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Discussion Starter #1
Hey guys quick question i have a 2005 LLY and ever since i put my 3" MBRP DP and 5" turbo back exhaust on it idles differently but only when im in drive and stopped at a stop light or something. It kinda acts like it has a lope feel to it. Any ideas what may be going on? I dont have the egr blocked either just the DP and the exhaust. :help
 

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Does it go from the whistle, to a v8 rumble, back to the whistle/whine? its the vanes in your turbo. LLY and up trucks have variable vane turbochargers. The vanes check their limits by opening and closing to ensure they are still working correctly and to adjust if needed. Kind of a self test system.
 

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As nvrplzd said it is either your vanes opening and closing. If it is actually loping, like you can see the needle on your tach bouncing around it may be your fuel pressure regulator.
My LLY had a small lope and it was from the FPR.
 

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^good call indeed! didn't even think about that since he just mentioned it in drive. Tunnel vision again fvcks me! Nice save :drink
 

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Discussion Starter #6
Does it go from the whistle, to a v8 rumble, back to the whistle/whine? its the vanes in your turbo. LLY and up trucks have variable vane turbochargers. The vanes check their limits by opening and closing to ensure they are still working correctly and to adjust if needed. Kind of a self test system.
Yes thats what it sounds like kinda a V8 rumble...So thats normal then and no worries?
 

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Discussion Starter #7
As nvrplzd said it is either your vanes opening and closing. If it is actually loping, like you can see the needle on your tach bouncing around it may be your fuel pressure regulator.
My LLY had a small lope and it was from the FPR.
Is it bad if it bounces i mean my rmps go from 665-700 on my insight it just bounces a little i guess... never really noticed it until the DP and exhaust was put on
 

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my truck just did this two weeks ago. the whole thing shook and loped as I was leaving the house. New fuel filter and is now fixed
 

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can you notice the needle jumping on the factory tach? I would lean towards it being completely normal, as the sounds you are describing are normal. You said it ONLY happens in drive, correct? Not all the time? That would be the key indicator whether it is one or the other..
 

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I would say it's just the vvt doing it's thing.
 

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If its going from whistle to rumble and then back the whistle then its just the vanes cycling.
If its surging consistantly like you have an aftermarket cam in drive when youre stoped then it sounds like the FPR. My truck surged when I was stoped in drive and I replaced the FPR. Now it idles perfectly smooth.
 

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Discussion Starter #14
When do you check injector rates when the motor is cold or warm? Also my insight keeps sending me a warning sometimes saying my VVT pos is 100% what does that even mean?
 

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try running some 2 stroke in the fuel, smooths mine out.
 

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Try running the injector cleaning service. It is really simple takes about 1.5-2hours.
 

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your good my edge shows vane position and they will open and close and when they close it sounds like v8 rumble
 

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does it smoke at all? sometimes when i stop at lights mine rumbles almost like a gasser does with it's missing and huffs small amounts of grey smoke. does it very rarely.
 

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only hppens in drive. if it's in neutral or park and not under a load it's fine.
 

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Just checked my balance rates and the number 8 was at 12 is that bad?
Yeah, that definitely sounds like a bad injector, use 32oz of Diesel Kleen in a tank to see if it clears up at all. That injector could be part of the issue but if you have a CTS, then check demand fuel rail pressure vs actual fuel rail pressure. If at idle you watch the actual rail pressure bounce around alot then you probably have a bad FPR (make sure you have a new fuel filter on there before testing).
 
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