At 09:19 AM 08/21/2002, you wrote:

>Some more questions, if I may?
>
>How does one successfully find a small vacuum leak and what is the best way
>to seal it?

Connect a digital tach to monitor small changes in rpm. Spray ether at the
many various possible points for vacuum leaks. A small consistent rise in
rpm with each squirt identifies the leak.

>Is the small exhaust leak on #3 a factor here?

Sometimes it can allow O2 to get sucked into the exhaust and the O2 sensor
will send a false lean signal to the ECU.

>Can testing the O2 sensor while it's plugged into the ECU damage the ECU?

Yes, if you use a cheap VOM. No, if you use a quality digital VOM with
protected circuitry. Also, NEVER disconnect or connect any terminals unless
the ignition key is off.

>I would think it's best to test it unplugged.

All adjustments, timing/idle/CO, MUST be done open loop, with the oxy
disconnected, as well as the several other adjustment/setup steps given in
the Bentley. After adjustments to spec in open loop with the exhaust gas
meter hooked up to the tap before the cat if you have a cat, or at the tail
pipe if you have no cat. Then reconnect the oxy (closed loop) and verify it
fluctuates properly from 0.3 to 0.7 volts. It should flux up and down every
second or faster. This confirms proper running. If it fluxes slowly or not
at all at this point the oxy must be replaced.