boraxman

So I have come to realize when my Taco starts missfiring its time to replace a plug. I have tracked down this occurance 4 times in 2 years, 2x in #3 and 2x in #6 cylinders.

Whats happening is my plugs are cracking on the porcelian where the electrode comes out. Very hard to see but there and the problem none the less. I only use NGK or Denso dual electrodes.

My engine generally runs perfect and has 162K, its a '96 and has had the head gasket recall done and always serviced. All coil packs, wires etc. replaced.

So anyone else have this problem or know of a cure? Maybe im running lean?

icerunner

I give you props, you're are a smart dude (smarter than most) to know that misfiring is mostly with the Spark plugs.
A lot of guy don't realize that the plugs are 30,ooo Mile plugs max..... Yet, it sounds like you have a different issue all together.

Thinking out loud, if too lean a fuel mixture:
1)dirty injectors?
2)dirty fuel filter?
3) Dirty M.A.F Sensor?
...maybe...?

My question: What brand of gas are you running?

boraxman

Ha, didnt think I would get a reply. Hopefully it may help one person.

I use regular gas from various stations.

MAF has been kept clean but aging none the less.

Injectors never serviced.

Fuel filter about 50k ago.

icerunner

I can honestly say I have no Idea but i suspect it may be the injectors in the suspect cylinders spraying too lean... or semi clogged? You may want to try a "top tier" fuel such as BP or shell and go with the BP ULtimate or Shell Ultimate as i think they add much more cleaners than the standard grades and that may help with the injectors..
Please let us know what you find out

icerunner

Hey,
any news on the issue?

tntempest

You left out the pre-cat oxygen sensors, that play a vital role at determining rich and lean. To clean the injectors you could use seafoam, in tank, and to clean valves put some in the intake.

hross14

------While the engine is running

Read the other plugs to see whether they are running rich. If they are sooty and have lots of carbon on them--Then the clogged injector theory could be correct. i.e. O2 sensor richens the mix to account for the lean condition in the clogged cylinders. Hence the unclogged injectors would dump more fuel until the mix is correct--The down fall of only having one O2 sensor.