Electronic Accelerator Pedal Adustments?

[rdownward]

Does anybody know if/how adjustments can be made to the Cummings electronic accelerator pedal? It seems to me that I can't get full throttle even when my foot is pushing the pedal through the floorboards! Also, is there a way to adjust the shift points on the Allison 6 speed? As long as I am running in cruise control, the transmission shifts up and down as it should. But, if I'm running using the accelerator pedal, I have to jam the pedal to the floor to get it to shift from 6th into 5th gear. It also seems to me to shift out of 1st, 2nd, & 3rd too early to get full power from the engine when accelerating from a dead stop. Any thoughts or instructions on how to make adjustments would be appreciated.

[gfs1943]

Are you running in Economy mode? That mode, I believe, is designed to keep the transmission in as high a gear as possible. Try the Mode button, to see if it makes a difference. But I don't see how that would be affected by using cruise.

[Phil R]

Maybe this link will help.
http://www.cruisecontrolking.com/images/2600-M_2.PDF

[Skip426]

No adjustments on the pedal, a tech can test for a full throttle reading with a scan tool, trans shift pattern is adaptive to a degree, Allison shop could tell you what programs (changes) are available to the shifting pattern. Most shifts would be set to engine torque RPM rather than horse power RPM, as upshifting to keep the engine in the torque power band provides the best fuel economy/acceleration.

[Algoma]

Ignore the comment about the cruise king control, that is for pre-electonic engines. All shifting is determined by the Allison ECU and that programming can be changed by an Allison dealer. Remember that these diesel pushers are programmed for maximum torque not maximum power so they will appear to shift up earlier than you would expect on a gas engine.

[rdownward]

Thanks for your comments everybody. I've had 2 pushers previously and never felt this frustration level with the feeling of lack of acceleration, downshifting on demand and early shifting through the gears. And, no, I don't use the economy mode on the Allison. Looks like I'm off to the Diesel shop for an analysis.

[bluepill]

Don't know what divetrain you have, but in mine (see sig line) the "governed speed" is 2600 rpm, and full throttle upshifts occur there as per design. The torque curve of my particular ISB shows max torque of 750 ft. lbs. from 1600-2600 rpm, so that makes sense. If you can get the specs on your motor, you can check to see if you reach governed speed at full throttle. If not, it's possible that one of your sensors is out of range, and the ecm is defaulting to a modified lower power map as a safety strategy.

[daveshan]

Please post up what you find out.

I also thought the shift points on my 330hp 36SDS were way too soon and that downshifts were hard to force.

I just attributed my unease with the shift points to the fact that I came from driving a Power Stroke with a 4000+ redline that would shift at well over 3500 rpm under heavy acceleration when loaded.

The thing sure drives/climbs well so maybe it's normal.

[Skip426]

Does the engine ever pull to governed RPM ? Possible fuel supply, filters, poor lift pump ?
Usually these type of problems will cause delayed up shift, but if you're having it tested out , be sure they test every thing . Even an air filter , turbo boost, the whole 9 yards.

[EngineerMike]

Roger's description sounds like a serious drivability problem. Dave's description sound like coach is driving normal. W/known good drive trains, I've never spoken to an ISC owner who thought they didn't have enough power to keep up w/trucks, nor an ISL owner who thought he/she was shy on power; if yours feels in that ballpark then its likely w/in spec, but if like Roger's then likely a problem that'll feel real good when its fixed.

Of course I never met a boy who didn't want more horsies under the hood, but that's a different problem.

[daveshan]

Mike, It moves along very well, pulled up the westbound (easy) side of Wolf Creek Pass with the curves being the limiting factor for speed, and it will definitely run with/pass the big rigs both flat and on hills.

It just doesn't do what I "think" it should do sometimes. I just chalk that up to my 5 years of driving a high reving diesel small block with a variable vane trubo.

The SilverLeaf shows it getting to (and staying at) the full 950 ft/lbs of torque when needed.
Thanks for the input.
Dave

[rdownward]

Hello again guys. Forgot to mention in my earlier posts that I have the ISC engine. Just another comment or two. I can get the engine to pull easily to full governed RPMs by manually shifting into lower gears. All filters are new and the engine seems to be operating just fine. The problem I am having just seems to be with the shift points that are programmed into the transmission or that the accelerator pedal position and the transmission aren't communicating properly somehow. But, what I don't understand is that when I am operating in cruise control, as soon as there is some "drag" on the engine, it readily shifts down. But, when operating manually with the accelerator pedal, unless I stick it clear to the floorboards, it won't shift down. It almost seems like the electronic accelerator pedal mechanism just isn't doing what it is supposed to. Anyway, it will probably be a while before I herd it on down to the diesel shop to get it checked out. But, when I do, I will definitely post the results. Thanks again for everybody's input. Much appreciated.