Surging when cold.

[Kol12]

Hi, my 99 B4 has started surging but only when the engine is cold, it seems to behave normally when warmed up. Any ideas?

[Rosssub]

Power surge while cruising cold? Probably the pre-heater in the O2 sensor dying.

[Kol12]

Yes, it only surges for the first few minutes driving from being started cold..

[hunter951]

off throttle surge or on throttle?

[Kol12]

on throttle..

[loner]

My BP5 does the same, but I came to the conclusion that it could be any number of sensors, and since it was only a problem for the first 60 to 90 seconds of driving in the morning, that I wouldn't worry about it.

[Guitar_Guy]

My '00 BH5 did the same thing, only when cold but only when coming on to boost. Asked a couple of mechanics and they said not too worry so took their word for it.

I rarely hit boost when it was cold though so never really bothered me and nothing came of it in some 15,000kms before I sold it.

[Kol12]

Its been quite bad a couple of times, it really hesitates just before hitting primary boost then really boosts when it does, almost abnormally. Then as you slow down to turn around a corner it repeats itself. This is all of course until the engine warms up though.

I usually tame my primary boost when driving from cold but it's hard to not hit boost in the B4's with the primary coming on so low..

I'll ask my mechanic about it I suppose but if it's heaps to repair I'll leave it for now.

[Andy_Mac]

Mine used to do the same. Used to start stuttering from a bit below 0psi. There was a RPM I could keep it below and it'd never happen but can't remember what that was anymore. The more load it got the bigger the stutter. Was fine when flat as I could keep the load down but since the first street out of my one was a sizeable hill keeping it from happening was a struggle. Never tried the o2 but someone had mentioned AFM which I swapped with a known good one which did diddly squat

Edited March 17, 2016 by Andy_Mac

[calebwrx]

Mine does the same. It's always bothered me but I was told it's nothing major. Sometimes it's quite bad and the car jerks around pretty bad and just makes me look like I can't drive

[Kol12]

Wow, a lot of people experiencing the same thing. It must be something though, maybe my mechanic will know.

[jsdub1]

I know this thread is a bit old but I thought I'd share. I had lots of jerking around when the car was cold and lots of misfires as well. Usually drove normally when it was warm. Turned out to be contaminated fuel. Pull your pump assembly, any contamination will be obvious (mine was a nasty looking white slime). Ended up killing an injector. Lots of cans of fuel treatment / system cleaner later and it still comes back from time to time so I will be dropping the tank and replacing this summer.

[loner]

 jsdub1 said:

I know this thread is a bit old but I thought I'd share. I had lots of jerking around when the car was cold and lots of misfires as well. Usually drove normally when it was warm. Turned out to be contaminated fuel. Pull your pump assembly, any contamination will be obvious (mine was a nasty looking white slime). Ended up killing an injector. Lots of cans of fuel treatment / system cleaner later and it still comes back from time to time so I will be dropping the tank and replacing this summer.

Were you using an ethanol blend?

[Rubesube]

Done alot of research on this problem and pretty much most the time will be these few things. Front o2 sensor , afm, fuel pump , spark plugs and least common to cause those symptoms is a vac leak. The o2 sensor wont always throw a ecu code , but is the most common fault.