Hi just wondering if any 1 could help me.

My forester turbo keeps jerking back like its going to cut out when in 3rd 4th gear and under pressure but it don't do it any other time, I've changed leads plugs map sensor all still not cured it any help is much appreciated

The only thing I can think of is changing mass air flow sensor but that does not seem like its a problem as she purrs like a kitten on normal tick over its just as I say when the car gets to temp and you put it under pressure about 4000 revs many thanks again,you can email me on scott_kittridge@yahoo.co.uk

Welcome to the USMB.

 

It sounds kind of like you may be hitting fuel cut. Are you running stock boost pressure? Does this occur only at full throttle or does it occur other times. Any additional details you can provide would be helpful.

Welcome to the USMB.

 

It sounds kind of like you may be hitting fuel cut. Are you running stock boost pressure? Does this occur only at full throttle or does it occur other times. Any additional details you can provide would be helpful.

 

Hi there it only does it under pressure when turbo kicks in if you hold ya foot on the gas it clears an boosts as normal until its ready to do it again in 4th it seems 2 be some sort of boost problem.been told to try a new boost cellanoid sensor? But keep changing things getting rather expensive now had it on a computer an no faults are been shown so now am at a loss as to what it could be I've just ordered a new bcs so fingers crossed after that only thing I can think of my self is a actuator but not a clue if it's that neither do I no if it's stock boost or not! I have put a 3" straight through on it thinking the old pipe was causing some sort of back pressure so really any help you might be able to give or thoughts would be usefull

Hi there it only does it under pressure when turbo kicks in if you hold ya foot on the gas it clears an boosts as normal until its ready to do it again in 4th it seems 2 be some sort of boost problem.been told to try a new boost cellanoid sensor? But keep changing things getting rather expensive now had it on a computer an no faults are been shown so now am at a loss as to what it could be I've just ordered a new bcs so fingers crossed after that only thing I can think of my self is a actuator but not a clue if it's that neither do I no if it's stock boost or not! I have put a 3" straight through on it thinking the old pipe was causing some sort of back pressure so really any help you might be able to give or thoughts would be usefull

 

Also it is the imported forester s/tb if this helps at all many thanks

It really sounds like fuel cut to me. The ECU will cut fuel to the engine if the boost pressure rises above a certain point for a certain amount of time, (usually a couple seconds).

 

Do you have a boost gauge or know how much boost you are seeing when you experience the problem? If you don't have a gauge, I would recommend installing one.

 

Installation of the larger exhaust, actually can cause fuel cut on a pretty much stock car. The reason is that the larger exhaust allows the turbo get rid of the exhaust gasses more quickly, which spools the turbo quicker and raises boost. The stock ECU boost control is programmed for the stock setup, so it likely is unable to lower boost enough with the larger exhaust and then trips fuel cut.

 

You can either have someone try and reprogram the fuel cut threshold in the ECU, and/or you could reprogram the ECU boost control or install an aftermarket boost controller.