'01 2500HD/Allison Limp while towing

[TripleG]

I have an 2001 Dmax,Allison with 174k. I, as many have had injectors replaced over the years. In recent months when i pull my 5th wheel (11,000 -12k) it will go limp. I can be traveling at say 65mph and then ill get an SES light the tach goes down gradually and will eventually be at the point where im basically idiling. I lose next to all power to the point i have to pull over. I cut the truck off and let it set for a few seconds and cut it back on. When back on the SES is still on but i do have power restored. It will go about another 5-15 miles and it will do this again and again and again. When codes are pulled nothing showes up at all. I have very minimal mods done. CAI and hypertech. Other than that the engine is stock. I wanted to get an idea of what the cause could be before i get that dreaded call from the dealer. My gutt says its the injectors. My dealer tells me the injectors are covered by Chevy thru 200k. Oh, when i unhook the 5th its back to normal like ive driving a 6000 lb corvette. So what gives on this...??

Any thoughts or comment are greatly welcomed.

[Mark Rinker]

First of all - welcome aboard! By searching the forums you'll find lots of information to help troubleshoot this problem.

If you are seeing the SES light, there should be a code available. If your programmer isn't reading it, get to a service shop and have them use a scan tool to pull codes.

Questions: When the towing limp happens, are you running the stock tune, or the Hypertech tune? If with the Hypertech tune, what level are you running while towing? Have you ever experienced the limp in stock form?

My first guess is that you are getting an overboost code that is inherent to the 2001 programming. Some dealers will update your ECM to the 2002 programming, usually for a fee. This will get rid of that problem.

[TripleG]

thanks and im happy to be here and part of the board :)

Ive had the issue in and out of Hypertech. The one common factor is that is seems to happen mainly when traveling up hill. Not as in only on a hill but like when traveling say from Atlanta GA to Greenville SC. On a recent trip there it happened on the way there but not on the way back. With the issues at hand ive mainly been towing in stock programming so to eliminate the hypertech module. From reading many posts here on similar issues it appears that the fix may be found in re-programming with the 2002 programing over the 2001 which im sure is what is in my truck.

I hate to spend un-necessary moneys when i can save those for important things like more power, shocks and such :)

[JohnC]

Not as in only on a hill but like when traveling say from Atlanta GA to Greenville SC. On a recent trip there it happened on the way there but not on the way back.



Try turning the compass in the mirror off if you have one and holding your map upside down...

[Mark Rinker]

One way to spend some money, but get the 2002 programming AND a switchable tow/performance tune is to swap out your ECM for a reflashed Kennedy.

Check it out at www.kennedydiesel.com (http://www.kennedydiesel.com)

My towing mileage went up signficantly, along with less soot in the oil. It appears to be a better tune that comes stock on the LB7s from the factory.

[TripleG]

so am i correct in that the Dealer is the only one that can put in the 2002 programing?

[Mark Rinker]

Some dealers won't do it - not sure why. Mine did.

I think John Kennedy can set you up with just the 2002 programming, if thats all you require. Call him to verify that.

[TripleG]

sounds good...ill contact kennedy and see what the best way to go is. :)

[NutNbutGMC]

so am i correct in that the Dealer is the only one that can put in the 2002 programing?What dealer in Knoxville is working on your machine? I'm in Kingston and was just curious.

[TripleG]

What dealer in Knoxville is working on your machine? I'm in Kingston and was just curious.

i just moved to knox from atlanta so i dont have a dealer here.

[NutNbutGMC]

i just moved to knox from atlanta so i dont have a dealer here.

I have found none in Knoxville that are reliable with diesel service (is why I was asking). There is one good diesel wrencher that was in my hometown at a dealership) and went to work for the Mercedes place in Knoxville.