Why does truck run stronger after a tow?

[Billy14]

Hey guys & girls,

Upgraded to the Hot Juice a few weeks ago. I pull 16,000 lbs. level 2 tow/haul & run the truck normal in level 4. I only pull the load one or two times a month.

What I have noticed is after a tow (5 miles or 150, makes no difference) the truck runs out MUCH stronger for a few days & then slowly sinks back to what I would call normal. Edge thinks its the shift points but I don't agree at this point. You can feel it in the pedal through all the gears. Its like going from level 2 to 4. Really noticeable. I'm thinking that the ECM has learned to dump a lot more fuel to get the load moving & then it takes a few days to fuel down without the load, & back to normal driving.

Any ideas,

Billy

[ 01-29-2003: Message edited by: Billy14 ]</p>

[Dave_WB3FYV]

What's your fuel mileage like? Does it go up corresponding to the perceived drop in power??

If you're like me, the truck 'feels' much more lively after unhooking 11,000 pounds, but that's after a day or two and is just my seat-of-the-pants. Hard to keep my foot out of it for a while :D

[afp]

Billy,

That's easy. Our TCM is always learning. I personally do not like that feature. Anyway, the truck "learns" how you are driving it and adapts. I usually drive reasonably conservatively. When I do hit it hard--like launch from a stop WOT--it doesn't do it's best on that first run. It takes two or three before the truck "learns" to limit defueling and shift at the proper time to allow max acceleration.

When towing you dozer, your truck is close to max performing than when you drive it empty, the trucks adapts to the higher demand, and you reap the benefits of that "new learning" for a while.

I hope the tranny upgrades that are offered include a software feature that keeps the tranny consistent.

Blaine

[schnier]

I think it is from cleaning out the motor from unwanted, excessive carbon and dirt build up. All my old gas, and new diesel trucks have run better after a tow, on Monday morning. They seem to jump out, shift better and feel all around stronger. Drive it like you stole it. Is it computer related or not, I can not answer that.

[chrisinkanata]

I must say that I have noticed the stronger post tow performance as well. With the gasoline engines I have I have attributed it to 'cleaning the cylinders out' but I doubt that's the case with the duramax. I have to go with the adaptive learning of the ECM.

I also have observed that it does not even take a heavy tow to replicate this perceived increase in performance. I have to drive from Ottawa to west Toronto every Sat and back, about a 600mi round trip. These are easy trips at 110km/h or so. No big accelerations,loads or anything. Monday and Tuesday that truck runs like a top. Seems to get a bit sluggish towards the weeks end.

Gotta love it though....26mpg with less expensive fuel. My wifes van that weighs half as much is had pressed to get that kind of mileage.

[NutNbutGMC]

^... 26 mpg all you getting? Mine is getting 28.5 mpg..... :rolleyes: :rolleyes: :rolleyes:

[DMAX4LIFE]

But that's probably because those d@mn mini-vans are always passing us at over 100 mph right..lol :D :D

[Silver Bullet]

Billy,
I agree with afp. And it would be nice to have a "dumb" tranny sometimes!!! I guess that would be a ZF-6!!! D'OH!!! :eek: :D

Steve