How much boost should I be seeing?

[K7ERG]

What about a weak wastegate spring?

Craig

[dest]

I think there is big confusion here...

My information was on the WGFV - that is the 'N75' valve... The solenoidy-looking thing with an electrical plug that is attached to the MAF hose.

I suspect the valve you have turned round, by reference to the 'vacuum hose' is the throttle bypass valve (TBV).

The expression D'oh springs to mind.

Check the TBV isn't leaking, and that WGFV is correctly fitted - renew it if its not a recent one. Other than that, it will be an air leak from a split/loose hose.

Worst case a holed intercooler.

A leak-test is required...

LOL of course you are correct
No idea what I had in my head then!
Yes, it was the TBV I turned round.
That was replaced with a brand new one (710N revision) about 3 months ago, the N75 was brand new about 5 months ago too.

The intercooler was replaced 6 months ago due to having a leak, and has had various leak tests since, none of which showed any leaks.

The inlet pipe to throttle body hose was replaced with a silicon one due to splitting from old age, and also has the MarkH mod done too.

Tomorrow I will be ordering the remaining 3 main boost hoses so everything has been updated.

[andrewd]

Have you checked the microbore hoses around the back of the inlet manifold that lead to the ECU (and elsewhere)?

I checked mine at the weekend to find that they were very loosely attached and obviously leaking. Having tightened them up, the ECU and the LCD boost gauge is now seeing a higher (0.1 - 0.2 bar extra) max boost pressure figure. Low to mid-range pickup is much improved too.

[S2central.net]

It is definitely worth checking all that braided narrow tubing... It degrades with age.

Even without a MityVac tester you can test this stuff pretty well...

Disconnect each narrow tube from where it attaches to the IM and just suck on it with your gob - it must be airtight. Wrap the end of the hose in your mouth with tape or whatever.

DOn't forget the narrow hose at front of IM - that connects to the TBV and I've seen those fray thru more than once.

Oh and drive it with the WGFV connector OFF - you should see 0.4boost max - thats a quick sanity check for your WG.

Oh check that all your coils are tight enough too - do NOT overtighten them... Just be aware that loose ones make for a leaky cylinder.

Good luck - I'm sure you'll find it.

Paul