At top end my octy jumps on and off boost, any ideas why? I just changed a few perished breather pipes for silicone Creation Motorsport hoses.. did the same thing before I changed the breathers..

 

Haven't checked it with a diagnostic scanner yet but will do tomorrow.

 

I been told giving the throttle body could be a little help.. any other suggestions that could help.. or could be worth doing while im at it..

Mine went like this a couple of years ago - turned out to be a faulty MAP (or was it MAF?) sensor. Whatever it's called, it's the one that sits in the intake pipe trunking, leading from the airbox to the turbo - it sits upstream of the dump valve.

 

If you unplug this sensor and go for a drive (you'll get fault lights on the dash but don't worry about it) and the car drives 'ok' - i.e. not with it's full performance but smooth and linear to the redline, without 'surging' and fluctuating boost - then you know it is this sensor which has failed.

 

Then just buy a new one and it's a TMJ to replace it.

Mine went like this a couple of years ago - turned out to be a faulty MAP (or was it MAF?) sensor. Whatever it's called, it's the one that sits in the intake pipe trunking, leading from the airbox to the turbo - it sits upstream of the dump valve.

 

If you unplug this sensor and go for a drive (you'll get fault lights on the dash but don't worry about it) and the car drives 'ok' - i.e. not with it's full performance but smooth and linear to the redline, without 'surging' and fluctuating boost - then you know it is this sensor which has failed.

 

Then just buy a new one and it's a TMJ to replace it.

Oh Forgot to add.. I'm already running it without a maf.. so that cant be the problem.. or could it?

Oh Forgot to add.. I'm already running it without a maf.. so that cant be the problem.. or could it?

Explain ....

Could be fuelling crapping out you. Lots of people forget the fuelling.

An unplugged maf would do this yes because.... as explained to me before..

 

The ecu doesn't know at the given time how much air is entering the system thus guessing how much fuel to dump in and consequently boost to give you.. And will always chick more in than nessecerry to save running lean.?..

 

Then the ecu gets a reading from the lambda sensor and govens the next cycle fueling wise. So it's always trying to second guess itself.!

 

Get a maf and plug it in. When you do, disconnect battery neg for 15 mins which will delete eml... then report back.

 

I'm also running with maf unplugged because mine buggered (vag com told me so) so I've given up on the "boost" ect threads until I get my new one next week. 

 

Map sensor is another suspect but get a maf first mate 

Edited 12 April, 201412 yr by LuckyvRS20vT

Ordered a new maf so will give it a try in a few days when it arrives, Another thing ive read is it could be the dump valve seal and now that I looked at my dump valve I don't have a jubilee on the intake pipe part so that could be a possible suspect 2 but did give it another going yesterday and it pulled well as it should no surging or dipping in and out of boost..