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Discussion Starter #1
I have an '04 LLY Duramax that seems to have a strange pulse in it as though either fuel starved/recovered or a high-lift cam action (old racing days never really go away ;) ). It is prevelant at the top of the pedal while cruising or at idle. Not noticable during acceleration or decleration. Strong enough at idle at times to lurch the vehicle while brakes applied. There is no discernable pattern to when this occurs, but it seems to be stronger at cooler, damp weather than not. It is alway somewhat present at any temps and weather and engine temperature seems not to affect its occurance or lack of it. If anyone has experienced similar conditions, what have you done to correct it? Dealer Service Tech says GM Acknowledges the problem, but has no official repair to offer.
 

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I have a 2002 LB7 and when its cold or cooler temps the truck feels as its "fighting" the brakes....its kinda wierd but GM also told me they don't know what it is....maybe its the big bad allison trans that can't wait to get to work!!! :p
 

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Thanks for the reply, BigDog. I would agree that the Allison wants to work. I've used it with great satisfaction. But, my pulsing engine problem persists even when not in gear, so I don't think its in the tranny. I do think the transmission wants the problem to go away, though. When cruising and approaching a slight rise in the road, the transmission will suddenly find a downshift point that seems premature. I believe this to be connected to the fact the the engine pulse fools the tranny logic into believing the grade is greater than it really is. Again, thanks for your thoughts. I'd welcome more on the subject.
 

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Discussion Starter #4
Surge and Pulse Problem Fixed

My problem was fixed by going to a different dealer with a larger diesel shop. The problem occurred while being driven by their technician and he stood up to Chevrolet/GM and told them he it was dangerous and he would not release the vehicle back to me until they authorized a repair. They allowed the time and he ended up applying many computer updates and then replaced the fuel pressure regulator.

This is a known problem and those with it need to force GM to repair it.
 

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mine 02 is pulsing as I slow to a stop and when I let off the brake. Feels kind of jerky until I accelerate. Going to dealer tomorrow to see what it is.
 

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Yes there is reflash to fix this issue now i do beleive, contact a trust worthy dealer!!!
 

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Yes there is reflash to fix this issue now i do beleive, contact a trust worthy dealer!!!
Will the reflash erase your program\tune if you have one in the truck?

I bought it preloaded and I do not have the handheld Bullydog.... :(
 
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