New S2 Avant Nothelle N300 owner

[Ian Simmonds]

Only through N75.
ECU modulates N75, reducing pressure applied to the bottom chamber of the wastegate.
In limp mode the N75 is left open to the wastegate which will open at spring pressure.
If you were to disconnect the hose from the WG (and plug it). The WG would stay closed and the car would overboost till the fuel is cut.

Have you checked that your ECU is seeing boost pressure? It’s been known for the boost/vac line from the inlet manifold to leak or be disconnected at the moisture trap under the carpet on the uk passenger side.
The small cotton covered vac lines at the back of the inlet manifold are usually leaky if still original.

John, see this thread..

https://www.s2forum.com/forum/member-s-area/member-s-cars/60975-giving-the-s2-some-love/page13

You utter star!

[Tractor Dave]

Well done fixing yours. All my vac pipes are new. I'm still looking for my bug

[Ian Simmonds]

Well done fixing yours. All my vac pipes are new. I'm still looking for my bug

I followed this -

https://forums.quattroworld.com/s4s6/msgs/20987.phtml

and in particular the vacuum schematics on page 6

[Tractor Dave]

I did some maf testing today following UrS4boy’s helpful guide. All the numbers are good and everything seems ok. I cleaned the connectors again for good measure.
I also replaced the last bits of old vac pipe left. These were the short lengths next to the ecu.
I will do another boost leak test again tomorrow.



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[Tractor Dave]

Took the S2 for a little spin to visit Newsh today.


We did some tests (two heads is better than one) and after a bit of head scratching and a small sprinkle of Newsh fairy dust, I think we are on to it. It looks like my nice new Bosch fuel pump might be a fake.


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[Tractor Dave]

This describes my drive home exactly
https://www.s2forum.com/forum/techni...of-a-fuel-pump

I bought the pump from KMS on ebay and have sent them a message

[Greg_S]

good luck getting this sorted, might be worth looking at the walbro pump instead

[Tractor Dave]

good luck getting this sorted, might be worth looking at the walbro pump instead

I was looking at that Walbro post earlier but just bought a RS2 pump from Tango

[cultcars]

Awesome project! Love the color.

[Error404]

My (long!) process of elimination included power and continuity checks to N75 and MFTS (connected or disconnected), Swapped N75 and ECU (to an N300 vice MTM) put standard spring back in wastegate and vacuum checked for leaks, temporary replaced N75 with a turbosmart boost control (eventually ending up with it wound all the way out), removed air con belt. Car has full set of Roose boost hoses and a rebuilt turbo (last year). Throughout all of this it resolutely won’t go above 0.7 bar of boost in any combination.

Wastegate sticking

[Error404]

Dave I haven’t forgotten about the terminals for the tank connector. Sorry I have been massively slammed. Will get them to you in the next few days

[Tractor Dave]

Dave I haven’t forgotten about the terminals for the tank connector. Sorry I have been massively slammed. Will get them to you in the next few days

Cheers Alex. Don't forget the locking tool

[Error404]

I won’t

[newsh]

Wastegate sticking

It was boost leaks from vac pipes including DV vac not connected

[Tractor Dave]

Thanks to Cardcrash I now have a RS2 pump and basket.
I drained the tank completely and some yuk came out.


The RS2 basket is almost identical to the S2. Just different neck.


Everything was given a good clean and put back together.

And, best of all

Boost is back! Hurray


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