Black & White smoke and a knock?
 

In addition to the GMC I have a 07 classic 2500HD Duramax.

Today I had to get on it to pass and I got a huge could of black smoke that turned white when I got off the gas and it included what I would describe as a ping if it was a gas rig whit low octane gas.

No codes and at cruse no problems but it is also smoking at moderate acceleration also, just not as bad and no white or ping.

I checked the air filter it is clean and the gauge is at the bottom of the green zone where I would expect it with a new/clean filter.

No mods done to the engine except to open the air box and remove the cat and that was about 8K ago. Has 48K on it.

Any suggestions at to what it might be?

Re: Black & White smoke and a knock?
 

Whens the last time you changed the fuel filter? That's the first place to start.

Re: Black & White smoke and a knock?
 

Okay? I am a bit puzzled here though. How could an old filter cause it to dump big loads of fuel into the motor? I don't profess to know that much about diesels but it seams contrary to the nature of physics that a restricted (old and dirty) filter could flow more fuel.

Re: Black & White smoke and a knock?
 

Check for boost leaks, Do you have a boost gauge? Have you had a scan tool put on it? Just because theres no check engine light does not mean that theres no stored codes.

Does the truck run good?

Hate to say this but it might be a cracked injector body.

Re: Black & White smoke and a knock?
 

I did put a scan reader on and nothing.
It does run well.

I gave up and took it to the dealer today. $236 later all they could find was cloudy fuel. All the injectors everything checked out good. Put a new filter on it and still the same problem. Well the dealer said to run two clean tanks of fuel through it and if it is still doing the same thing bring it back. I got about 25 miles away when I was passing a truck on a hill in a passing lane. It was smoking but I stayed off the gas enough that it didn't let it knock when the check engine light came on and the power dropped off.

It is back at the dealer and they can keep it until it is fixed right.

Re: Black & White smoke and a knock?
 

If you have contaminated fuel the last thing you want to do is drive it out on a HPCR injected diesel. The tank needs to be drained & flushed. Then hope for the best because a dealer will not warranty injectors when you have contaminated fuel.

Re: Black & White smoke and a knock?
 

The black smoke is normal when you roll into it to pass. Particularly since you've removed the cat, they have a tendency to trap some of it.

The white smoke when getting off of it is cause for concern. What kind of RPMs were you turning to pass the person? The LBZ Duramaxes (3rd gen, 06 & 07 Classic) are hands down the best Duramax to date. They've got a lot of improvements over previous generations without most of the newer emissions devices. My roommate is from Poulsbo, he says take it to Jet Chevrolet, not Grey (they are hit & miss). Both of us actually have 2007 Classic Duramax equipped trucks.

Re: Black & White smoke and a knock?
 

This was not just a little smoke it was a HUGE cloud of smoke. The kind that would blot out the sun!

I was turning about 3K when the code kicked in. I was staying off it enough to keep it from pinging. The white smoke would come when I got off the gas and it dumped fuel into a cylinder that should have been at rest.

I work in Pt Angeles and have developed a good relationship with the GMC dealer Ruddell in town. We take all the work rigs to them regardless of make for service and repair.

When I checked in tonight they were still working trying to find a bad injector. The code said a low pressure on on rail but they were having a hard time detecting what injector was bad.

Re: Black & White smoke and a knock?
 

BINGO! You win the lady a stuffed giant Panda.

It took the dealer 2 1/2 days to find the bad injector. On the bench they all tested out good but when put back in and run up a hill it would throw a code for bad injector. He had to test them one at a time on the road with some kind of rig that required him to remove a bunch of stuff, hook the test rig up to an injector but the stuff back on and go run up a hill. Not only that but he had to test all 8 that way to find what one was different from the rest.

Now we are waiting for a new injector.

I had purchased the extended warranty when I git this truck 8 months ago and it has now paid off. $100 deductible is all in on the hook for.

Re: Black & White smoke and a knock?
 

Thats good news on the cheap injector replacment:uhmk:.

Change your oil & filter, the bad injector was dumping fuel in the crankcase.