time you change a level.

Let me know how it works and where you end up.