Rough Idle, Smoke odd balance rates - Chevy and GMC Duramax Diesel Forum
06-07 LBZ & LLY Duramax Powertrain Discussion of components that are directly involved in the power production and all that is needed to get and keep the truck moving . Engine , Transmission, Etc.

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post #1 of 1 (permalink) Old 10-05-2019, 09:42 PM Thread Starter
Join Date: Aug 2019
Posts: 6
Rough Idle, Smoke odd balance rates

I have an 04 lly duramax, that I bought about a year ago. Recently it started to have an intermittent rough idle when warmed up, in gear and stopped as soon as I take off it runs fine. I have also noticed that if i just barely touch the throttle weather it is rough idling or not it acts like your engaging the clutch on a manual with out giving any throttle, (my truck is an automatic) . On one occasion I had a lot of white smoke and one other occasion blackish blue smoke. My balance rates are all over the place, all injectors are out of spec from +10 to -7. a week ago one was +10 one was +5 the reset were less than three. This all started about a week after I changed the oil, fuel filter and cleaned the air filter. since then I have ran a bunch of injector cleaner, I even got my hands on some of the old gm upper engine cleaner. while doing that cleaning I noticed tiny bubbles in the return line so I replaced all the rubber fuel lines on the suction side of the fuel system, and rebuilt the filter housing. All this seemed to make the rough idle better but the injector balance rates worse. The odd thing is some times it runs and idles fine and the injectors are all within spec. I have looked over the wiring harness and haven't found any damaged wires. the demand and actual fuel rail pressures are within .2kpa of each other while at idle though the actual pressure fluctuates a bit. I am going to try and ice pick the injectors soon to see if that has any effect. If that doesn't help does anyone have any other ideas to check? I know it looks like I need new injectors but I am hesitant that with the sudden onset and it affecting all the injectors and it being intermittent that there is something else going on and I don't want to drop 3 grand on injectors and it not clear anything up. I don't seem to have any power loss, and my fuel economy is 18-20mpg on the high way going 65. The truck is EGR deleted with a straight 4" exhaust, Cat filter upgrade, lbz mouth piece, PCV reroute I think its tuned the edge CTS has power levels I can change between though I cant tell the difference between them, but it doesn't through a code due to the EGR delete.
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