hi, under acceleration my rs surges then holds back with a distinct rhythm, it rocks u in the seat in 4th n 5th gear its that bad, no error codes, but fuel consumption is erratic to say the least, cruising its may be doing 40+ then drops to 30 for no reason and the car seems down on power some of the time, any good ideas??though of fitting a boost gauge to see if boost surging??

noticed some oil on turbo outlet pipe at back of engine but nothing to concern me.

help.john

Try disconnecting the MAF. If the problem's no worse, or better, replace it.

Otherwise if sounds very like fuel starvation, so try replacing the fuel filter.

where is the fuel filter on the vrs??certainly not been changed for 20k

Forward from the drivers side rear wheel underneath the chassis. IIRC its meant for the life of the car but a swap cant hurt.

I'm pretty sure the service book recommends changing the fuel filter every 60,000 km

Airmass Meter? Didn't flag anything up when mine started surging but I disconnected it and it worked fine afterwards.

hi, under acceleration my rs surges then holds back with a distinct rhythm, it rocks u in the seat in 4th n 5th gear its that bad, no error codes, but fuel consumption is erratic to say the least, cruising its may be doing 40+ then drops to 30 for no reason and the car seems down on power some of the time, any good ideas??though of fitting a boost gauge to see if boost surging??

noticed some oil on turbo outlet pipe at back of engine but nothing to concern me.

help.john

This sounds very similar to the issue I had, hough yours sounds more pronounced.

My problem was the turbo intake pipe had come off the turbo, but at some point my MAF had also failed, probably by trying to over adjust itself to compensate for the erratic readings it woould have been getting.

Unless you have an aftermarket TIP it's almost impossible for that to have come off but it could be a split pipe elsewhere.

when mine surged it was the DV needing an adjustment, if your car is mapped try this 1st.

Hi john, from what you are saying, it is possible that your N75 valve has given up, i have fixed a couple of 1.8t's with the symptoms you have described by replacing the said valve. The best way to check this is to unplug it and to take it for a drive and see if your symtoms clear up.

hi, i've ruled out pipes as it comes n goes, when it is cold it seems to perform far better and be more economical. the n75 valves had me wondering as it may explain the lack of go at times. will try unplugging n see what happens.thanks

Hmm, mine does this a bit too lately i've noticed. If only half putting my put down it can surge in some gears. It's fine if you floor it though, just over half throttle it seems to do it...

Getting a service / mot in a month so will see if they can pick up on anything!

My car also done this until i changed the lower IC pipe.

Hi guys,

Ok, fancy getting mine sorted now. Two of you have suggest unplugging the N75 and the MAF.

How do I unplug these? It is simple a case of pulling a plug out, can this harm the car?

The MAF plug is just to the left of the airbox on top of the big circular pipe as you look from the front of the engine. The N75 is the little valve with the small hoses going to it at the back rh corner of the engine.

I would suggest doing this test with the MAF only. I believe unplugging the N75 will effectively disable your turbo, and probably put the car into limp mode.

It's been suggest a couple of times in this thread so I doubt it would?

OK you know best.

The N75 is the wastegate control valve. Unplugging it will cause the turbo to be either on all the time or off all the time (hence my use of probably above, since I'm not sure which). This means you will either have no boost at all, or potentially be overboosting and damage the turbo. Your choice.

More info here

Ok, relax. I wasn't having a go...

Just saw it suggested earlier on and people had success! Guess I won't be able to just unplug it and see if that's at fault then :(