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Discussion Starter #1
Howdy Folks, I'm new to this forum and am looking for a solution. About 3 months ago my 2004 2500HD Duramax started making a noise only when it was cold that sounded a lot like "spark knock" in a gasoline engine this took place only at 1600 to 1900 rpm's, dealer couldn't figure it out, no "service engine" light and no codes. About 2 weeks ago I was on an long drive up north and this "knocking" sound got to where it was there all of the time whether the engine was cold or at running temp and still at the same rpm range. Changed fuel filter, nothing happened, took it back to the dealer as soon as I got home and they reprogramed the computer all was good for about 2 days and now the noise is back but only when cold again. Dealer recommended using Lucas Fuel Treatment, tried it for 2 tank fulls no help! Now it has started having some hesitation for the first 8 to 10 miles when it is cold when you step down on the throttle, and the cruise control won't stay on turns itself off (not sure if this is related).

Has anyone out there had this same problem and if so please let me know, I have an appointment for next Monday at the Dealer again and hope they can find something. We are picking up our new 5th wheel in two weeks and plan to hit the road soon so I would really like to have this problem solved before than.:help:

Thanks,

Ron
 

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No problems here, but it sounds like an injector issue. Have the dealer check the injector balance rates to determine if they are within an acceptable range. You can check them yourself with a decent handheld programmer...info to be found here if you use the search feature.

Hopefully you'll get it sorted out soon.
 

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yep injector. had the same problem with my truck chevy did flow checks and found that one of my injectors was bad. took 5 days to get the new injector but it works fine now. got about 700 miles with no problems.
 

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Discussion Starter #4 (Edited)
Okay Folks, got my truck back last night and it runs really great and the excessive noise is gone. They really had a problem finding what was wrong, doing a flow test didn't reveal any bad injectors and they seemed to be well versed in troubleshooting "first generation" Duramax but not "second generation" like mine. So they called GM and finally got hold of a fellow who knew something about this problem, and that it is due to a bad injector. The GM rep told them to hook up their hand held computer and then one of them drive the truck and the other person operated the computer, they drove it to get it up to the point where they heard the noise then using their computer they started killing each cylinder one at a tiime until the noise went away. It was #8 injector they R&R'd the bad injector and everything is fine. GM rep told the dealer that they seem to be having a big problem with injectors and suspect it is due to bad fuel be produced since Katrina hit, they seem to think the refining process is being short cutted. Don't know if any of this is true all I know is my truck is back, WOOOOOOHOOOOO!
 

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Glad you got it fixed. Make sure you use a good Lubricity additive since in June the -:t ULTRA low stuff will be pumped in our tanks. Use Power Service in the silver bottle or FPPF Total Power. Good Luck
 

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Glad you got it fixed. Make sure you use a good Lubricity additive since in June the -:t ULTRA low stuff will be pumped in our tanks. Use Power Service in the silver bottle or FPPF Total Power. Good Luck
My Dealer Service Mgr. says GM has never reccommended a fuel treatment be used but since Katrina they have sent out a bulletin to suggest the use of a fuel treatment and the dealer suggest "Lucas" fuel treatment. Think I'll try the stuff you have suggested, thanks for the info.:D
 
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