I have boost issues :(

[Colin850]

I've just fitted a refurbed, ported and polished 16T with angled flange along with a 3" downpipe and ported ME7 manifold. Initially had some problems with the exhaust blowing round the turbo area but this is all fixed now.
Took her out for a good long test drive today and found that my boost wasn't holding properly. It would peak at around 9-10psi for a second or 2 and then drop to between 6-7psi and stay there.
I thought it would be the actuator wound to tight as this is what a lot of people say so i waited for her to cool down a little before checking it, it seemed ok but i did loosen it a couple of turns just to make sure. Took her out again and there was no change in the boosting, still exactly the same.
All the boost hoses have been upgraded to samco, also replaced the vacuum hoses from the BCS to the turbo/actuator/intake with upgraded fuel hose.
Where else could there possibly be a boost leak if any?
Any advice/help would be much appreciated

[claymore]

are you sure the vac pipe to the recirc valve is ok, or could the diaphram in the recirc valve be split?

[Colin850]

I use a dumpvalve and have a blanking plate where the recirc valve would be. Thanks anyway

[p fandango]

I use a dumpvalve and have a blanking plate where the recirc valve would be. Thanks anyway
is the dump valve set-up correctly, on some you can adjust the pressure or fit different strength springs so they work well with the engine

[claymore]

^^^^^^^^^^^beat me to it^^^^^^^^^^

ok, is the vac pipe to the dump valve good, still sounds like a big boost leak somewhere, so if all the boost pipes are ok then it might point to a split IC.

[Colin850]

is the dump valve set-up correctly, on some you can adjust the pressure or fit different strength springs so they work well with the engine

Its a forge dumpvalve, i do have the different springs so i can adjust it if needs be, but i was thinking that if it was the spring then surely it wouldn't let the boost reach 10psi in the first place, as soon as the boost went above the springs rate then it would open instantly.
I will try the next spring up tomorrow anyway to see if it makes any difference


^^^^^^^^^^^beat me to it^^^^^^^^^^

ok, is the vac pipe to the dump valve good, still sounds like a big boost leak somewhere, so if all the boost pipes are ok then it might point to a split IC.

Yea the vac pipe to dumpvalve is ok, that was also replaced with the others.
Is there anyway of checking the IC for splits? I've heard they are a right pain to get out so i wouldn't want to change it to find out there's nothing wrong with it.

[claymore]

I would be inclined to take the dump valve off all together to take it out of the equasion. if it boosts ok without a DV, then thats your problem, if it still doesnt boost properly, then you should pressure test the IC

[Colin850]

Thats a good idea, although having the samco hoses means i'l have to find a bung of the right size to fill the hole where the dumpvalve would be.

How would i get the IC pressure tested? I guess i'd need to take it to a garage for that?

[claymore]

How would i get the IC pressure tested? I guess i'd need to take it to a garage for that?

when I tested mine, I blanked off the bottom boost pipe and cobbled a fitting onto the top, and used a 12v tyre inflator to just pressure it up youll soon see if it doesnt hold pressure.,

[Colin850]

Ok i'll give that a go tomorrow.
Thanks for your help

[claymore]

Let us know how you get on.

[cragmaz]

I would be inclined to take the dump valve off all together to take it out of the equasion. if it boosts ok without a DV, then thats your problem, if it still doesnt boost properly, then you should pressure test the IC

yep, ill second that!

you dont really need a DV anyway, unless you want the noise. they seem to cause a lot of problems, the factory re-circ is spot on.

As for the boost problem, did it boost ok before you took the turbo off for the rebuild?

Craig

[Colin850]

yep, ill second that!

you dont really need a DV anyway, unless you want the noise. they seem to cause a lot of problems, the factory re-circ is spot on.

As for the boost problem, did it boost ok before you took the turbo off for the rebuild?

Craig

Its not the original turbo, i replaced my old 15g as the seals had gone and it was burning a lot of oil. I went for the 16T cos i wanted a turbo with an angled flange as i'd bought a 3" downpipe for it.

Yes the dumpvalve is purely for the noise :smile:

[Dangerous Dave]

I had this probem after I refurbed my turbo (its the smaller 13G turbo). It would reach 10psi and drop down to around 7psi. I tried lots of things, pressure tested the system from the turbo inlet side and found leaks on the injector seals. Fitted new seals, but that didn't work. Tried a second refurb kit but that didn't work either. I tried adjusting the actuator rod, but that didn't work. Recently I bought a 16T turbo, and I fitted the wastegate actuator off it to my 13G and its worked, now boosting to 12psi and holding there. (One note though, the 13G turbo has a weaker actuator spring anyway, but I thing I might have damaged it when I did the refurb)

Maybe worth trying the actuator off the 15G to rule it out (although I think the 15G has a weaker spring than the 16T, but I still maybe worth trying).

[Colin850]

I had this probem after I refurbed my turbo (its the smaller 13G turbo). It would reach 10psi and drop down to around 7psi. I tried lots of things, pressure tested the system from the turbo inlet side and found leaks on the injector seals. Fitted new seals, but that didn't work. Tried a second refurb kit but that didn't work either. I tried adjusting the actuator rod, but that didn't work. Recently I bought a 16T turbo, and I fitted the wastegate actuator off it to my 13G and its worked, now boosting to 12psi and holding there. (One note though, the 13G turbo has a weaker actuator spring anyway, but I thing I might have damaged it when I did the refurb)

Maybe worth trying the actuator off the 15G to rule it out (although I think the 15G has a weaker spring than the 16T, but I still maybe worth trying).

I had thought it could be the actuator being faulty as the rod didn't feel as sturdy as the one from the 15g, but after explaining this to a friend he claimed that an actuator would either work or it wouldn't and that it couldn't be that, then again he might just have been talking sh*t.
I will try the other actuator tomorrow and see how i get on.
Thanks for your advice

[cragmaz]

BCS maybe???

Try a bleed valve on it to see if it will increase boost pressure.

if no, then you need a friendly dyno to get it diagnosed properly, could be all manor of things!

Craig

[Colin850]

BCS maybe???

Try a bleed valve on it to see if it will increase boost pressure.

if no, then you need a friendly dyno to get it diagnosed properly, could be all manor of things!

Craig

How would i connect the bleed valve up?
Would it go on the vacuum pipe between the BCS and the actuator?
Or would it be connected up using all 3 pipes as if it was the BCS?
Thanks
Colin

[Dangerous Dave]

I wouldn't use a bleed valve, I'd use an manual boost control valve instead. The MBC (or bleed valve) fits between the pressure side of the turbo and the wastegate actuator. When the pressure reaches a level set by the valve, the wastegate is opened. The MBC can also fit in the line between the BCS and the actuator, but then there is reduced control of boost spikes.

The BCS is a just an electronic bleed valve really, the air bled off is just returned to the intake instead of being leaked to the atmosphere.

[Colin850]

I wouldn't use a bleed valve, I'd use an manual boost control valve instead. The MBC (or bleed valve) fits between the pressure side of the turbo and the wastegate actuator. When the pressure reaches a level set by the valve, the wastegate is opened. The MBC can also fit in the line between the BCS and the actuator, but then there is reduced control of boost spikes.

The BCS is a just an electronic bleed valve really, the air bled off is just returned to the intake instead of being leaked to the atmosphere.

Ok, thanks, i will look at getting an MBC instead then.
I did try my actuator off the 15g like you suggested in a previous post but this did nothing, still exactly the same.