boost problem

[carl]

hi all
some of you may remember i used to have a big problem with fuel cut.i took your advise got rid of the saab hybrid turbo and got a standard leggy turbo and bingo no more fuel cut but i am only getting .5 bar of boost.any ideas what could cause this and whats the best way to check pipes for leaks as a visual check showed nothing.
thanks
carl

[vrg3]

The stock turbo's wastegate actuator is probably set to make about half a bar. You'll need a boost controller of some type to make more. If the factory boost control solenoid is still installed, you just need to plumb it in. This is what North American Legacy Turbos' vacuum lines look ike:

http://www.graphics.cornell.edu/~v/vacuum/

Your stock boost control is probably very similar. The relevant hoses are L, M, and K.

[ultrasonic]

.5 bar is almost 8 psi, I think. The wastegate spring should be somewhere around 5 psi (.34 bar). Allowing for a margin of error on your gauge, you may be seeing accurate stock boost level.

[carl]

ok thanks i have plumbed in the standard controller and am getting just shy of .5 bar depending on the gear.however although this is around 8psi i am feeling no difference the turbo is getting up to boost of 8psi quickly but the car accelerates no quicker.
whats happening.
just been out for a run and noticed it accelerates exactly the same on quarter throttle as on full throttle.
has anyone any ideas on what is causing this.
thanks

[vrg3]

Have you checked all the piping to make sure your boost isn't leaking out somewhere?

[carl]

hi
i have looked at the pipes but just looking i couldn't see anything that would leak is there a better way of checking than just looking at the pipes.

[vrg3]

You can sometimes tell a leak because there's a little oil around it... I guess if you had to you could try to seal off all the openings and apply compressed air to see if a leak develops.

I don't see how quarter throttle could be as fast as full throttle unless something was really really really wrong. You can barely make boost at quarter throttle. Is everything else on the motor in good shape? Injectors, oxygen sensor, fuel filter, spark plugs, ignition coils, stuff like that?

[carl]

everything else is fine the only thing i am worried about is the maf because when i got the car it was fitted with a induction kit and the maf was not secured.also when you start the car from cold it has trouble catching the revs.what i mean is if you rev it a little instead of the revs dropping smoothly they drop to about300 and then climb back up.
does this sound like a maf problem and could that cause my poor performance problems.

[vrg3]

Hmm, yeah, it could be a MAF problem. These sensors aren't especially delicate but if subjected to excessive vibration they can fail. I don't think yours has failed that way, though, or the car wouldn't run remotely right. You might have an oil-contaminated sensor though. Some people over-oil aftermarket filters, and the oil comes off and lands on the sensor.

Maybe pull the sensor off and give it a quick cleaning with some brake cleaner?

[wind chaser]

I have a similar problem with full boost at partial throttle and occasionally even more power as I back off the throttle. As I back off the throttle (if the tranny doesn't shift) it will pull harder as the boost guage drops to 5#. I have been suspecting vacuum leak (I have only 10" at idle) and/or TPS. I sprayed the vacuum lines with ether without any differences noticed. I also tested the TPS and something is up with it. When doing the test where pins are pushed into the wire connections, the ignition is on, and operating the throttle there is an odd sound. It almost sounds like a buzz that an electrical short makes. The reading goes immediately to 0 when this happens. ??? It is still drivable, but does this mean it is shot?

I am going to pull another TPS this Friday and see if it is better as has been suggested for TPS's. I would rather gamble on a used part first than cough up a wad if I don't have to.