What the hell happened to my boost?

[Pisobiker]

Hi guys.

It's a couple of days my car doesn't boost anymore.
Just the "limp home" boost of ~0.85 bar all the way to redline.

Car runs perfectly and smoothly, no hesitation on any rpm. Just doesn't make the 1.7 bar boost anymore!!!

Mihnea, how come the board computer say:

"This software has expired, to buy a new release contact your software provider"



just kidding, M8. but the problem is real !

- WGFV is ok;
- Fuse is ok;
- WG is fine;
- Pulled fault codes and only got 2111;
- If WGFV unplugged I get 4442 which seems right;
- Leak test done, OK;

WHAT THE HELL DID HAPPEN !!!

[audiman]

try that damn temp sender in the water rail! If you unplug the git, it should run at normal boost(?) if its at fault.

[Pisobiker]

Tom, do you mean the multi function temp sensor?

[Pisobiker]

But if too high temps or faulty sensor, shouldn't than give a fault code of any sort?

[audiman]

yeah thats it. Did you notice what the coolant temp was reading on vag-com(not gauge)? It uses this to see if the car is super hot and so turns the boost back.

[audiman]

If it is faulty, or you have a poor connection on it then it will still display a temp, it may be a high temp but the ECU just thinks that its real, even if its like 150C

[Pisobiker]

I don't have Vag Com, Tom. I pulled the codes out from the fuse box with the "S2Central" trick.

Will check this thing of the temp sensor immediatly.

Ciao


Marco

[Glen Chamberlain]

Tried MAF and connection?

[Pisobiker]

Yes Glen, was one of the first things I checked before pulling out fault codes.

Anyway the problem was the damned multi function sensor, as suggested by Tom, I unplugged it and the boost come in again (but the temp. reading on the dash disappeared ).
I was aware those sensors sometimes fail, but actually thought the ECU would have stored some fault code for it as well.

Will change it after the "Italina job" will be completed. Don't have enaugh time now.


Thanks Tom


Marco

[Mihnea]

Marco, I'm glad to hear it was only that, it was also what I was about to suggest you if Tom didn't do it first....

The MFTS doesn't induce any fault codes, as its failure mode shorts the overheating switch for the ECU (120°C) and the ECU doesn't see any faults, even though it's stupid as it could figure that the water temp sensor (G62 at the back of the head) doesn't say the coolant is overheating....

Oh well, run with it unplugged for now, you'll be fine!

Mihnea

[audiman]

Cheers Marco!! Ahh right again! Wish I could cure my own car as well as others

I havent even seen your car. LOL

That sensor is a weird one, my car still has the original one in it, just waiting for it to pack up. Sould have died years ago its now nearly 13 years old!!!