Question for the Mad Dr.

[orygunf150]

Originally Posted by Power Hungry

That's exactly what it's doing and I do know where the map is. The problem is that when we change it to improve the range, it often (read that as nearly always) sets a Throttle Control DTC. That's what I'm trying to work around.

Thanks for looking into it Bill, let us know if you find anything out.

Jack... maybe the power is there in the upper rpm range allowing you to pull the hills, and the power reduction happens in the lower rpm range which is where you would be in a slippery condition. Just a thought. It seems as though Ford would have made this feature optional, (it's there if you need it).

[Jackpine]

Originally Posted by orygunf150

1st and 2nd gear positions cause the PCM to remap the throttle
essentially the throttle gets cut in 1/2 by placing the shift lever into 1st or 2nd. the throttle then is more "sensitive" and you have better control of the wheels.
this is achieved because you now have full pedal travel to control only 50% of your normal throttle...so you don't inadvertently spin the tires by giving it too much gas
it's a little known feature to help you control low speed situations. like boat ramps, towing heavy loads, 4x4 offroad

This is a response from Tylus on the FTE forum regarding the same issue, if it is the pcm remapping the throttle I would think it could be programmed to not do it. Or, perhaps there is a microswitch somewhere that can be bypassed. What do you think Bill?

Shouldn't this be "less sensitive"? (But I'm not trying to split hairs here, just trying to understand this). Effectively then, placing the shifter in 2nd (or even 1st) DOES make the truck less likely to spin tires on startup in a slippery situation.

But now, I've got another problem. From Tylus' explanation, it would seem that you are very limited in total power output if you have locked the transmission in 2nd. As I said in a previous post, that doesn't seem to be my experience, at least not when I'm towing my trailer up a 7% grade in the Colorado Rockies and passing every other RV and semi in sight (since I can maintain 65 mph and they can't). I lock it in 2nd to keep it from shifting back and forth between 2nd and 3rd in this situation which it will do on grades like this. This technique even seems to work on very "twisty" steep roads where the maximum speed is about 25 mph. I have no problem whatsoever getting everything moving from dead slow (around a severe switchback) while in 2nd gear. On shallower grades, of course, I can just lock the overdrive out to keep from cycling between 3rd and 4th.

I guess what I'm trying to ask in all this is: If my total throttle input is cut in half, where the heck am I getting all this power from? Is it Bill's fabulous tune?

- Jack

[Jackpine]

I've thought about this some more, and maybe it works like this?

If we assume the change in Throttle Position (TP) vs Pedal Position (PP) is nearly 1:1 (linear) when the gearshift is in Drive, then possibly the change in TP vs PP is more parabolic with the shifter in 2nd or 1st? In other words, possibly TP reaches the same maximum point in the lower gears, but it does it more slowly at first?

Thinking about it, that's the way I would have designed the relationship, because there's no reason I can think of to limit the max TP.

(And I know the Drive TP vs PP doesn't have to be linear, I just used that as a base for comparison).

- Jack