First problem, help please!

[nesshead6]

Hi folks, my car has developed an intermittent problem (already!) basically the car wont rev beyond 2000, when I put the foot down the engine suddenly "cuts out" just as the turbo kicks in, the engine is still running but I keep my foot down and the same thing keeps happening. The problem only stops by switching the ignition off and on again. This has happened a couple of times now, both times after approx half an hour of driving.

When plugged in, the fault code from the ECU reads that maximum boost pressure has been exceeded. Suspecting that the boost valve is faulty (the one in the pipe between the air mass meter and the turbo inlet)? My flatmate has a spare boost valve from his RS2 and has offered me it to see if this solves the problem, I'm not sure if it's exactly the same though, does anyone know?

Anyone else with knowledge or experience of this problem, your help would be appreciated!

Thanks

[s2_bo]

You can use a RS2 WGFV (boost valve) to test your car.

Did you get any other fault codes?

Also maybe try unplugging the WGFV and see if the car still does the same, you will only got spring boost so about .4bar while its unplugged but its worth a try.

How much boost are you seeing normally?

Could also be an air leak, or a faulty maf or maybe knock sensors.

Good luck.

[haaran]

Check for a boost leak in all the pipes in/out of the turbo and intercooler. Make sure there are no holes or cracks in any of the pipes, particularly under the clips. Give all the jubilees a quick tighten aswell if you can.

[Ross]

Sounds like a possible boost leak, causing the turbo to overboost to compensate... If you ca get a bung to go into the MAF-turbo hose and pressurise the intake it can be tested.

InRS2 WGFV will work on the S2 and yes, this would be a good thing to test as could cause the overboosting also. Unplug it and see what happens - perhaps a quicker way to test it (should rev OK but get 0.4bar boost max).

This is assuming the car is standard (ie stock turbo, no chip or winding the WG spring in etc)

Cheers
Ross

[Rusty]

Welcome to the wonderful world of boost leaks...

Contact AndyP and get a testing kit then find somewhere quiet and try to resolve every little leak...

Oh, and good luck

Where are you based? There might be someone locally who can help you.

[nesshead6]

Thanks for the advice guys. The car is standard, not sure exactly how much boost when running normally. I'm gonna try running with the WGFV unplugged and also with spare from the RS2. This might take a while though, as it is an intermittent thing and (at the moment) the car runs ok more often than not. So think the best thing to try and eliminate first will be leaks from any of the hoses...

Rusty, I'm in Falkirk (scotland) and the aforementioned flatmate with the RS2 also happens to have his own garage locally. I'll be down there asap to use the smoke machine...

Thanks again

[s2_bo]

Check your two knock sensors and the wiring to them, if they go they can course what you have described above, essentially as its intermittent.

Also they can fail with out giving a fault code, at least thats what happened on my s2. Turned out one of them had exposed wiring where the rubber cable had perished.

You can find them under the Inlet manifold about half way down the block. There is two

[Audi-Porsche Avant RS2]

Hello, in my S2 Coupe ABY I had the same problem, I had check for boost leak, bad N75 or wastegate spring or wastegate membrane, I had change also the MAF and I had always the protection when overboost turn on with the same error that you have too, 00544 boost pressure to maximum exceeded, finally I have change the ECU because when I test it for code I read also 65535 error code, control unit faulty (ECU), I think that is probably that my old ECU have the boost pressure sensor damaged because the owner of the car before me had put some thicknesses in the wastegate for have more boost pressure and is possible that have damaged it.
You can try also the boost pressure when your ECU cut out with a boost gauge, you can mount it with a T pipe in the pipe that is in the car connected with the ECU, the boost pressure for a original S2 ABY are about 0,85 bar normally and 1,15 bar in overboost.

Alessio

[nesshead6]

Hi, I have also been thinking that the ECU itself may be faulty. I hope not...

Just for a quick update, I have used the car a couple of times, including a 120 mile run on sunday, and the fault has not yet happened again. So I'm not convinced that there is a boost leak given the intermittent nature of the fault. Surely if there was a leak then this fault would occur every time, and would progressively get worse? So, so far I haven't done anything as I'm kinda hoping to work out roughly when/why it's happening although I do have the spare WGFV ready to swap in as soon as it's needed.

Alessio and s2_bo thanks for your suggestions, going to have a look at the knock sensors today if i get a minute...