Re:Low Turbo Boost '86 5KCSQ

[Robert W Obrien <rwo@u.arizona.edu>]

On Thu, 16 Oct 1997, Alex Kowalski wrote:

> Did you do the output tests on the ECU that cause the WG frequency
> valve to click?  Did you pull the ECU codes?
> 
> It could be a stuck wastegate -- they're not that hard to take the cap off
> of and check.
> 
> Are you sure the turbocharger is spinning?
> 
> If the valve clicks and isn't leaking and the WG isn't stuck then it could be
> that your turbo is no longer spinning or you have a leak somewhere else -
> maybe the intercooler to throttle-body hose.  
> 
> Even without the backpressure from the WG frequency valve I thought
> the turbo should put out _some_ positive pressure with only the
> wastegate spring? Then again, maybe your dash gauge reads low but
> since you say you were seeing 1.4 bar this seems pretty unlikely.
> 
>  
I've been trying to sort this on my 5kt the last few days. I have a VDO
boost gauge plumbed in as per the Bentley. It reads 7 psi when under full
boost on 80 deg day. Within spec apparently. When the line from WG to freq
valve is removed and plugged, it does 8 psi- so the WG allows *more*
pressure this way? The codes/click test indicate a functional solenoid.
Incidentally, the dash gauge shows this as the difference between 1.2 and
1.3 bar...
Alex, didn't you get "weird scary boost fun" with a bad vac line to the
ECU and 0.9 bar- Corvette-munching overboost? 

I also thought disconnecting the WG solenoid would lower boost. I'll be
following this thread carefully...
Rob