duramax low power

[chagburg]

I have 2002 k2500 crewcab allison duramax. I thought the power when towing was not good. The dealer said everything was within specs so I put it on a dyno. They told me they could test hp but they couldn't test rpm and torque because they get that from the spark plugs. It showed 170 hp at rear wheels. Complained to GM and they say they can't accept any test that doesn't come from a GM dealer, and there is no GM dealer in the southeast equipped to do a hp or torque test. Anybody had any similar circumstances or can offer advice?

[mackin]

Welcome first off.....


All right I'll start .....

170 HP is mighty low.....Most dyno at 245 at the rear wheels...Could just be wasn't done properly, not by fault, but improper equipment....This is the third post I've seen on this subject on two forums (Gm-Diesel) on this.....

How many miles?
What were you towing (weight)?
What are you comparing it to (have you towed similar weight with a different truck)?

You have to give some more info to stir up some interest.....Hopefully you'll get some simple solutions.....If there available...

MAC

[chagburg]

I have 2700 miles on the truck. It seems no more powerful than the 97 6.5 turbo diesel I traded in for it. I was towing a 16' gooseneck trailer with one horse, <6000lb. and could not maintain speed up a decent grade.

[Paintdude]

I would recommend driving another Duramax or Dyno another Duramax on that dyno to compare before I would loose any sleep over a dyno operators numbers(if the two truck are close to the same the numbers dont matter or are incorrect)...The difference is just to great for you to get those kind of numbers..

Plus is the Duramax rated at the rear wheels or the crankshaft? My guess is GM rates it at the crankshaft..That is almost 10% more right there if not more as compared to Hp at the rear wheels..

Just my 2 cents..

[ 11-11-2002: Message edited by: Paintdude ]</p>

[chagburg]

GM does rate hp at the flywheel, but they claim 300hp and I only got 170hp, thats 43% less.

[Maverick]

I would say 170 is very low. At the 02' Rendevous my 3500 put down 258 rwhp and 477 lbft. I would do what Paintdude said and run another Dmax. Check to see if the airbox is plugged. Maybe that aluminum foil on the fender deal.

[1822]

My 2002 3500 acted the very same way, very unimpressive when new. I thought my 98 6.5 had more power. As the miles accumulated the power also increased to the point of being awsome at 6000 miles. Tow a 14,000 lb. 5th wheel and hills my 6.5 went up at 40 mph this truck does at 65 mph. There must be a break-in program in the computer because the dealers mechanic told me this is what was going to happen when I complained to him.

[Amianthus]

Not being broken in may be part of your problem (there are differing opinions on this). But that aside, you are running quite low. I usually guesstimate around 20% driveline loss for an automatic. The numbers seem to work out pretty good from there when I run on a dyno (results may vary). However, you are still way off. What I would do is find another Dmax owner near you and go for a ride in his truck. See how it performs and behaves. This will give you a better idea of what your truck is lacking. I don't think that if you found someone from this page, that they would refuse you a test drive (ride). But I don't want to volunteer other people's trucks.
I would keep on GM about this. Find other dealers to look into it. Complain to MA' GM. Any way you slice it, you paid a ton of money for your truck and GM should deliver what you paid for.

[DieselDennis]

170 HP is low for these trucks anywhere you measure it. I agree about driving another truck. Just ask a salesman for a test drive and see if they feel the same.

Good luck with any dealer if they can't dyno the truck and it won't set any fault codes. See if they can hook up a scan tool that will measure instant HP. See what it reads.

[chagburg]

Thank's for all the suggestions. I'll try driving another duramax. The only thing is, it doesn't matter how much I convince myself the power is low, the dealer says nothing is wrong, and GM won't accept the word of anyone else.

[Amianthus]

Tell you what. Bring in a copy of SoMnDmax's dyno sheet and your dyno sheet and tell them that his truck is bone stock and that your truck should produce as much power. Or at least within 10%. :D

[trailrider0493]

A friend of mine has also complained of this same problem. He has a 2002 GMC D/A Crew Cab dooley. He has a Lance slide-in camper and pulls a 2 horse trailker behind it. When we went to MO this fall trailriding, he said it ran pretty sad. He drove another guy's GMC D/A while we were there and he said there was no comparison! His was really sick. His dealer told him that every thing was "within specs". Don't know what has happened in the last month. Any help or advice I can pass along to him will be helpful.