Help with CIS

Huw Powell audi at
Tue Feb 11 23:54:19 EST 2003

> Well, I went over my engine and replaced the braided vacumn lines with new
> ones.  So then I decided that I was going to try to tune my CIS-E so I
> hooked up the multimeter and all.  No signal whatsoever.  I even went back
> to my old o2 sensor, still no signal.

You are measuring the output voltage of the OXS relative to a good
ground while itis hooked up, right?

 > So I took my car to my "oh crap"
> mechanic and he says my electronics are fubared.

The OXS doesn't really depend on the ECU, although of course the ECU
must be working for the OXS output when warm to be a nice varying signal.

> If you remove the "spare"
> fuse the engine revs up, not down.  I would think that when I remove the
> spare fuse the engine would die or start to sputter.  Does anyone have any
> ideas?

what you see is correct, and also, btw, proves that the ECU is at least
partly working, since it runs the ISV.  Your ISV is probably one of the
ones (you don't say what year or model...) that is partly open at rest.
  At idle, the ECU action results in it being more closed than that, so
when you kill off the ECU by pulling its fuse, the ISV opens up a bit
and the engine speeds up.

> My car is running so rich it is stinkin bad, and my gas mileage is
> horrendous.

Is the block well grounded?  Are the intake manifold grounds in place
and good?  have you tried measuring the CPA current?

Huw Powell

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