1.4 bar low boost and recent owner impressions

Dan Cordon cord4530 at uidaho.edu
Thu Jan 29 00:45:08 EST 2004

I agree too, that it's less likely that the display is off, but it is a
possibility. Though, since Ken has mentioned that it doesn't seem as fast
from 50-80, I'm much more inclined to believe that it *is* low boost, and
not just false readings.

I know on my 87 5kcstq that my digital display is off by 0.4 bar. But it
reads low, not high. It idles at ~0.2 bar, and decelerates at 0.0 bar.
And at 1.4 bar it is actually at 11 psi (1.8 bar). Initially I thought
this was because someone had done a diode hack on the ECU. However, I
recently got a different ECU and the display is exactly the same. Either
way.....that's probably an issue for a different list :o)

How about plugging the bypass hose (make sure to block both sides!) for a
few short tests to see if there's any changes. While I wouldn't recommend
it long term, a few test drives shouldn't harm anything. That should
isolate any problem with the BPV. Also, if you continue to hear the
*woosh* noise w/o the BPV installed, that tells you something too.

Looking through my 20V training book, the throttle pot., altitude sensor,
MFTS, and knock sensors could be likely problems. And of course, any
leaks could behave similarly, but you'd be running really rich. It looks
like you've already got a good handle on where to check. Keep us updated!

Phil Rose wrote:

> <snip>
> Good advice, if he's planning to install another gauge anyway, now
> would be a good time to do it--to be sure.
> That said, I've never heard of the dash display gauge being _that_
> inaccurate. I wouldn't necessarily get too worked up about seeing 1.6
> bar without verifying with a good gauge-- but 1.4? That IMHO very
> likely indicates a real boost problem.
> For sure, a '91 200q isn't that much fun at 1.4 bar, but the
> perception of 1.4 bar performance will depend on whether or not
> you've accustomed to full boost.
> What's that old saying? Oh yeh:
>   "I been _down_ so long that it seems like _up_ to me."
> Phil
> --
> Phil Rose
> Rochester, NY
> mailto:pjrose at frontiernet.net

Dan Cordon
Mechanical Engineer - Engine Research Facility
University of Idaho

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