Spark Plug Reading was: WPSLPGExhaust Gas Oxygen (EGO) sensor Information

[Jörgen Karlsson]

> etc.).  I've heard that in order to be able to best anaylze the
> plugs it is
> best to shut down the engine immediately after a test situation, say for
> instance running at typical highway cruise ... and that driving
> the car home
> after the test will render the readings on the plug inaccurate ... what
> think ye?  Are you all pulling over to the side of the road with a hot
> engine and pulling plugs?

My experience from reading plugs are mostly from the time I drove motocross,
I on the two stroke engines it is very important to kill the engine
instantly at the load point you want to check. A few seconds of idle will
destroy the reading completely. On the 4 stroke bike I had it was also
beneficial to do this, even if the reading could be taken after driving back
to the pits on this bike.

Just remember that this technique is not very smart on a turbo car if you
haven't got a turbo saver that continues to flow oil through the turbo after
the engine has stopped. Unless you can pull all the plugs and replace them
with new ones and start the engine in 30seconds;)

Now I only use plug readings to check if it is the right plug and to check
for distribution problems. Of course I used plug readings to find out which
cylinder it is that usually detonates first.

Jörgen Karlsson
Gothenburg, Sweden

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