[Mk2] [Turbo] Rev3 Turbo not boosting

[shinny]

I can hear a noise like a vacumm cleaner, but I assumed it was the air filter induction noise.

To some extent that's normal induction sound on a turbo. But an open BOV might cause that sound to be louder?

I've got a HKS blow off valve. I sprayed it with leak detector when I was inspecting all the joins on the inlet pipes and it spat some of the fluid out when I was moving the throttle cable.

You would expect the BOV to release a little air when you come off the throttle, even when you're revving the engine in neutral. However if it's letting air out when you're on throttle then you have your culprit!

If you've got long enough arms, you could put your hand infront of the BOV to feel if there's air coming out on throttle or not.

[rob6539]

Where are you based? Happy to have a look if you like- I'm near Newent

That’s very kind of you! I’m up near Tewkesbury. If I’m still stuck after this weekend of tinkering I may well take you up on that. Thank you

I've got a HKS blow off valve. I sprayed it with leak detector when I was inspecting all the joins on the inlet pipes and it spat some of the fluid out when I was moving the throttle cable.

You would expect the BOV to release a little air when you come off the throttle, even when you're revving the engine in neutral. However if it's letting air out when you're on throttle then you have your culprit!

If you've got long enough arms, you could put your hand infront of the BOV to feel if there's air coming out on throttle or not.[/quote]

I’ll have a look after work and see how it goes.

Thanks guys

[rob6539]

Boost has been achieved!

I've got a berk intercooler and the inlet pipe at the bottom had decided to pop off. Feeling a bit of a berk myself as I should have noticed that, but was too busy fearing the worst.

Big thanks to all you guys who helped and offered your advice; it is greatly appreciated!

At the moment though, I'm only getting about 7psi of boost and this was after the car was nicely warmed up. Should I be expecting more around 12psi?

[Slarty]

a hose completely off between the outlet of the compressor and the throttle body.

I've got a berk intercooler and the inlet pipe at the bottom had decided to pop off

Glad it was a simple, cost free fix though

As for 7psi, which revision is the car?

[rob6539]

Yeah your bragging rights have been well earned

It's a rev3

[Slarty]

lol, not bragging in the slightest, glad that you've found the leak

Ok yeah, 7 psi is low for a rev3. Do you have a boost controller of any sort? If not, I'd carry on checking around for leaks, if there's one, there might be another.

If you have a boost controller (mechanical or electronic) try temporarily bypassing it to see what you get.

[madmr2man]

Where are you based? Happy to have a look if you like- I'm near Newent

Seconded, I'm in Gloucester to!

Glad you found the issue, if you have any more problems, I'll be happy to come and have a nosy!

[rob6539]

Seconded, I'm in Gloucester to!

Glad you found the issue, if you have any more problems, I'll be happy to come and have a nosy!

That's very good of you, thank you.

Ok yeah, 7 psi is low for a rev3. Do you have a boost controller of any sort? If not, I'd carry on checking around for leaks, if there's one, there might be another.

If you have a boost controller (mechanical or electronic) try temporarily bypassing it to see what you get.

No I don't have a boost controller; I'll have another look at the hoses for leaks; but I've already taken the hoses off (from turbo to throttle body) off once when I found the intercooler pipe wasn't attached. Will check the blow off valve as well.

Is it worth looking at the turbo VSV? I've read previously that the actuator will mechanically open the waste gate at 7psi, but it's the VSV that will bleed some pressure off so the waste gate opens at around 12psi? Saying that, I've also read conflicting info!

[Slarty]

It's certainly worth checking that the VSV is plugged in. If a previous owner had a boost controller of any sort, they may have unplugged it to stabilise the boost to allow the controller to work correctly.

From memory it's under the intake manifold.

[rob6539]

Yeah the turbo vsv is plugged in.

What would be the best way to go about testing it's still operational? Take it off the manifold and pass 12v though it and see if it switches?

[Slarty]

The simplest solution is to unplug the VSV, put an MBC in and see what's what.

From what I can remember, the VSV's in rev3's+ work more like an EBC in that they bleed off a variable amount of boost depending on circumstances etc, so I'm not sure if they work off 12v or 5v. Might be worth Pm'ing one of the affiliates and seeing if they know...?