Newsh's S2 Avant!

[AndyP]

No codes with engine running.

With WGFV unplugged I get about 6 PSI which is correct. Car is boosting to around 20 PSI this morning no issues although boost is slow to build, without the push in the back that I'm used to with a chipped K24.
Are you aware of any ecu condition which would reduce the boost by about half?
The reduced boost happens after a hard run through 2-3-4, next time you put your foot down only 10psi, but then if you cruise and wait a bit its ok.
I wonder if its the cats? Johnnybravo has sent me 2 empty cats with the Milltek so we'll see how it goes with that.

You have PM

[GazzaG60]

poor fuel. engine detecting knock.

[newsh]

poor fuel. engine detecting knock.

Its weird though, I get one run up through the gears, coast back down, try again reduced boost. Cruise for a couple of minutes, try again ok.

[newsh]

Swapped back to the stock ecu, all seemed ok for a while but then it did it, really slow to boost up and only 10psi. Watching the gauge, it seems to boost a bit high sometimes too, nearly 19psi once so I've changed the WGFV for the one off the coupe, will see how it goes. When it behaves itself its going nicely.

Otherwise all's well, cambelt is changed, the key in the lower pulley was scarily fooked, about to break off so really glad its done
Milltek is fitted and sounds nice

[newsh]

A bit of progress on the Avant in the last week or so. I'd had some clearance problems with the Miltek back box, the system (being stainless) expands so much when hot it was touching and trimming the lower edge of the bumper with a hacksaw blade :redface: didn't fix it, once the bumper was cleared it just kept on going till it hit metal! doh! So I loosened the 2 connections in the middle of the car and tried to slide the rear section a bit further onto the front section, so to speak. No go at first as it all seemed so tight and I didn't want to start hammering etc and damage the system. Then I had a bit of a bright idea, I used a length of 1" webbing around the back box and the rear drive shaft and made a sort of spanish windlass to put some tension forwards. Back to the middle of the car and reaching under and wobbling the pipework the 2 halves of the system started to telescope together and I got another inch of clearance at the back, all good and now the system can get really hot without touching the rear of the car and making nasty banging noises.
Secondly the running issues I've been having had got slightly worse with the car doing a fuel pump cutout if I floored it at low rpms and the boost came up around 18psi.. I was thinking as I said before that this was to do with boost but I'd also noticed that there were fumes getting into the car when the windows were down and my passengers were complaining too. So I started to suspect something mixture related, either Lamda or MAF. A wiggle of the relevant connectors seemed to improve the fumes issue so I decided to do a proper job on the MAF connector with the DeOxit and some very fine worn out 2000 grit wet and dry which I keep for the purpose. The result is that the car is running better than ever, doesn't cut out, doesn't fill the cabin with fumes, picks up and goes more briskly and revs out more cleanly. Finally it seems like its running as it should. The strange thing is that it was never really bad enough to think that there was a particular fault, there must have been just enough resistance in the MAF contacts to mislead the ECU into less than optimum running without failing completely.
So.. Unbelievably.. it was that pesky MAF connector again!

[Acidburn]

sounds like you need to put the coupe engine in to help with this problem

[martinjs]

sounds like you need to put the coupe engine in to help with this problem

You mean put this in the garage and get the coupe out

[newsh]

Brilliant, all my threads have become Coupe vs Avant wars

[newsh]

Replaced the plug boots today and changed the rear knock sensor, also found a small boost leak where the boost tube joins the TB hose. The car is now flying but still drops to half boost if I give it WOT. I'm on the Homefried ECU again and seeing about 21-22psi max. Think I might try the adjustable WG cap from the coupe and turn it down to a max of say 20psi and see if its ok like that.
Haven't got a front knock sensor to try yet.
Still no codes and all measuring blocks look to be reading ok.

[newsh]

Have just tried a spare wastegate cap with the perch about 6mm higher which brought the max boost down a few psi. I really thought it'd fixed it as I was able to drive WOT though the gears a few times with no boost reduction, all was good for 15mins or so and then it did it


Still it feels like I'm on to something. I wonder if it can be heat related..

[LHD_Kid]

Still it feels like I'm on to something. I wonder if it can be heat related..

My money is on the front knock sensor....

Chris

[newsh]

Cut a window in the plastic which allows me to get a long extension and a torque wrench on the front sensor. It wasn't loose. Just need a new sensor to try now.

[DamianURS4]

necessity is the mother of invention....

[newsh]

The lower part had already been removed, probably for a thermostat..

[newsh]

I've changed the front knock sensor and sadly its still the same

Any sustained period of full throttle and high revs brings about a reduction in boost, a couple of minutes of gentle driving and its fine again.