RS2 Boost Problems

[montyrs2]

Ah yes, then I am calling the WGFV a boost valve. That part is brand new. MAF is def on my list of could be broken. Is there anyway of testing it without either getting another one or having vag com etc. Is there a voltage output at idle etc I can test with multimeter.

Worth asking at this point, where is the best source to get vag com and needed wires from?

[A80Avant]

yes you can use a multimeter,do a search here as im not familiar with the correct voltage at idle but it has been discussed here

[newsh]

You can read the blink codes right now with a led or bulb, instructions on S2 Central.
Lots of us use the cheap leads from Alphabid on ebay and the old free version of vagcom, its fine for our cars. Plenty of threads on here about it

From my own experience, if the MAF goes you'll get a hard cut out like slamming into a wall, same if the MAF connector is dirty. Worth cleaning that connector though, if the connector is clean and working correctly the MAF cleans itself.

Have a look at the vac tube that connects to the ECU, undo, cut off half and inch of tube and re tighten, a leak here can lead to the symptoms you describe (incidentally this can read as an ECU fault! I hope you kept the old one..) . make sure none of the small bore hoses are loose round the back of the IM too, look for oily deposits as a telltale.

[veneto rs2]

that amount of revs it's corresponding to top boost level...
So if there's a boost leak it has to be small otherwise like others say you'll have a big cutout (hitting a wall it's the right comparison!)
If as you say have a bad idle i will check the idle valve pipes connections
on my RS2 i had a similar issue car was ok but it could not mantain the pressure also idle was bad specially when the motor was hot and AC was on.
This was ending often to have the motor switch off when approching i.e. a traffic light in summer.
I went on a dyno like that and the results were 296 bhp (car it's chipped with PKM eproms)
Problem was a small crack on the inside part of the lower pipe of the idle valve the one that goes downwards..... very hard to find
To sum that:
If you have a bad (low) idle it could be the valve that it's sucking air from outside
On the other end when you have pressure build up from the turbo you'll have a boost leak

Both things are not detectable by VAGCOM

Stefano

[Lloyd]

Hi there Monty, welcome to the forum mate.

I would definitely arrange a visit (perhaps drop in in person to book it) with MRC for a full health check. This will cost ya about £50 and will involve pressure testing as well as fault code checking. As they're not far from you and frankly excellent this is your cheapest and quickest path to solution. My £10 is on a boost leak. See if you can hear it when driving? check for a transverse split along the top of the throttle body hose.

Look forward to seeing your car sometime.

[Fat Audi 80]

I totally agree with Lloyd.

My tenner is on a boost leak and my other tenner is on the fact that Doug at MRC will fix it and you will have the best drive home ever!

Get it booked in.

to the forum.

Cheers,

Steve.

P.S. I am in Didcot, so if you ever want a meet up or a chat let me know....

[montyrs2]

Ok story so far.

I had a quick play with the car last night. I disconnected the idle control valve. There was an audible change in induction noise, a loss of a hissing noise and the idle speed increased from around 700 ish to between 900 and 1000, a bit more normal. I could'nt see or hear a leak in there, in response to veneto rs2's post, but hopefully I will get some time to take the pipes off etc and have a look. Fat Audi 80 do you have any pressure testing kit as you are even closer to me then MRC! I ran the car with the idle valve disconnected and it made no difference other then a much better idle at traffic lights etc.

Old ECU had a number of faults and was def broken but old one went back as exchange unit to vag spares.

[A80Avant]

if the isv is the issue it costs around 250euro(so around 200GBP i guess)...not a pretty sight.I had to buy a new one when i first bought the rs2 myself...

[Fat Audi 80]

Hi Monty,

No I don't I'm afraid. I only have a fault code reader that may be of use to you. I am still suspecting a boost leak.

Cheers,

Steve

[Al Wyn]

Monty pm me your details and i will lend you my boost tester buddy as the guys are saying it sounds like a boost leak somewhere...i also have a selection of hoses if you need them

[montyrs2]

Papvas, what where your symptoms before you changed your ISV?

looks like I have a boost tester on route and some plans to make one so will investigate and keep you posted.

All ideas still considered.

[A80Avant]

erratic idle,stall on every red light,and when i disconnected the ISV it was running better.
as the others said,look if the hose is split,clean the ISV with carb cleaner and WD40 retry and then decide to go for the ISV...cheaper!

[montyrs2]

Mine idles fine, it just idles low at around 600-700. When un plugged it idles much better at 900-1000. Either way its all coming off as soon as it stops raining!

[Al Wyn]

How did you get on with the boost testing?

[montyrs2]

Al cheers for the kit. Got it all plumbed in yesterday and hey presto my inlet system holds pressure like balloon with a hole in it! I filled it up with 30 psi and watched the gauge go down in front of me. With a held charge of 30psi I could indeed here large volumes of air leaking.

You actually beat me to it here as was going to post today with my findings.

So basically, I stripped all the pipes off and had a really good look at them and can't find anything that looks like a split or crack etc.Not the obvious easy fix result I may have hoped for.

I then loaded up the wastegate with said pressure and can hear it working and hear the large amounts of pressure leaking from it! I would expect the wastegate to hold pressure, am I right? So I took the wastegate top off and had a look at the diaphram in there, no signs of damage so I took the whole thing off and had a look. The valve in the wastgate fits into its guide like a pr%3k in a bucket. This is allowing any and all forms of air and pressure I guess to pass from the exhaust into the underside of my diaphram, explaining the thick layer of soot on the underneath of my diaphram. I've never had one of these apart but I cannot imagine for a minute that its intended for pressure to go from the exhaust manifold to the underside of diaphram.

In my thinking, then when closed the turbo boosts. But as soon as it opens to control boost the pressure can pass into the wastegate then into the underside of my diaprham cuasing it to open fully and hence dump all boost. It then takes a full lift off to drop pressure in exhaust and allow wastegate to close.

On my car if you accelerate to the point where the boost goes, then quickshift you don;t get any boost in the next gear. This all makes sense to me and what I know about turbos, but I could be barking up the wrong tree totally.

If my wastegate is at fault does anyone have any experience in rebuilding them, more precisely replacing the valve guides, but then also preloading the spring in the top etc.

Again thanks to Al for the boost test kit and thanks for everyones help.

PS sorry for any poor spelling i'm typing quickly at work so no one sees!!!!