0,4 boost, first run with the car

[Lopez90]

Yeah, i have measured resistance aswell, but i see its discussed before on the forum about resistance vs voltage.

As the pdf says:
Across Pins 2 and 3 on the switch: Throttle closed = 750 to 1300 ohms As throttle is opened from closed to WOT = increase to 3600 ohms If NO, replace sensor.

Mine goes to 3100 ohm at WOT, so i guess i would need to replace it?

Bit confused after reading this threat:
https://www.s2forum.com/forum/techni...ps-measurement

Some say measure voltage

[tekstil]

Can't give you pointers on that as I don't have first hand experience with it, I just added link with additional info you might need, while you were measuring TPS.
Most probably this isn't causing your limp home mode. Is the N75 piping around intake boot and wastegate area routed properly?

[Lopez90]

Long leg into turbo intake hose, leg pointing downward to turbo, last one to WG

[Lopez90]

Straight after i posted i went to the garage to double check.

I even changed the N75 and still didnt see it. My leak test was from turbo and not from the MAF, so a leak test from MAF would have catched this one.

Need to go to bed now but eager to fix and see if it boosts as it should after the fix

[Lopez90]

Ok. Still got trouble with boost. Only get 0.5ish bar.

So far i have done:
- Changed ECU
- Changed Turbo
- Changed the back knock sensor (green)
- Tried with another MAF
- Tried with another N75
- Swapped catalytic converters
- Changed and checked timing belt
- Changed fuel pump

I'm gonna do another boost leak test and change the front knock sensor.

Anything else i havent done that can cause this?

I'm soon gonna have nightsmares of this issue

[Tractor Dave]

Fuel filter and pipes all good? Have you done a flow test?

[Lopez90]

Forgot to mention new fuel filter. The car has been to a tuner. Ran rich before new fuel pump, so i can assume everything is fine yea. Dynotested to around 200hp

[Tractor Dave]

Was it boosting well before it went to the tuner? Have you checked the engine is timed correctly?

[Lopez90]

Ran very rough before it went to the tuner. Runs «smooth» now, just wont boost above 0,5bar. He has changed the timingbelt and doublechecked timing.

Bought the car as a project so it hasnt run anything above 0.5 since i have owned it.

[Tractor Dave]

Very strange one. If you are not getting sudden boost cut it not likely the ecu cutting boost so something physical. Is the exhaust blocked? Cats breaking up?

[Lopez90]

Had a pair of extra cats so i changed them aswell with no luck. Got New cat-back exhaust. I’m starting to doubt myself that the exhaust was filled with something when shipping and i havent taken it out

[Ian Simmonds]

I spent years chasing to get ours to go over 0.9 bar into over-boost. Changed most things on your list. In desperation I even removed N75 and fitted a turbo-smart manual boost controller. With that set up, it still only made 0.9 bar, regardless as to whether the turbo-smart was half wound down, or fully wound down. As Dave says, it just had to be something physical. So, in desperation I bought a full Roose silicone boost hose kit, replaced all the small lines as well and went back to the N75. Fixed… By that stage, I’d probably run 3-years under boosting. I honestly think the original hoses were all collectively failing together, almost becoming porous to boost, so testing sections didn’t give an accurate reading of the collective loss.

[tekstil]

Still using stock ECU with chip? Do you know what kind of software is in it (for stock car or with modified hardware)? As you said it runs smooth now after visiting tuner, so did he do some adjustments to stock ECU or just ran dyno to get the numbers?
Also you never mentioned checking wiring to N75, only changing physical solenoids, maybe your ECU isn't controlling it at all and sees it as disconnected.

[Lopez90]

Yes. The tuner changed timing belt, fuel filter and pump. Not quiet sure What he has adjusted since the car was at his shop for 4 months.

not sure What kind of software but the ecu was tested before i bought it on another 3b. Same with the other ecu i tested. N75 clicks when using output test with vagcom. Tuner has checked the wiring aswell

[newsh]

0.5 bar sounds like spring pressure, ie in limp mode, ECU not controlling boost.

N75 clicks in output test, ok.

Check you're getting the N75 signal from the ECU at WOT. Easy way is, start the engine, put your fingers on the N75, blip the throttle quickly to WOT, you should feel the N75 clicking.

Disconnect the MFTS and see if you get boost.
Edit; just read the whole thread again and I see you did that in the first post, maybe try again anyway..