Boost problems....

[UrS4boy]

Lambda Probe Heating

And I quote:

"Lambda Probe Heater

Lambda probe G39 is heated.
The lambda probe heater is switched on and off via relay J208 by the Motronic control unit.

Switching on Conditions:

If the intake air temperature is below 16oC (intake air temp sender G42) when starting the engine, the lambda probe heater will be first switched on after the engine temperature has reached 40oC (coolant temperature sender G62).
This is for protection of the lambda probe. Any condensation on the lambda probe can evaporate.

If the intake air temperature is above 16oC when starting the engine, the lambda probe heater is switched on immediately.

Switching off Conditions

The lambda probe heater is switched according to a map and depending on speed.

Lambda probe heater is switched on at idling speed."

That is just info. I don't think it is your problem.

[UrS4boy]

It also be the inlet temp or water temp sensors that are playing up.
If they misread and tell the engine is to hot it will cut the boost of

My guess is the intake air temperature (IAT) sensor located near the throttle body as shown here:

http://forums.audiworld.com/s4s6/msgs/148742.phtml

Should the G42 IAT fail or be disconnected, then the ECU is fooled into seeing a high temperature (of approx 40 degrees C) and boost is reduced accordingly. Info about the G42 IAT and what happens when it fails (and how to check, including a link back to S2central) is found here:

http://forums.audiworld.com/s4s6/msgs/148740.phtml

[bigdan]

And I quote:

"Lambda Probe Heater

Lambda probe G39 is heated.
The lambda probe heater is switched on and off via relay J208 by the Motronic control unit.

Switching on Conditions:

If the intake air temperature is below 16oC (intake air temp sender G42) when starting the engine, the lambda probe heater will be first switched on after the engine temperature has reached 40oC (coolant temperature sender G62).
This is for protection of the lambda probe. Any condensation on the lambda probe can evaporate.

If the intake air temperature is above 16oC when starting the engine, the lambda probe heater is switched on immediately.

Switching off Conditions

The lambda probe heater is switched according to a map and depending on speed.

Lambda probe heater is switched on at idling speed."

That is just info. I don't think it is your problem.

Ok, cheers for that, just the type of answer i was looking for! I understand now
I wonder why someone would remove that fuse

My guess is the intake air temperature (IAT) sensor located near the throttle body as shown here:

I had already tested this at 20oC and found to be about 500ohms, so good according to data i have read?

Think i will test the MAF next as already suggested by s2central. I have cleaned it but no difference. i have been reading a few posts and it seems common.....

Dan

[Audi-Porsche Avant RS2]

Hello, sorry, where can I find the test for try the engine sensor? Thanks a lot! Bye

Alessio

[bigdan]

Right, thought i'd wrap this one up!!

I finally broke down and tested my WGFV, found it measured 337 ohms at ambient temperature!! Thanks to this forum i read somewhere that it should be between 25 and 35 ohms!

Recieved my new WGFV from the local stealers yesterday (£48), fitted it last night.....

All sorted and driving just like an s2 should!!!