166bhp S2 Avant....help!

[Heat Seeking Missile]

Right, as some of you know, the rolling road day highlighted a serious problem with my S2.

It was diagnosed as running dangerously lean, they only ran it once too. Luckily, Animal Mother, S-Express and the bloke with the 321bhp S2 had a quick look round and gave it a go on the VAGCOM (cheers) and it appears to be running on only mechanically controlled boost, thus indicating I have a leak somewhere or the recirculating valve or that brown thing (I cant remember the name of it) have failed. I've done a few things to it today, such as replacing manky little hoses and a few test runs with a crudely plumbed in boost gauge.

I tapped into both ends of the inlet manifold for the gauge and got the same reading at both points, which was 0.4bar, the boost climbed nicely and quickly to 0.4 but wouldn't go any more, if I remember rightly, it should be about 1.2bar shouldn't it?

I've got a few pics to be uploaded but I need to restart the computer.

Now please bear in mind, this is the first turbo'd car I've had thats gone wrong, so I dont exactly 100% know what I'm doing so be gentle

Mark

[dest]

I would be very careful about giving it full boost if its running lean!!

[Jon441cc]

Brown thingy (wastegate frequency valve)


search under S2 then engine.

https://sslrelay.com/s74326199.oneandoneshop.co.uk/sess/utn;jsessionid=154749b9de2d837/shopdata/index.shopscript

[A80Avant]

if the N75 valve(WGFV) mentioned above was gone,it would have appeared on the VAGCOM.But that is not always true as it may leak and still appear ok.You should change that and run a leak test.
Going only to 0.4bar is the safe mode of the car.

[Heat Seeking Missile]

Brown thingy (wastegate frequency valve)

Thats the one! I couldn't remember it

if the N75 valve(WGFV) mentioned above was gone,it would have appeared on the VAGCOM.But that is not always true as it may leak and still appear ok.You should change that and run a leak test.
Going only to 0.4bar is the safe mode of the car.

The only thing that came up on VAGCOM that was remotely relevant was blink code 516, something to do with the throttle position.

S-Express has kindly offered me the loan of a spare N75 valve, so I'm going to stick that on, and see what happens.

Here are some pics I got from today.

Rigged up boost gauge:


First location of tapping the gauge in, not the best but gave the same result as the back of the manifold (which I forgot to take a picture of):


Dyno print outs:



Mark

[S-Express]

Mark, If you're going to install a boost gauge permanently, then tap into the pipe going into the ecu - that way you don't have to find a hole in the firewall to stick the pipe through.

[newsh]

See thats the right shape for the torque curve, just a bit low Nice and smooth, no misfires or wheelspin, just need to get your WGFV to work..
Have a good look at the PCV system, if its running lean on boost that meands there may be a leak before the turbo. If the leak was after the turbo it would end up being rich.

[ericd]

I've recently looked at a few cars (at various meets with others) where either the wgfv was dead or the wiring to it had been butchered/disabled.

Dead,broken or diabled wgfv don't throw up errors on vag-com, easiest way to verify
it's operation is to run the output test within vag-com , where one of the tests will specifically trigger the wgfv, (you'll hear it clicking), if it doesn't click then you can work back from the wiring to the wgfv, or connect another wgfv and rerun the test
shouldn't take more than a few mins to verify functionality.

If somebody has specifically disabled the use of the wgfv , usually inconjunction with some obvious modification to the wastegate spring setup, this will take a wee bit longer to diagnose , but hopefully you don't have this scenario.

HTH

[AndyP]

If your getting a 516 code on the VAG-COM then the TPS ( throttle position sensor ) is shot and this will cause it to run lean. Do a search, I seam to remeber Lou ( 220bhp ) had the same problem and changing the TPS cured it.

Andy

See here:-

http://www.s2forum.com/forum/showthread.php?t=17795

[Heat Seeking Missile]

See thats the right shape for the torque curve, just a bit low Nice and smooth, no misfires or wheelspin, just need to get your WGFV to work..
Have a good look at the PCV system, if its running lean on boost that meands there may be a leak before the turbo. If the leak was after the turbo it would end up being rich.

Its always felt like its been running fine since I've had it, no misfiring, no poor fuel economy or anything that would suggest such a severe drop in power. I went from a high revving N/A with 119bhp to what I thought was 230bhp and it felt a fair bit quicker so I never realised that much was wrong with it

Whats a PCV system?

Mark, If you're going to install a boost gauge permanently, then tap into the pipe going into the ecu - that way you don't have to find a hole in the firewall to stick the pipe through.

I think you mentioned that on Saturday and I forgot about it. Passenger footwell you said wasn't it?

Mark

[S-Express]

He definitely does have a problem with the throttle butterfly, when I operated it by hand it was a stiff as.....(trying to come up with a rude similie, but failing) something very stiff????

[S-Express]

I think you mentioned that on Saturday and I forgot about it. Passenger footwell you said wasn't it?

Mark

Yes, that's right.

I've found the dump valve and wgfv now so need to arrange collection.
You can either come to mine, or I'll give them to Rob and you can collect from his house in Brymbo. let me know by pm.
Cheers
Alex

[Animal Mother]

These are the codes that he got on the day.

My personal pick would be a vac pipe from/on the IM issue.

[S-Express]

Mark - from this, first things to do are free off the throttle so that it goes back to idle (i.e. makes that click sound as it stops - like I showed you) and you try my wgfv and dump valve.

easy peasy guide to extra 70 bhp!!!

[GazzaG60]

check the throttle cable isn't overtightened. this was a common thing on the vw's once the cable had stretched peopel used to overtighten them.

if its still not sorted i can lend oyu a maf and a diverter if you need them and a n75 as i dont use any of these with the vems. let me know and ill bring them when next at the rollers in a couple of weeks. maybe a good place to prove the problem too.