99 corolla spark plug / oil - Toyota Nation Forum : Toyota Car and Truck Forums

ARIAS69 · 07-04-2009, 09:11 AM

Hey guys I have a 99 corolla, which had a miss fire , so i went and replaced the wires plugs n stuff. but when i changed the plugs i noticed that one of them was slightly coated with oil. i was wondering if anyone has had this and if so, was the problem ever uncovered? thanks

fishexpo101 · 07-07-2009, 02:15 PM

After you replace the plugs - run the car normally and then pull the plugs. See if oil has built up on the plug, if yes - could mean a problem with that cylinder.

If there was oil on the threads - that is less of an issue. Likely means the plug was not torque correctly or there was oil already in the sparkplug bore.

If you are able - try posting pics of the plugs. Could help someone else out with a similar issue or get more feedback to your post.

mechanic400 · 07-07-2009, 11:56 PM

Was the spark plug oiled from the "interior" side or the "exterior" side? The one I experienced was that the valve cover gasket I had was worn. Simple replacement of the gasket corrected the presence of oil on the plug from the "exterior" side (of the piston chamber).Good luck.

ARIAS69 · 07-09-2009, 05:37 PM

the oil builds up on the electrode side

fishexpo101 · 07-10-2009, 09:08 AM

Oil building up on the elecrode side is not a good sign - could be an oil control issue on that cylinder. That would cause a mis-fire, since the plug gets fouled by oil.

Do you notice any oil consumption on the car? If yes, how much oil does it go through. If you get a chance - do a compression test to see what the numbers look like. For the 1ZZ-FE values should run from 218PSI (max) to 145PSI (min) with no more than 15PSI difference between cylinders.