Miatapower List Archive

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Some months ago, we were discussing dirty tail-pipes, specifically Jackson
Racing ones.

I speculated that since the Oxy sensor was so much further from the point
of combustion (if you have a JR header), maybe it wasnt getting up to
temperature, and this was leading to over-rich running at nearly all times,
and thus black tail-pipes...

It turned out that because I got my header second-hand, and was using the
Mazda single wire oxygen sensor, my installation was non-typical, but Bill
C confirmed that my speculation was probably correct for my situation, just
not the rest of you...(who got a heated oxy-sensor with the original JR
header).


Well, I finally got around to installing a four wire sensor a couple of
weeks ago, so I thought I'd let you know my results.

1, The tail pipe still gets dirty, but slower than before. Its not all
black in a week.
2, Fuel efficiency has risen back to where it was when I first got the
car (approx 5%)
3, The car runs rougher under power (but not idle) than before for the
first minute or so (from cold) than before.
4, The car runs slightly smoother at all speeds after the first minute.


I conclude from #1,2 and 4, that our suspicions were correct.

I'm not sure what to make of #3, except to say I recall it might already
have started to happen a bit before the installation of the new sensor, and
may be the continued worsening of another un-related problem.

Ultimately though, I would say that it probably wasnt worth the $$ and
effort, except that I'm still considering a Link computer, and it would
have been necessary If I choose to continue down that path anyway.

Anyway, due to #2, it will pay itself off eventually anyway....

Has anybody got any clues as to whether #3 is related? and what else might
cause it?
My car used to drive away from cold, as smoothly as any other time I drove
it. Now, it hesitates a bit. (to say "coughs and splutters" would be
stating it way too strongly) it certainly feels like an old carburettor car
needing a bit of choke....

I'll try turning on the ignition, waiting a minute or three before
starting, then drive off. This should show up if its just the heat-up time
of the sensor.

Fletch.

P.S. Due to the annecdotal, non-scientific, way in which the above
results were arrived at and the short time since the change, it may all be
psychosematic hogwash ;-)