1999 Ford F800, 5.9L 24V Cummins, Allison AT545.
Anyone know if there a way to "bypass" or is there a fix to the engine being limited to 1500 RPM until the engine/transmission senses that I'm moving? While fully loaded, I'm having trouble climbing embankments such as driveways or RR crossing unless I'm already rolling. The 1500 RPM is barely above the stall speed of the torque converter. Once the truck is rolling, I get full power and all is good. I'm assuming this is normal as it's been like this since I got the truck about 3 weeks ago.


1999 F800, 5.9L 24V Cummins, Allison AT545 auto, 14' dump w/ fold down sides, 16T scissor lift.

 

What brakes do you have? Yellow **** on the dash for the parking brake?

 

Hydraulic, disk front, drum rear. And yes.

 

the electronic engines are programmed that way. a good independent truck/ diesel shop should be able to go in there & change some parameters.

 

Thanks, I have a friend that owns a diesel shop, I'll ask him.

 

OK, sounds like Lucas Girling brakes. Expensive, but good brakes.

Your difficulty is after you have come to a full stop while driving, not when you take off after parking?

I had parking brakes hang up on some Freightliner MT45/55 trucks at work. But that was after being parking and the parking brake set.

Thinking about it, this is probably not your issue.

But as far as how much the engine will rev when it's up against the converter, I don't see how you get more revs than the stall speed.

 

That is correct, after coming to a full stop, the computer/ecm or whatever it's called won't allow the engine to rev past 1500 rpm, just like when it's in neutral, I can hold the throttle to the floor and it will only rev to 1500. The torque converter isn't what's limiting the RPM and I have to roll a good 5 - 10 feet (I haven't measured) before I get full power.

 

Let me know if this link doesn't work, but it shows me taking off after being loaded. It takes a few seconds for me to get rolling and only then will I get full throttle.

Limited Throttle From Stop

 

Not the same as the sticking brake, and not like the MT trucks with Cummins/Allison combos. Beats me.