Community Forums

Sky_Boss · 08-31-2014, 04:36 PM

Quote:

Originally Posted by Rocky Larson

Chances are you will experiance your first transmission "Limp Mode" on your mountain trip. It can be quite unsettleing if you don't expect it. You will only have enough power to pull over to the side. When the Allison transmission decides it is safe to resume (can be 15 minutes or more) power will be restored. Once experianced your climbing will become less aggressive.

OK...I confess...what causes a limp mode and what is it?

ChasA · 08-31-2014, 07:20 PM

Limp mode??? Maybe it's something to do with the Viagra ads on tv???

Fred and Bonnie · 09-01-2014, 05:11 PM

Quote:

Originally Posted by Gary RVRoamer

Push the go-peddle to the floor and the two will arrange thing to apply the best combination of fuel & air to the engine for max horsepower and the tranny will shift to keep the RPMs in that range while delivering power to the rear wheels. Computer controlled automatics aren't slow to up or down shift like in the old vacuum-controlled days - they immediately react to changes in demand.

That's the reason I manually downshift, I don't need to push the load pedal to the floor.

BTW "Limp Mode" is the power train saying "Don't Destroy Me"

Fred

mgscott4 · 09-01-2014, 07:31 PM

For my 2006 Hurricane 8.1L with Allison 1000 transmission, I keep the RPMs around 3200-3600 while climbing. I will manually shift to whatever gear gets me 3200-3600 and settle in, that is my speed going up this grade. Could be 35 mph or 60 mph, depends on the grade. If I can't hold this RPM, then I manually downshift once it gets to 2200 -2500 rpms, to the next lower gear and get back to 3200-3600 RPMs. I never press the gas pedal to the floor. If the MH is slowing down on the grade at around 3/4 throttle, then I am in the wrong gear for that grade and need to be in a lower gear once the RPMs drop,

I Must be doing something correct, I have 105,000 miles with no engine or tranny problems (Knock on wood).

TexasTom · 09-02-2014, 10:36 AM

Did a fair amount of driving in the Colorado mountains this summer with the same engine. The graph with the torque curve is indeed your best guide to driving and I found it to be right on. Going up steep grades with a loaded coach, I kept it around 3,200-3,400. Sometimes that meant we were not going very fast, but the transmission and engine temps never got high. Going downhill tried to do the same, but on occasion, on steep slopes would let the engine speed get up to 4,000 for braking and again, experienced no problems.