Thanks David,

I think you may have hit on something that's already
on my list to do today.  I have a very small
exhaust leak on the left side of the engine, right
at the head.  I'm going to reseal it today if it
stops raining.  The ECU-O2 communication may be
fouled by that leak.  I'll repair it and report
back.  Although I ought to mention that when the
02 sensor is disconnected, the vehicle seems to
run okay.  When connected, it loads up and bucks.

Thanks,

Warren Lail
88 Westy "Billy Bones"
87 GL "Long John"

>>Original Message -----
From: David Beierl <dbeierl@attglobal.net>
Date: Friday, March 26, 2004 6:06 pm
Subject: Re: slightly oily plugs

> Now measure what the sensor is putting out with sensor
> disconnected from
> the ECU -- should be somewhere between about 0-.2 volts (lean) and
> around
> .7 volts or so (rich).  If it's over a volt, you're getting
> leakage from
> the heater leads or some such.  If not, it should vary as you play
> with the
> throttle, and go to lean if you run it up fast and close the
> throttle --
> because the ECU  shuts off the fuel entirely until you get below
> 1500
> rpm.  This is much easier to see if you spin the wheels-- they'll
> keep
> things going long enough to read the meter and you won't have to
> run the
> engine very fast.  At the same time check the voltage on the ECU
> lead,
> should be steady right around .5 volts.
>
> If readings are reasonable, leave the meter hooked up and connect
> the
> sensor to the ECU.  What happens?  If things are working right the
> sensor
> will start flipping  back and forth btw lean and rich.  But
> exhaust leaks
> may draw in air and make it seem lean when it's not, in which case
> the ECU
> will richen the mixture until it overwhelms the leak.  At WOT
> (wide open
> throttle) you should definitely see rich, because the ECU stops
> listening
> to the sensor and richens the mix (I have seen an ECU that after
> running
> for a while would go lean at WOT instead of rich -- resetting by
> shutting
> off for an instant would cure it for a while.  No idea what causes
> that
> except I presume it's an ECU problem).
>
> If the reading goes to ground and stays there, chances are you've
> shorted
> the sensor lead to the shield braid surrounding the wire from the
> ECU.  That will make it run very rich.  (Ditto if the ECU shows 0
> with the
> sensor disconnected).
>
> david
>
>
> --
> David Beierl -- dbeierl@attglobal.net
>
>