Used my car today and found down on power.

The boost gauge is only reading a max of 5psi (normally 20psi as remapped).

Boost is so low you cannot hear the dump valve.

Also when foot to the floor it is hesitate and seems to misfire sometimes.

Took it on the local dual carraige way and tried to give it some but again little turbo boost.

Any suggestions on how to sort this would be greatly appreciated

Note I quickly checked the hoses to intercooler etc but havent checked hose to turbo.

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Check those 2 hoses , as they are the most common to fail

Sarah

Thanks for the quick reply Sarah

Quicky checked the hoses you showed and found a small split in the upper pipe.

Tried using tape to cover hole but the location of the split I dont think tape would have made it air tight.

Infact when I took it for a spin it didnt make any difference.

I will source a new pipe after the bank holiday monday and hopefully this will fix the issue -unless another hose is split :(

Thanks again for the info Sarah much appreciated -will probably order some of the upgraded hose when my bank balance returns to normal after the xmas!

No problem my dear

The claw one is quite easy to replace , a bit better than the one below it , so thankfully a good one

The hoses from the dealers are quite expensive though , approx £28 ish

IIRC there is a part number in that link too , so hopefully you wont have to go trough all the messing with the dealers too

Nice one , glad you got sorted

Sarah

Changed the top breather pipe (y -shaped) after getting part from TPS.

Unfortunately still the same -max boost of 5psi.

The boost gauge seems to be reading a high vacuum at idle, with a reading of 20.

Cant remember if this was the norm or not?

Suppose its a case of checking every other hose on car.

I have also checked the bottom breather pipe by blanking this pipe off but again still the same.

Any other suggestions appreciated

Changed the top breather pipe (y -shaped) after getting part from TPS.

Unfortunately still the same -max boost of 5psi.

The boost gauge seems to be reading a high vacuum at idle, with a reading of 20.

Cant remember if this was the norm or not?

Mine on tickover reads -15 to -20, so yours sounds about right.

Maybe the N75 has gone for a bit of a sh!t? I know that controls the boost.... Might be worth checking and cleaning the connections on that...... also might be worth checking the MAF as this can cause all sorts of problems when they start to fail.

Did you check the T.I.P? Just wondering whether your plugs/leads are shot causing the misfire...... Cars, a major headache!!

Best of luck in getting it sorted Michael.

Steve

thanks for the advice mate.

I have a spare N75 valve so I will fit that tonight.

If that doesnt work then the MAF and then I will jack car up and check hose to turbo.

Ive already tried a spare dump valve but still the same.

Suppose just a process of eliminating different parts -cars what a headache

A vag-com scan might also help...

Well still no further forward..

Swapped over N75 valve but still the same.

Checked TIP and all auxiliary hoses -all seemed ok

Tied spare dump valve but still the same.

Tried cleaning MAF but again still the same.

The only thing I havent tried is running the MAF disconnected.

Will this bring a fault on the dash?

Suppose I will have to bite the bullit and get the dealers to check using VAG COM

Coilpacks all OK?

You should check it with vag-com and also do this; http://www.a4mods.com/index.php?page=webcontent/pages/boostleak.html

The disconnected maf will bring a CEL, but after you reconnect it it will go away (after several power ons/offs).

Wastegate stuck open maybe? You might be able to tell by looking at the position of the actuator rod.

Or loose bolts between manifold and turbo?

Just had VAG COM check by MB Motorsport and it brought up the following:

16621-mainfold pressure/boost sensor:(G31) signal to low

16490-manifold /barometric pressure sensor (G71)/(F96) -implausible signal

17705-pressure drop between turbo and throttle valve (check d.v)

MB motorsport to busy to investigate more but suggest MAP sensor might be worth changing.

Got a price for £40 from TPS-is it worth changing this or more checking of hoses required?

Any suggestions and previous ones much appreciated

i'd bank on the sensor, fits in the intercooler pipe and controls boost pressure

Did you get an engine light or did you only realise there was a fault due to your boost gauge?

Pretty sad replying at this time I know, but he I have kids so no partying vor me!

Right, thanks for the replies including bond007.

Unable to pickupspare MAP sensor today so will get on saturday, thats if I manage to get the old one off!.

The 2 x allen bolts holding it on were roundered so i drilled them off and removed the sensor.

However I cannot remove the remaining bits of studing, tried everything seems as though the thread has fused its self to the base plate.

Will probably have to take the forge intercooling pipe off the car so I drill out and retap holes!!

Replying the the last message -I knew about the issue as car felt very slow, no acceleration and by checking my boost gauge it was only reading 5psi instead of the usual 20ps(remapped).

No such thing as a 5min job!

Finally got car running again 100%

Changed the MAP sensor first thing and took it for a drive -still only boosting at 5psi

Spent rest of day checking every hose for leaks -no found.

Decided to then strip baileys dump valve and give it a grease -took it for a spin and now perfect!

I had already tried my spare standard dump valve the previous day and this didnt make any difference.

Dont understand -at least its running again.

Only gripe was I ripped off my front splitter again (twice in the last 2 weeks) due to lots of snow/ice on roads!