What else cause 0.4-0.5 bar max boost

[shone190]

I also checked the fuse and PIN 1 (with LED) on N75 connector, and LED is on when I turn the ignition.

[shone190]

As I know, MFTS is limited boost factor only on 3B engine, correct me if I'm wrong?!?!

[UrS4boy]

As I know, MFTS is limited boost factor only on 3B engine, correct me if I'm wrong?!?!

Also ABY and ADU there is an ECU/MFTS connection, but NOT so much with the AAN. Click on the link below and then on the MFTS live link label on the right side of the diagram (the other labels are also live links):

http://members.shaw.ca/speedtek/UrS%20Engine%20Bay%20Device%20Map.html

[shone190]

So it's possible that PIN46 is connected to MFTS and if it's bad sensor, I can't reach max boost?

Is there a way to just unplug MFTS and get max boost if it's a reason for limit?

[shone190]

One more question, if I have ABY loom and AAN ECU, is there a possibility that bad MFTS cause this?

[shone190]

I just tried to unplug MFTS, drive the car and everything is the same

[UrS4boy]

One more question, if I have ABY loom and AAN ECU, is there a possibility that bad MFTS cause this?

Oh, *now* you tell us. ABY and AAN ECU pin-outs are NOT exactly the same.

You need to visit S2Central.net and find the RS2 (ADU) wiring diagrams, including this one: http://s2central.net/main_frame.html

[shone190]

No, I didn't say that I had ABY loom, I assumed that

As I say, I just tried to unplug MFTS and drive the car, everything is the same, boost 0.4b

[UrS4boy]

No, I didn't say that I had ABY loom, I assumed that

You might want to provide us with the correct facts, i.e. which loom, etc. before we continue to try to help you.

All I can tell from the info so far is you have no proof that the wiring between the WGFV and the AAN ECU has continuity and/or is connected to the correct pin. You should at least confirm these.

[shone190]

OK, I'll check all of that but as I told, everything was OK and worked OK until a few months ago

[Jamo]

Assumption is the mother of all....,
I do diagnostics for a living and the very 1st thing you learn is just because it worked in the past doesn't make it right
It's back to basics sir recheck everything from the ground up and if you have access to another ecu try a swap

[UrS4boy]

Assumption is the mother of all....

Mistakes. "But I thought...."

[shone190]

Boost test kit came and there is no boost leak in system. So I really don't know what else to do

I tried to change from other car (URS4) which boost 1b as it should be:

1. N75
2. Dump valve
3. ECU
4. MAF
5. Changed all vacuum hoses with brand new
6. Moisture trap
7. New turbo hose from Maf to turbo
8. TPS
9. No boost leak
10. disconnect MFTS

This is really nightmare

Does anybody know what else should be the reason for this?


@UrS4boy
ECU pinouts for AAN and ABY are the same:

http://forums.quattroworld.com/s4s6/msgs/21009.phtml

http://s2central.net/main_frame.html

[bartolomeus]

I'm having the same problem.
I've checked all the things above and still nothing.
Going to check out the oil breather check valve if it's broken or not.

[UrS4boy]

I'm having the same problem. I've checked all the things above and still nothing. Going to check out the oil breather check valve if it's broken or not.

While I personally recommend isolating the boost hoses between the turbo outlet and the throttle body, including disconnecting and pluggin the ISV hose, the breather hose going to the MAF to turbo hose and the BPV hose, there is merit in just pressurizing at the turbo outlet hose. That way, leaks at the ISV or in the PCV system will also show up, e.g. a split in the boot that houses the one-way bleeder valve.

This could be your and/or shone190's issue.