Torque Converter Lock/Unlock

gabeyd · #1 Thu, August 13th, 2009, 04:25 PM

2000 Excursion 7.3 Diesel, PHP Phoenix 40T, 80FS, 80DD

I was under the impression that Bill used PMT1 shift strategies, but I'm seeing my torque converter unlock as soon as I touch the brake. It just makes no since to me, and is one thing I have always disliked about my stock PCM.

I let my foot off the throttle to slow down, the engine does some braking, but it isn't quite enough, so I put my foot on the brake. Now the TC unlocks, and so the engine is no longer helping me slow down, so I have to brake harder. If I let off the brake, the TC re-locks, and the engine slows down again. I hate this.

I thought PMT1 shifts kept the converter locked when decelerating, even if touching the brake petal, at least down to a certain speed...

Why isn't my PHP chip doing this, on every setting, even on the 40T setting (though I have not towed with it yet, this is all tested with just the truck).

Thanks.

***cleatus12r*** · #2 Thu, August 13th, 2009, 08:32 PM

I'll let Bill know of your troubles. He doesn't use PMT1 on the Excursions because the PCM families are different between the trucks and the Excursions. If DJ (Soutthpaw) sees this, he may have some insight because he is using the PMT1 equivalent in his Ex.

gabeyd · #3 Thu, August 13th, 2009, 10:00 PM

Thanks. I think I had PMT1 shifting on my old chip for my Ex before I switched to PHP. So I know what I'm missing in shifting.

The engine is much smoother, and less smoke with the PHP, so I like my engine tuning better, but so far, I like my shifting (or really Torque Converter lock) less than on my old chip.

***Jackpine*** · #4 Thu, August 13th, 2009, 11:21 PM

gabeyd - I drive a gasser, and have the same hangup you do on the way the Torque Converter functions.

I want everything to work more like a manual transmission! If I let off on the gas, I expect the engine to start slowing things down. If I push in on the clutch pedal, I want everything to "freewheel".

But, we don't have those inputs in the automatics, do we? Given the way things are designed, I doubt if we'll ever get what we want.

And, thinking about how things work, it's probably an impossible design criteria.

- Jack

gabeyd · #5 Thu, August 13th, 2009, 11:54 PM

Ya, I do with I had a manual, but they don't make them for the Excursion, and I'm not going to undertake a swap.

But my previous chip left the TC locked until you got below 30 or so, no matter what happened with the brake. It works better for me, especially when towing...

We'll see what Bill says.

Sburn · #6 Fri, August 14th, 2009, 01:15 AM

Interesting subject. Like Jack, I drive a gasser, so it's not always apples-to-apples with the diesel rigs.

But on the subject of T/C locking/unlocking, I was going though the transmission part of the factory service manual (2007 F150) one day. Ford's own transmission road test procedure suggests that the T/C should stay locked when letting off the gas above ~40MPH and unlocking only when the brakes are applied. But my truck has never done this, either when stock or w/ Gryphon. Letting off the gas unlocks the T/C, brakes or not.

From what I've read here and other places, it doesn't sound like anybody's 2004+ F150 stays locked when tipping out of the gas. So who knows what Ford was thinking...

***cleatus12r*** · #7 Fri, August 14th, 2009, 08:33 AM

The concern here is Ford. There are SO FREAKIN' MANY different strategies that do so many different things that it will make your head spin

.

Here is a list of a few different things Ford did with their diesel trucks concerning shift strategies. Some were this way, others were not.

1. No lockup in 2nd gear no matter what accelerator input or road speed.
2. No lockup in 3rd gear until 45-50 MPH. Though by that time, it was in 4th gear under normal driving conditions anyway.
3. TCC unlock when accelerator pedal released. Relock when back into it.
4. TCC unlock with brake input. Relock when brake released.
5. TCC remain locked during either of the above conditions.
6. TCC unlock for 2.5-3 seconds during 4-3 downshift.
7. None of the above.

The shift/TCC strategy that gabeyd is referring to will apply the torque converter clutch on acceleration around 35-40 MPH. After that, it remains locked (or unlocks/relocks so fast that it's not perceived as an unlock/relock event) at any speed above 30 MPH...even on decel from 4th to 3rd at around 40 MPH. This strategy works well for most people and is essentially how PMT1 works right out of the gate. There are a lot of modifications that can be made to make it work even better.....but the base program is what makes the difference. However, I am pretty sure that PMT1 doesn't have the ability to run a glow plug control module like the Excursions have.

I want to say that DJ (soutthpaw) is running the EBM1 calibration in his Ex but Bill would know for sure.

***Jackpine*** · #8 Fri, August 14th, 2009, 10:22 AM

Quote:

Originally Posted by Sburn

Interesting subject. Like Jack, I drive a gasser, so it's not always apples-to-apples with the diesel rigs.

But on the subject of T/C locking/unlocking, I was going though the transmission part of the factory service manual (2007 F150) one day. Ford's own transmission road test procedure suggests that the T/C should stay locked when letting off the gas above ~40MPH and unlocking only when the brakes are applied. But my truck has never done this, either when stock or w/ Gryphon. Letting off the gas unlocks the T/C, brakes or not.

From what I've read here and other places, it doesn't sound like anybody's 2004+ F150 stays locked when tipping out of the gas. So who knows what Ford was thinking...

Not trying to hijack this thread, but Sburn, have you noticed that the TC will remain locked when you're coasting downhill with the cruise control on? (At least mine does). So it attempts to hold the speed in this situation. Tap the brake (releasing the cruise control) and the TC immediately unlocks.

Wonder if the diesel strategy is the same?

- Jack

Sburn · #9 Fri, August 14th, 2009, 10:51 AM

Quote:

Originally Posted by JackandJanet

Not trying to hijack this thread, but Sburn, have you noticed that the TC will remain locked when you're coasting downhill with the cruise control on? (At least mine does). So it attempts to hold the speed in this situation. Tap the brake (releasing the cruise control) and the TC immediately unlocks.

Wonder if the diesel strategy is the same?

- Jack

Jack, that's exactly what happens in cruise.

Other thing I've noticed it that, under certain conditions, the trans will go from 4th unlocked to 3rd locked instead of the more usual 4th unlocked -> 3rd unlocked. Condition seems to be: long uphill, no cruise, 50+ MPH. Key thing might be time under a certain load. It does not behave that way on my daily commute going up the same percentage grade on a somewhat short grade. But out on the Interstate, where that percentage grade might go on for miles, it will do the 4th-U - > 3rd-L shift. Some flavor of TFT control, perhaps?

As for thread hijacking, I get the impression that Cody knows his transmission stuff cold ans seems happy enough to talk about it with us.

gabeyd · #10 Fri, August 14th, 2009, 11:11 AM

Quote:

Originally Posted by cleatus12r

I want to say that DJ (soutthpaw) is running the EBM1 calibration in his Ex but Bill would know for sure.

Maybe that's what my old chip had, I don't know. I don't really know them by the calibrations, I just know that everyone talks about PMT1, and that it leaves the torque converter locked much more. That's what I want... Don't really care if it's actually PMT1, or some other calibration that shifts similar or the same. I know that the shift strategy that I have on my new PHP chip is very similar to my stock strategy as far as TC lock goes, and I know I don't like that...