Surgine question

[freebird01]

well it seems that I am mr. roadtrip lately. im stuck in dover,DE till wednesday and im bored sitting in my hotel room.

i noticed that when im driving my truck and in 2nd or 3rd gear and just lightly on the throttle from upshifting. like just enough to keep speed maybe a bit better and at the lower rpm it runs like i would expect it too with no boost...once the rpms start comming back up as occurs with slow acceleration in a selected gear...the boost will pick up and the truck will surge and take off almost like a runaway up to 7-8psi of boost....this is without me moving my foot...not pessing harder or softer...not moving. the rpms race up quickly too....then it his that 7-8psi and it levels off at a high rpm for the gear.

happens in 2nd and 3rd. not in 1st,4th or 5th..

any ideas?

 

[funnyman06]

Typically surging like that is related to air in the fuel system. As air reaches the IP it advances the timing and creates that surg you feel.

 

[freebird01]

its deffinitly repeatable. i would have thought air intrusion would be more erratic???

i dunno...just noticed it recently.

 

[Agnem]

How many miles are on your IP? The advance piston is a common wear item, and when it starts to go this can be a symptom. Try running about 50% WMO in your fuel. This thickens it up some and can temporarily stop the symptom if that is the cause.

 

[freebird01]

it only does it as the turbo spools....never without it...


mel...i cant say for 100% certain but its easily plausible that it is original to the truck and the truck has 116-118k (cant remember anymore)