hi,my vrs has a annoying turbo boost fluctuation. on hard acceleration the boost goes up to 11 psi then drops down to 8 psi then just keeps going up and down, after about 20 seconds it levels off at just under 10 psi. the problem has got worse since the decat was fitted.

any ideas what maybe causing this?

standard map

milltek exhaust and decat

pipercross panel filter

uprated recirc valve

cheers

Edited 29 September, 201114 yr by VRS Dyson

Try fitting a new N75 valve. Mine had exactly the same probelm as yours and a new valve fixed it.

Try fitting a new N75 valve. Mine had exactly the same probelm as yours and a new valve fixed it.

thanks, i will get a new valve. where is it on the car? is there any way of testing it to see if it is faulty??

cheers

It`s not N75, you have a problem with a fuel pump. It cost around 50e.

Best regards

Could it be the fuel filter? I dont think its been changed.

Cheers

That will be the N75 boost controller solenoid.

Here is an old (standardish) picture of my car...

HTH

Steve

Could it be the fuel filter? I dont think its been changed.

Cheers

I change mine every 5k or 12 months. For the sake of £10 for a genuine filter it will keep everything running smooth[er].

Steve

Could it be the fuel filter? I dont think its been changed.

Cheers

Exchange it but if the problem continuous, your fuel pump is failing. Trust me, I had exactly the same problem after installing Milltek exhaust.

Try ed everything, spended **** load of money.

If you can go to some shop that have fuel manometar and connect it to fuel rail. On idle pressure should be over 4.5bar (I had 4.9bar) and in full boost around 3.9-4bar. If it`s less then that you know what to do...

Good luck!

Exchange it but if the problem continuous, your fuel pump is failing. Trust me, I had exactly the same problem after installing Milltek exhaust.

Try ed everything, spended **** load of money.

If you can go to some shop that have fuel manometar and connect it to fuel rail. On idle pressure should be over 4.5bar (I had 4.9bar) and in full boost around 3.9-4bar. If it`s less then that you know what to do...

Good luck!

Correct me if I'm wrong but 4.5 bar of fuel pressure @idle seems way to much. And surely the fueling should rise on full boost not go down ???

While on my way home it has started boosting up to 14 PSI and the boost gauge started rattling. :(

You need a scan first, check the vcds section for a user near you

I doubt that is to do with the fuel imo

If you can go to some shop that have fuel manometar and connect it to fuel rail. On idle pressure should be over 4.5bar (I had 4.9bar) and in full boost around 3.9-4bar. If it`s less then that you know what to do..

Pressure is too high.

For all the work and power my engine produces my Sard regulator is still set at 3bar. High fuel pressure is normally only required when your injectors are too small.

Lower pressure with good size injectors is safer, and an all round better deal.

Steve

I am talking about pressure before fuel rail, the pump is pumping on idle 4.9bar, the FPR of 3bar is there to regulate the pressure in the fuel rail. Extra fuel is returning to a fuel reservoir.

There must be a difference in pressure so the fuel pressure regulator can actually regulate the pressure.

If the pump pressure drops below the fpr pressure, there is nothing returning to the reservoir and in full boost the injectors are almost fully open, the pressure inside the fuel rail actually drops bellow 3 bar.

Lack off fuel is manifested what Dyson described in his first post.

Lambda correction factor in crises over 20% and ECU try to protect the engine by reducing the boost.

Edited 30 September, 201114 yr by Gonzaga

Correct me if I'm wrong but 4.5 bar of fuel pressure @idle seems way to much. And surely the fueling should rise on full boost not go down ???

No it wouldn`t, fuel pump has only one speed of pumping. Fueling is controlled via ECU->fuel injectors

Ive booked it in at skoda for a diagnostics session next friday. so hopefully will get an answer.

Ive booked it in at skoda for a diagnostics session next friday. so hopefully will get an answer.

Well skoda were useless. they didnt even want to.look at it. i had a good look round the pipes and found a split in one of the hoses connected to the n75 valve. ive repaired it and it runs sweet now.

You must have taken it to my local dealers then Glad you sorted it

you can buy a diagnostic reader from ebay for £30. Glad you got it sorted though.

you can buy a diagnostic reader from ebay for £30. Glad you got it sorted though.

I have a diagnostic reader but this particular fault did not trigger the cel light to come on, therefore no faults to read. The origional conversation i had with skoda was that they said they could detect any problem with there diagnostic equiptment and aparantly it would check fuel pressure and vacum system etc. i thought the bloke was full of crap, when i went down they said if the cel light isnt on they cant trace the fault and that the fault was because i had modified it.

Edited 11 October, 201114 yr by VRS Dyson

I have a diagnostic reader but this particular fault did not trigger the cel light to come on, therefore no faults to read. The origional conversation i had with skoda was that they said they could detect any problem with there diagnostic equiptment and aparantly it would check fuel pressure and vacum system etc. i thought the bloke was full of crap, when i went down they said if the cel light isnt on they cant trace the fault and that the fault was because i had modified it.

R-tech are only up the road from you. I'd use them bud no bull****e from them. Christ I use them and I'm near Oxford.