Spark Plugs with Two-Step

[Ed Wright]

If you are tuning your air/fuel ratio with your wide band, when on the 2 step, it is actually very rich. The misfireing on the 2step puts a lot of oxygen in the exaust, which equates lean to an 02 sensor. All they measure is oxygen content, to calculate air/fuel ratios. You will see a bogus lean condition on your data logger. Rich there will dirty up the plugs in just a few runs. I have never had to change plugs during a race season. I put new plugs in each spring, just because. The plugs I pull out still look new. I've put a stock converter in mine to get a look at the actual WOT air/fuel ratio at as low as 3000 RPM. Sometimes it is hard to get the dyno to hold one that low for tuning at that low an RPM. Hope this helps. Just how I do it.