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Discussion Starter · #1 ·
I have a 2001 Duramax with 99,000 miles on it. Early on I took it in to several dealerships to check out a surging/ fluttering problem at idle. The most I got out of the mechanics was that it might have an injector that was a little weak, but certainly not serious enough for replacement. I've continued to hear about all these injector problems and horror stories after they go to working on the engines, so I'd just resolved to drive it until something bigger happened. Now the fumes from the exhaust have gotter particularly bad. The fluttering really isn't any worse, but the fumes at the tail pipe indicate that the combustion is really poor at idle. What do you think? Should I take it to a GMC dealer or find an independent mechanic to work on it?
 

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Where are you located? I would find someone who has EFI Live or a Tech 2 and have them check the balance rates of the injectors. Should be looking at +6/-6mm3 in park and +4/-4mm3 in neutral.

What does the exhaust smell like? Fuel, oil, etc...

Steve
 

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Discussion Starter · #3 ·
I'm located in Myrtle Beach, SC. The fumes are unburnt fuel. Is there a anaylzer in the exhaust system that sends feedback to the fuel control system? Can you tell me in simple terms what is special about the analzers you mentioned? I sure appreciate the help!
 

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On your truck LB7 (2001-2004)1st Generation Dmax and up to 3rd Gen LBZ there is no senor in the exhaust. Only 2007.5-up have exhaust sensors.

EFI Live is tuning software that allow to read and alter the ECM. So its part Scan Tool and part tuner.

Tech 2 is a scan tool that dealers use. GM only.

Those the specialized scan tool, scanner, etc...
Any major scan tool (Snap On, Mac, Matco) should be able to check the balance rates and codes.

Did you have any codes when mechanics looked at it. Codes really help diagnose the problem.
 
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