Surging VRS fabia

[skudmissile]

Hi people,

And my problem for today is...... surging.

i have a fabia 2004 vrs with the asr engine. its done 32k had a new maf about 5k ago, no fault codes when scanned with VAG COM, serviced regular etc etc.

My problem....

If i slowly accelerate through a single gear say 3rd for example, the car will surge like its boosting then not then boosting.

it also does it at low rpms in second or first. like its stuttering but its not a BLT stuttering engine i am quite miffed

any ideas?


cheers in advance

john

[Chrispy]

Could be the potentiometer for the throttle control. It may be sensing a varying voltage hence the random power delivery. Perhaps?

[devonutopia]

well, if the MAF is ok, might be time to look at the boost sensor. This should come up on a fault code as well.

[skudmissile]

Originally Posted by devonutopia

well, if the MAF is ok, might be time to look at the boost sensor. This should come up on a fault code as well.

would i be right in saying the boost sensor is the one mounted to the top of the oem intercooler?

____
john

[skudmissile]

Originally Posted by Chrispy

Could be the potentiometer for the throttle control. It may be sensing a varying voltage hence the random power delivery. Perhaps?

it has been squeeking latley so might be worth a check tomorrow, its starting to annoy me as its not showing any fault codes.

[devonutopia]

Originally Posted by skudmissile

would i be right in saying the boost sensor is the one mounted to the top of the oem intercooler?

____
john

Yup indeedy - usually throws up a fault code when it starts playing up - i know mine did. Beyond that you'll have to think whether your MAF has gone already, and maybe look at the throttle pedal - quite rare for the pedals to pack in though I thought.

[skudmissile]

cheers jason, will try swapping the boost sensor......cant be that expensive and its an excuse to get the tools out.

I have only heard of them packing up completley and leaving people with cars that will only idle and not rev but never heard of them working intermittently.

thanks
john

[devonutopia]

I had one going intermittently - usual symptom was simply being thrown into limp mode as the sensor threw a wobbly - cutting all boost and giving me an SDI. Would usually reset by starting the car, but the gaps of full boost inbetween limp modes got shorter, so I got a new one. Think they're around £25 from the dealers. Is an easy swap for me as it's bolted somewhere quite convenient to reach.

[skudmissile]

Update here

Today i swapped the boost sensor from mine with one off our non surging 2006 ibiza fr (same part number) and the car is still surging.

I have also noticed that if you hold revs at 2300rpm you hear the turbo spooling and revs increase to 2500 rpm then the turbo stops spooling and the revs drop then the turbo spools revs increase to 2500 then it stops spooling and revs drop back to 2300rpm over and over and this is with holding the throttle and not moving it.

Is this normal?

cheers john

[Lummox]

It will be an ASZ engine. Really needs some diagnostics done on it. Guessing parts isnt going to help unless your very lucky,

[skudmissile]

Originally Posted by Lummox

It will be an ASZ engine. Really needs some diagnostics done on it. Guessing parts isnt going to help unless your very lucky,

Ive done a vagcom scan and its shown up nothing. appart from the dammed outside vent flaps not functioning but that can wait.

are you saying that the best thing to do is take it to a dealers?

cheers john

[Lummox]

I'm saying its best to take it to someone who knows the cars be it specialist or dealer.

Has the warranty expired now?

[skudmissile]

Originally Posted by Lummox

I'm saying its best to take it to someone who knows the cars be it specialist or dealer.

Has the warranty expired now?

No but it might as well have, all the dealers round me are usless.

I am quite competent myself but i have never had any experiance with the pd engines or turbo diesels.

I am pretty sure i have found the cause of my problems. one of the small bore pipes that runs to the actuator on the turbo has rubbed through on something.

Ive done a temp fix, which has done the trick, till i can get to work on tuesday for some new hose.

thanks for the help john

[Lummox]

Might well be rubbing on the engine cover.

[Windy]

Mine is exhibiting the same problem when hold revs when parked, which pipes should I be checking?

[skudmissile]

Originally Posted by Windy

Mine is exhibiting the same problem when hold revs when parked, which pipes should I be checking?

Id check all the pipes that run from the little black box on top of the drivers side inner wing. mine was the pipe that runs from that to the turbo down the side of the engine.


cheers john

[Windy]

Thanks John, Gonna go and check them now