So I just went and washed my runner. I cleaned out the engine bay as I have for years, no high pressure and try to stay away from intake and such. Now it's misfiring but it won't throw a check engine light. I pulled all my injector wires and pretty much all other plugs and everything was bone dry. My coils are within ohm spec. Pretty hard to track this down without a code to tell me where it's coming from. Also, when it first starts, it runs fine for several minutes before starting to misfire again. Any ideas?

 

You likely have pending codes if you hook up a scanner. It takes repeated misses within a set of parameters to go from a pending error to a fault.

 

If it started after washing, give it a good day in the hot sun and see if it goes away.

 

In the old days before computer modules and coils-on-plug, we would just pull the plug wires one by one. The wire that made no difference was the one to the misfiring cylinder. The waste spark system on 4Runners makes that more complicated but you could try unclipping each of the three igniter wires at their respective coils and see if one makes less of a difference.

 

I plugged it into a reader and sure enough, multiple random misfire and misfire on cyl 2. Both pending. I'm gonna try to start it again tomorrow. It sat out all day in the sun. If it's still doing it I'll pull my supercharger and check cyl 2 injector and go from there. Thanks guys!

 

When was the last time you cleaned your MAF?

 

It ended up being a bad plug. I started with that since it was the easiest to change. New plug and no misfire. Not sure what would cause it to go bad. They're denso plugs and only 30k on them.

 

Beware it may come back when the motor is hot. There is a rash of CEL incidents with isolated misses, myself included.

It could be plugs, wires, injectors, MAF, or O2s.

 

I checked the resistance in my wires and there were within spec. Pulled plugs and made sure injectors were firing. I just replaced my a/f ratio sensor last week and clean my maf a month or so ago. Fingers crossed its just an isolated incident. Drove her around for about 30 minutes and it hasn't come back.

 

30k is the recommended mileage for these plugs.