torque converter - Q

[Dfishrmn]

Originally Posted by JackandJanet

I don't think it has anything to do with shift firmness, Dfish. I bet it's because you had the cruise control set, which lets up on the throttle as you start down the incline. If the converter is locked and you release the throttle, it will unlock and, Bill explained that was a feature Ford put in to increase your fuel economy. (The engine/transmission doesn't drag in coast). Now, I'm guessing that the small decline wasn't really enough to keep the throttle at the "let off" point that caused the unlock, so, it locked back up again. But that wasn't stable either, so it unlocked/locked....

Possibly, if you reduced the lock and unlock speeds for each upshift/downshift, it might "tame" this behavior a bit.

- Jack

Yeah, I didn't think it had anything to do with the firmness, just a coincidence. You described the situation almost perfectly, so that could explain the lock unlock action. I did back off the 4th gear lock point one degree. We'll see how that works!

[Jackpine]

It's not a degree in these settings, it's speed, in mph. Which, is kind of misleading too, since shift and torque lock/unlock depend on not only speed, but throttle position too. I suspect you're going to have to move the setting quite a bit more to notice much of a difference.

- Jack

[Sburn]

Originally Posted by JackandJanet

It's not a degree in these settings, it's speed, in mph. Which, is kind of misleading too, since shift and torque lock/unlock depend on not only speed, but throttle position too. I suspect you're going to have to move the setting quite a bit more to notice much of a difference.

- Jack

I've wondered about the same thing. Yes, the shift point are mapped against the throttle position, but is there another factor (axis) on the map? Maybe load % and throttle position both govern shift points...

Likewise, I've wondered about the definition of WOT. Does the PCM go into WOT map at a specific percentage of throttle pedal position, a specific amount or rate of change in TP position, or does WOT kick in when the pedal really hits the metal...

[Jackpine]

I think, but again I could be wrong, that the balance between speed and throttle position determine the "load". If you are say, cruising at 40 mph, there is little load, but if you advance the pedal (try to accelerate the vehicle), then the load increases. It's controlled by a valve, I believe which "floats" back and forth in response to both speed and pedal position, but, below a certain speed, regardless of pedal position, a downshift is commanded and, above a certain speed, regardless of pedal an upshift is commanded.

But, as I understand it also, a WOT throttle overrides everything and shifting becomes controlled totally by RPM.

As far as what constitutes WOT, I don't know. It seems to be awfully close to the max deflection point though. I know if I let up just slightly in a WOT situation, the transmission downshifts. I'm sure someone on this forum can enlighten us (and probably tell us that all my earlier statements were wrong too).

- Jack

[Grabber523]

WOT throttle is usually anything over 80%, regardless of load or how fast the "pedal hits the metal" (I like that...LOL!!). This is the point that the ECU goes into "open-loop" and reverts to the basic programming...start-up, cold-running, and WOT. Basically the stuff you can adjust on any handheld tuner. Once the ECU senses that the engine is warm (closed-loop), it uses all the emissions sensors to adjust long and short fuel trims and to maintain efficeint operation. You are right that WOT overrides everything, because it "locks out" the sensor information and looks specifically at the predetermined tune values. That's why if you were to say, adjust your spark advance when it is 30* ambient and dry and it works great, at 70* with high humidity, it will not run the same at WOT, possibly to the point of causing damage. The ECU no longer cares about what the air conditions are, it goes to the basic programming (for 30* and dry in this example). Part-throttle, it affects nothing because the ECU is in closed-loop, using the info it's getting from the MAF, O2s, etc.

[Jackpine]

Good information Grabber, thanks! This also makes me think it's not a good idea to "continuously" run in WOT (even though I know you really can't). But, people who continuously like to drop the hammer are going to be in that open loop mode probably more than is good for the engine.

- Jack

[Grabber523]

Originally Posted by JackandJanet

Good information Grabber, thanks! This also makes me think it's not a good idea to "continuously" run in WOT (even though I know you really can't). But, people who continuously like to drop the hammer are going to be in that open loop mode probably more than is good for the engine.

- Jack

...and that's where the difference between running a "safe" tune versus one on the verge of detonation comes in. Factory tuning runs a little less timing and a little more fuel at WOT because of the variances in temp, air density, blah, blah...but there is power to be found up there.