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Subject:Diagnosing Issue using O2 Meter during Open-Loop Operation
From:Rocket J Squirrel
Date:Wed, 9 Sep 2009 17:42:43 -0700

Mellow Yellow went through a couple days of weirdness last week. When
first started, the engine had no power for several seconds. Stepping on
the gas didn't do a whole lot. Then it would catch and run fine, sort of.
There was a bit of a miss, and I think less power than usual. Of course
it's fixed itself now. But anyway.

I have a Ken Lewis O2 meter and during the initial open-loop operation, it
read normally, in the middle of the scale, even when running poorly.

If the problem had been ignition-related (bad plug wire, fouled plug) I'd
expect that the mixture would read rich when the ECU was running
open-loop, yes?

If the problem had been fuel-related (plugged injector) then the O2 meter
would say that the mixture was lean when the ECU was running open loop, yes?

So I'm puzzled about what could cause engine gutlessness and a slight miss
(which seems to have fixed itself) w/o something reading wrong on the meter.

--
Mike "Rocket J Squirrel" Elliott
84 Westfalia: Mellow Yellow ("The Electrical Banana")
74 Utility Trailer. Ladybug Trailer, Inc., San Juan Capistrano
Bend, OR
KG6RCR