User avatar
By yogi b
posted previously:

The most accurate tuning diagnostic for timing and afr are not wide bands but spark plugs

Reading plugs is very old school, but a very accurate way to judge what is actually happening in your engine

The procedure is very simple and is called “cutting clean”

You make an all out run and shut down the motor, coast to a stop[clutch in] and pull the plugs.
They will tell you exactly what is going on in your motor long before any gauge

It takes some practice, here are helpful articles

Here is a chart describing what you may find
Simply match up your plugs and you will know ... 2453241270
general theory from ngk ... 2453241270

I ran all my past 6 seasons on this technique alone
It only failed when I didn’t do it
Until now, there has been no other than the stock gauges in my car
User avatar
By skyy
aem fi/c data log is awsome, just start logging, do two or three pulls, sit at ur house make graphs and see what happens to your a/f in w.e rpm u want :D
User avatar
By yogi b
data logging is great
i'm not knocking it
but when race day comes pulling the plugs is the final word for many race teams
it is a snap shot of the real combustion temps taking place

of course you should use both
after all they should agree
and are a good check on your wide bands accuracy [the o2 sensors fade with time]

i'm just saying
here is a way to tell for sure that no preignition or detonation is taking place
User avatar
By KingDNH
Yeah, data-logging is really simple and quick, but you never know if the O2 sensor is giving you accurate readings.

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