[NickD]

If you start to notice spark blowout during WOT it's time to take care of your plugs. I wasn't able to get to my spark plugs for three weeks and I noticed my daily commuting fuel economy dropped by about 10%. Even though I don't drive in WOT that much the plugs weren't igniting the fuel as well and I was leaving unburned fuel to go into my exhaust system.

Well the good news for the EPA, your catalytic converter is consuming those HC"s, but maybe not for you if you have to replace it.

Don't have to get nitpicky on the cause for a failed spark, blowby, excessive gap, excessive carbon on the center electrode insulator, poor connectivity, shorted turn in the ignition coil, poor connectivity to the ECU, water in the fuel, etc. All cause for a misfire, even dirty fuel injectors, or a dirty air filter.

Just tells you, its time to look at it. Check mine every 15K miles because I already know misfires will occur after this time. Always has, always will as long as we are pouring carbon in the fuel.

 

[NickD]

Engineer that said to gap the plugs at 65 mils was smoking crack when the HEI ignition system came out, misfires like crazy, also the very first year the catalytic converter came out that was very profitable for GM. They sure didn't last very long with misfires, lots of raw gas in there. Ha, starting to get paranoid, want to sell me more cats and made a very stiff law to buy one.

I stayed with the standard 35 mil gap, first vehicle with a cat was a 73 Fleetwood, put over 200k on that car, zero cat problems, much better fuel economy and performance.

Kid's new Kia Soul said 45 mils, they are also smoking crack with those super tiny coils on plugs, would get lost in my pants pocket. Has an MT, really had to hit the gas to prevent stalling the engine,not good on the clutch. Gaped those at 30 mils, what a difference, also picked up around 5 mpg.

Cruze with a bit more intelligence says 28 mils, believe me 25 mils works a lot better.