Project: RS2 ABY

[Sonic]

We boost checked this a couple of times and every joint was sealed, we tested the injectors also, and there appeared to be no leak.

We were able to get up to ~9psi measured from the inlet manifold after about 20-30s of 1.5bar air - after we stopped this the pressure would slowly decrease.

If there is a remaining leak i can't find it - and it's very small, and certainly not on the inlet. This does not explain the severe problems im having surely, and either way, doesn't explain why im getting 11 AFR at WOT in 6th with 1500rpm... i.e no boost.

If i drive the cat at ~75% throttle it's fine - it will hold 1 bar and take off like a scalded cat as it should. The moment i give it WOT, it will spike at 1.5 bar and the AFR dives, which seems to kill the power and boost.

Why is the exhaust valves not correct? Surely pressure will not be held through the block as at least one of the exhaust valves will be open meaning air escapes through the exhaust? I thought the idea of a boost-leak check was to block off the throttle body and MAF hoses, and check there are no leaks in the inlet, not check everything from the airbox through to the exhaust and there is no way everything there will hold pressure.

Cheers for the help - but im not sure where to go with this now or what to do, as i cannot find any boost leaks with it

[A80Avant]

i had similar problems when i tried to do a boost leak test a few years back. Eventually i took all boost pipes apart and tested them separately with bungs and then checked the vaccum hoses separately. Everytime i did the usual procedure as to test the whole engine, i ended up not being able to pressurise the system at all.

[Rusty]

Leaking exhaust manifold / joint perhaps? Basically a boost leak on the exhaust side pre turbo?

[4WheelDrifter]

Is the breather check valve ok?

[AndyP]

I'd blank off the PCV system, breaking the system down into smaller parts makes it easier to find leaks.

http://www.s2forum.com/forum/showpos...0&postcount=11

[Sonic]

Yeah i have one of those Andy, also im running the reverse inlet manifold so not sure i the blanking player for the throttle body hose will work.. need to give it a go when i get my testing kit back.

[newsh]

You must disconnect the breather connection at the MAF hose or the check valve in the breather system is not tested (it will have pressure on both sides) Also crankcase is presurised and oil cap will start to vent at a certain point..

Similar situation with the DV when pressure testing via the MAF hose, its pressurised both sides so a leaky diaphragm will not show, You need to test DV by pulling the small hose from the IM and making sure you can get a vacuum on it. Mighty vac is good or suck it and see

9 PSI is not going to tell you much when your target boost is 30PSI. Use the bungs and pressure the inlet tract. The TB is the same size still so the bung should still work

[4WheelDrifter]

Yes. Suck and see is pretty easy on a DV.

[andy10v]

9 PSI is not going to tell you much when your target boost is 30PSI. Use the bungs and pressure the inlet tract.

I couldn't even hear my boost leaks at that pressure, I tested intake alone at 1.5-2 bar, just make sure the bungs are clamped down properly!

[Sonic]

Just to confirm - we had the catch-tank return hose disconnected from the MAF hose, with the MAF hose bunged.

I was pressuring the system with 1.5 bar, and we did hear/see some leaks which are now fixed, but regardless we are still only seeing 4-5psi pressure in the inlet manifold, slowly climbing up till about 9psi.

I would have expected a leak of this size the be pissing out air and not the kind of thing you could miss, so the exhaust is the only thing i can think of.

[Ross]

Just to confirm... the MAF breather hose was bunged. Soapy water was sprayed on all the intake joins, we found they were pretty much all leaking and those were tightened up. Admittedly not tested to huge pressures but there were no bubbles after we were done; the intake was tight up to the IM. The ISV has been deleted from the breather system as Andy's set up is a twin tank set-up with return to sump, and no return to the IM. As far as air hoses go it's a pretty simple set-up but it is still not holding pressure.

I am still confident to say there is no leak on the intake tract that could cause these problems. Simply put we tested it about 8-10 times until it was leak free. Good point on the DV though, that could do with pulling out and testing / swapping when the WGFV is tested. No leaking on the injectors either but didn't test for anything leaking out of the IM... should have sprayed the whole thing down!

It still feels like it's clutching at straws, there has to be something off to cause it not to pressurise - thinking about how well mine held 1.5-2.0bar of boost it concerns me that the breather system was getting so much pressure. I'm certain it was being pressurised from the block breather as well... what's involved in getting a compression test done??

[andy10v]

By bad, I read that wrong

Compression test involves sticking a compression tester in the spark plug hole and crank over, can stick oil in the bores to seal the rings a bit to see if that makes a difference.

[Error404]

better to do a leakdown test, can give you far more clues if something untoward is discovered

[Sonic]

Anywhere i can get this done before saturday?

[Rusty]

Sorry if this has been mentioned but I'm too lazy to re-read it all.

dump valve? This sounds like it could be the only thing left.

Make sure that you fit a known working one and it's the correct way araound and has the pressure line to the top of it!

Other thing was the breather system connection to the N80 pipework (mentioned above). The 1-way valve is rather important, as it stops all your boost peeing out of the 8mm connection!