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frank, Chevrolet Technician
Category: Chevy
Satisfied Customers: 3420
Experience:  33 years experience,24 years of Chevroler/GM experience and training .ASE Recertified Master Tech,
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2003 Duramax LB7 vehicle emits grey/white smoke..Dealer says..exhaust

Resolved Question:

2003 Duramax LB7 vehicle emits grey/white smoke from tailpipe after extended (5-10 minutes) idle. Dealer says fuel return rate is ok. Also, heavy ammonia/urea smell from exhaust and heavy soot in tailpipe.
Submitted: 7 years ago.
Category: Chevy
Expert:  frank replied 7 years ago.
If your feul return rate is good and the balancing rate is good(the policy on the injectors only covers the return rate)smoke at extended idle is normal and there is a bulletin out on that.Are you running off road or bio-diesel?
Customer: replied 7 years ago.

Minor amounts of offroad and NO biodiesel, but this truck has never in 112k miles smoked like this since i bought it new in 2003. Dealer replaced injectors about 40k miles ago. Truck will emit CLOUDS of smoke, not a wisp...sometimes from stop and go traffic. Truck uses zero oil and coolant level is normal.

Expert:  frank replied 7 years ago.
#1-off road is high sulphur and will damage the "convertor" now called a egr filter.#2-the dealer checked for codes and excessive fuel return rates-but did they check the injector balancing rates-being off caused by bad injectors will cause it to smoke and for any codes-if you have a programer on it,thats is running the pressure up and eating the injectors up.
Customer: replied 7 years ago.
I misunderstood fuel type question...only ultra low sulfer california fuel and I forgot to mention: at time dealer told me return rate and balance OK, they replaced MAF saying that was what caused excessive smoke...still smokes like a chimney. No programmer...bone stock
Expert:  frank replied 7 years ago.
No codes and good return rate would mean that the computer is not seeing a problem-I really question the balancing rate.Do you know any one that can put a scanner on it to see what the balancing rate and idle fuel rail pressure is.
Customer: replied 7 years ago.
can this scanner be rented at an autozone? or is it specilized to connect into the fuel line?
Expert:  frank replied 7 years ago.
I am used to higher end scanner-I dont know if auto zone rents them or if their quailty is good enough for the system you have.
Customer: replied 7 years ago.

I will return vehicle to dealer and request written report of items you suggest.



Expert:  frank replied 7 years ago.
ok-and yes-injectors are usually the cause of excessive smoke and that should beable to be seen on a scanner-the question is if the person working on your truck knows what he is looking for or at.Its seems that the knowledge part is lacking at the dealers lately.
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