--------------------------------------------------------------------------------

My 2002 Duramax with 81K miles is running Banks exhaust and K&N air filter. It has a puff of black smoke at start up. Idle exhause appears clean. At any speed an increase in throtle causes black smoke until reaching speed. A heavy load causes worse smoke. I have cleaned the air filter, MAS, and replaced the fuel filter.

I use 4 oz Diesel Kleen with each fill up.

For $95 the dealer told me there were no codes and all pressures were good. A few day before the trip to the dealer, the check engine oil lite came on.... The level was OK

Thanks for any help.

Jim

 

they will smoke until boost catches up. In other words, you're cruising at 45 mph and go to pass a guy; depending on how hard you step on the pedal it is normal to puff black smoke as the fuel gets put in but the engine isn't up in boost yet, so it's a lot of fuel, not a lot of air. As soon as the boost jumps it cleans out. You should be able to do normal accelerating without smoke though if the tune is right. If it smokes at any acceleration it sounds like an air issue, and since you mentioned that you had the K&N filter, I'd take a good look at the maf sensor and see if it has oil on it. They have that issue a lot with those filters, or any filter that has too much oil on it, and once the oil film gets on the maf it throws all the air calcs off a ton. Try cleaning the maf with spray on brake cleaner or similar, and maybe stick a stock filter in place of the K&N, or at least clean it completely, and don't oil it just for a test.

Shouldn't puff smoke on a start though. I tried a tune once that did that; he had increased the timing at idle, and it would kinda kick back as it fired up, and you'd get a puff of smoke when it started. Once I took the timing back down it never did it again.

 

Thanks for the input, I will spray the sensor with carb cleaner.

Jim

 

Cleaned the MAS with carb cleaner, may be a slight inprovement..... Is the MAS a go/no go situation? Can it be "off"

Thanks again.

Jim

 

I would expect the truck to throw a code if there is a problem with the MAF, or any other sensors that would cause this problem acutally. Hopefully some more diesel guys will chime in.

 

Are you a member at dieselplace? They know their stuff over there.

 

70+ folks have read the post, no one has waded in yet. The tech at the dealer also suggested I spray the MAS. Driving me nuts.

 

well, they probably don't know what's wrong with your truck............. I've never heard of your problems with the stock tune (I assume this has no tuner in it, you didn't mention one). There have been numerous oily maf issues with aftermarket oil treated air filters.

If it was my truck I'd swap the stock air intake back on (there are problems with some of the air inlet systems out there disrupting the air across the maf and causing all kinds of issues), disconnect the battery for 15 minutes to half an hour, then hook it back up and see how it runs.

Jody

 

I would try cleaning it again, but use a different cleaner they have a spray that you use on the maf . I think carb cleaner leaves a oil film behind...

 

How do the terminals in the connector on the MAF look? Maybe you could try cleaning those also.