Intermittant boost problem

[Guest Chri5]

Ok firstly its an Aristo so dont shoot me, Im trying to get a decent solution

 

In short, Ive done all the BPU mods, and had a double decat made yesterday in 2.5", with a 1.75" RR. The rest of the system is 3" mid into 2x 2.5" rear sections with a backbox each side.

 

Took it out and still only hit 10psi, although spooled up a bit earlier and had a bit more torque low down.

Maybe the ring is too small, so filed it out to just under 2", exactly the same again, 10psi and not a pound more.

 

So today I removed it completely to try that, STILL the same, 10psi. This is with the 2nd Turbo coming in also Ill add;)

 

By now Im getting a bit miffed so did a bit of reading up on the sequential system, and all the VSV's etc etc

I noticed the only thing that looked "wrong" was the IACV VSV, as it had what looked like a vac line attatchment with nothing on it, see pic....(this isnt actually mine)

http://exactjdm.com/help/engine%20bay/DSC_0241.jpg

 

Hmmm, I thought ill try blocking it. Went down the road, and boost would easily hit 20psi+ but I let off at 16. It did this a couple of times, then wouldnt go over 10psi again

Ive sinced removed the blockage and left it how it was, but the same result.

So this has pretty much narrowed it down to the IACV.Also the IACV VSV is electrically connected to the EGBV VSV too is it not?Is there any way to test as to which one may be the problem?

I moved the actuator arm for it manually to make sure it moved, its quite stiffly sprung, not sure if thats normal? I know that this not fully opening will not allow enough intake airflow to make the boost levels needed.

Any other ideas or possibilities?

Cheers guys

Edited June 4, 2009 by Chri5 (see edit history)

[Guest Chri5]

Done a bit more testing....

Firstly, I hooked it up in TTC mode, that boosted fine to about 16psi after bypassing the IACV

 

I T'd my other boost gauge up to both sides of the IACV VSV, to monitor if its seeing pressure.

On the pressure tank side, sure enough it boosts up as it should, it was around 11psi or so when I let off.

THEN the VSV SHOULD switch and allow this pressure through to the small actuator on the inlet,thus opening the path for turbo 2's boosted air.

 

I then T'd the gauge into the actuator side, to see whether the VSV was switching and directing the air to the actuator. It didnt, none whatsoever.

 

So I think its safe to say that for some reason the VSV isnt switching as it should, and it does physically work as I tested it earlier with 12v.

I even tried a different ECU to rule that out, the same thing happened.

 

Any ideas folks? PLEASE, I'm not seeing much response