Today was the first time I towed my boat (12,000lbs) up hill. To be honest, I wasn't impressed. From a dead stop, I was unable to get it to exceed 25 mph up a moderate incline. With a slight downhill, into a moderate grade, I was able to get it to 45 mph, then she began to back off to about 40. EGT's never exceeded 1000 and boost was about 16. Is this normal or should I look into getting something fixed? Just doesn't sound right to me. I had comparable performance from my Suburban with a 454!

 

Nope not normal.

You aren't fueling all the way for some reason, you should be fueling harder than that and subsequently making more boost, closer to 20 PSI stock.

Checked all filters, intercooler connections, wastegate operation?

 

Not normal at all, I see in your sig you have 4:10 gears as well. Something just ain't right.

 

Have you checked your air filter? I don't see an aftermarket system in your sig- it may be plugged full of dirt. You should definitely be at more than 16#.
Is there any smoke out of your exhaust? Color?
Mike

 

I had a similar experience when my truck was stock and I'm only towing half the weight you are... I make the same trip frequently with my toy hauler trailer and there were a couple spots where I would have to drop to 2nd gear... the EZ really kicked my truck in the butt though.

Anyway, with my experience, I would expect the results you are getting towing that much weight. IMHO, 12,000 lbs is a lot of weight... even though I know many guys on here are pulling more.

Maybe there was/is something wrong with my truck?

 

Ckeck the simple and cheap stuff first. Have a friend mash the fun peddle with the engine off while you ensure the throttle cable is pulling everything in like it should. If that is normal replace the fuel filter and check lift pump pressure. I agree with the air filter, give it a good eye ball and replace if necessary.

 

You might check you IAT / MAP sensors... I know you don't have jake but it could be the problem. Both of these sensors control fuel rate.

 

Definately NOT normal. Still no posts on the color of your exhaust. That would be helpful to diagnois the problem.

One thing that has not been mentioned yet. If your exhaust is black check your innercooler boots. They have a tendency to slip off and you loose all boost. Seems like the boot closest to the turbo is the main problem. Check it out.

 

To be honest, I didn't notice any smoke, so I would tend to say there wasn't any. Reason I say that is because I was watching the trailer closely, since I haven't towed hills before and there was a distinct smell of brakes on a downhill run.

Fuel filter and pump are new. Showing 14 psi at idle and couldn't pull it down below 12 psi on the hills, so I know the fuel delivery is ok.

I'll be towing the boat back to the storage area on Monday, so I'll take more notice then of the exhaust.

Unloaded, pushing WOT, on these same hills, I can hit 900* and 18 psi boost. I noticed that the truck was in 3rd and accelerated to 45 mph, as it dropped I depressed the accelerator and downshifted. The truck maintained 40 mph at 2500 rpm, but would not increase nor change gear. That's about all the info I can remember from the run, so I hope that helps.

 

Can you check the codes?
Mike

 

Maybe the brake smell you mention was in fact the clutch slipping?

 

He's got an auto Bill. Maybe time for a new torque converter & valve body. You would be surprized at how much more power you can get to the ground with a beefed up tranny.

 

I'm sure a beefed up tranny would be nice, but the one I've got seems to shift just fine. As far as the codes are concerned, it hasn't thrown any. It looks like I'm not going to be towing it again until next weekend. I had the boat at my house to do a rewire, which is going to take a little longer than anticipated. Would an injector problem (clogged) give the same symptoms?

 

Ok, towed the boat back yesterday and this is what I experienced:

When pulling a hill, I got 18 psi boost and 1050* egt. As I began to pull a hill, she'd give a small puff of black smoke when accelerating from a dead stop. On a short pull uphill, she got to 30 mph and held. The road I was driving is not too hilly. If anyone is familiar with Newport Beach, it's the stretch of Jamboree, between University and PCH.

This is not the performance I expected to get from a Cummins. My brother-in-law has a Duramax and has no issues towing ... there must be something wrong!

 

Are you still running the same amount of boost when hauling as empty? If so then,
I would look at the tranny. You say that when you are not hauling everything is fine, and when hauling you don't have much power. I would say that the TC may be slipping and you are not getting the power to the ground. This is if you are running the same boost and such as when you are empty.