Can't raise boost?

[codez]

Thats strange that it gave you less boost.. maybe its not a ball and spring lol..

Actually my BOV is leaking atm too.. adjust it to the tightest setting tape it up, block it off.. whatever.. JUST WIND THE BOOST DOWN lol..

if your BOV is venting to atmosphere it will cause you trouble with the AFM, youll back fire and splutter. hopefully its recirculated back into the intake..

its a steep learning curve i know.. youll get use to it and then you can pick on the noobs lol..

okay mate ill give that a try tomorrow, cheers

yeah my BOV's recirculated to the intake

[woggin]

you're wrong, if it's flow metered and you're losing 10psi then it will be running rich as a motherfucker

i know, i have already said that, aybe he just isnt picking up on t overfuelling, he is a noob dont forget

[codez]

no need for that.. I'm only 17 how much do you expect me to know

[the_random_hero]

Wastegate IMO.

[pauljones1976]

Second the wastegate. It's definitely worth checking the actuator. (I'm assuming you have an internal wastegate here)

The actuator has a diaphram inside. It is held in place with a spring and connected to the actuator rod which runs along to the wastegate flap on the exhaust side of the turbo. The diaphram is pushed toward the rear of the actuator when air pressure is applied to it. That air pressure comes from a feed from the compressed air side of the turbo. (it's easiest to think of it as a tiny little feed of 'boost'.)

The spring in the actuator also holds the wastegate flap closed. If it werent' for the tension in the spring, as soon as exhaust gas pushed on the flap it would open, allowing gas to escape rather than to spin the turbo.

The rod will only start moving when the air pressure from the compressor feed exceeds to force required to overcome the spring tension (ie: 7/8psi stock) so under normal circumstances you recieve 7-8psi.

When you bleed air with a manual boost controller you're just allowing some of the 'boost' in the feed line to the actuator escape, letting less air pressure (boost) into the actuator diaphram. In effect it is tricking the actuator into thinking the boost is lower.

The wastegate flap is constantly under pressure to open from exhaust gas pushing on it as it rushes by. The more pressure (volume of air) the turbo is injecting into the engine, the more exhaust (volume) is being generated which is putting more pressure on the wastegate flap.

If the actuator spring doesn't have enough tension to hold the wastegate closed as the pressure on the flap increases, the flap will open and the tubo will stop increasing boost.

So once pressure on the wastegate flap exceeds the spring tension in the actuator, it doesn't matter if you don't have enough 'boost' being fed into the actuator, the diaphram is not moving from the air pressure pushing it toward the rear of the actuator anymore, it's being moved because it's being pulled by the wastegate flap pulling on the rod.

An easy way to check is to remove the compressor ('boost') feed to the actuator (just disconnect it from your boost controller - it doesn't need to be plugged up or anything to test this. You want the side that has the arrow pointing to it if you have one of those turbosmart ones. Otherwise it's the side that runs into the nipple on the actuator.
If you're really not sure, just pull the boost controller out of the line and leave them both open.

What you've effectively done is stop air being forced into the actuator, pushing the diaphram, and opening the wastegate.

*** THERE IS NOW NO CONTROL OVER YOUR BOOST LEVEL - BE CAREFUL ***

Now CAREFULLY get the car on boost and see if it goes over 10psi. If it does, then you have some sort of an air leak somewhere. If it doesn't build any more boost than 8-10psi then the actuator isn't strong enough to hold your wastegate closed and you'll never reach a higher boost with just the boost controller. You will need to replace your actuator (or modify it with more spring tension).

-Paul.

[codez]

Paul,

Thanks for explaining the function of the wastegate actuator and sharing how to check what the problem is, I will definitely do this test today or tomorrow and post up my results.

Thanks for explaining it in so much detail, I understand how the wastegate actuator works now

[codez]

I done the above test today and i hit 14 PSI before backing off.. seems I must have an air leak.

Im going to get new clamps and a new 90 degree bend hose from my 'cooler as I think this is the problem hose.

If this fails then i will try adjusting my BOV.

Thanks to the people who had constructive feedback and ideas/help

[Kedderz]

codez, follow this video http://www.youtube.com/watch?gl=AU&h...&v=atretf9u-Mc

will enable you to find your boost leak.

[Blair]

Thats a really good vid, thanks for the link.
+ Rep.

[codez]

Kedderz, thanks for the link mate it will be really helpful!

Also thanks for the previous help and tips