Greetings from a new member, one with a question. I have a 1997 Dodge with a Cummins (of course), strictly stock, 5 speed, 145,000 miles. After four years of driving it with no smoke, much power and great mileage it began losing power and mileage last fall, so I took it to a local diesel shop where it was tuned up - valves set, wastegate set, timing checked, lift pump checked, etc. That helped some, but it ran different. Instead of the turbo coming in at 1900 rpm and pulling hard to 3000, there was now a strong pull from 2000 to 2500, then nothing, and a puff of black smoke when the accelerator was first stepped on. Things kept getting worse, my last trip to visit the kids mileage had dropped from 20-21 down to 14, and there was no power. It felt like someone had stuffed a potato in the exhaust pipe (I looked. No potato). While visiting the kids I took the truck to a shop specializing in diesels (mainly big rigs). The mechanic listened to my story, looked under the hood, disconnected the line from the intake manifold to the wastegate control, blew on it and told me the diaphram was shot. He blocked the line from the intake manifold, said it would hurt nothing to run the truck that way unless I was pulling a load and sent me down the road. Hoo-hah! Power! Mileage back to 20! And now, a few weeks later, huge clouds of black smoke anytime I shift until the engine hits 1600 rpm or so. A very, very, soft touch on the pedal minimizes the smoke, but doesn't eliminate it. I would ask the mechanic that worked on my pickup originally just what he did to it, but he's no longer here. I would talk to the mechanic that disconnected things, but he's 360 miles away. Does anyone have an idea of what might be going on? I'd appreciate any input.

Thanks.

DRam11

 

Adjust the star wheel and you'll be golden!!

 

not...

replace the AFC spring and replace the diaphragm and hook the boost line back up and you'll be golden

 

You could have a turbo going bad on you. Without any boost the cummins is a real pig and just smokes when you push on the peddle. You might pull the intake hose off and wiggle the shaft side to side and up and down for play. Also look to see if the wheel has been hitting the housing. Might also be such a thing as a bad injector too. Good luck!

 

I was only a few sentences into your post before I figured your AFC diaphragm had a hole in it.
Sounds like your mechanic was good at diagnosing the problem but not good at fixing it.
Far as I know there is no way to fix it by blocking the line as he did.
The diaphragm is very cheap and easy to replace.

 

Thanks everyone. You've given me places to start, with replacing the AFC first. I'll update when done and let you all know what I find.