99 Toyota 4 runner 3.4 Liter

by Mark
(Escondido, San diego, Ca.)

The runner is throwing po302 code. I've changed the spark plugs. Today I switched the #1 coil pack with #3 coil pack to see if the misfire followed it, it did not?
I sprayed water on spark plugs tonight to look for arcing and saw none?
please help

99 4runner 4x4 3.4 sr5


Answer

Hi, Mark! There are a couple things that you need to do to narrow this down. The first is a compression test on the #2 cylinder as well as one or two of the other cylinders. See if the #2 cylinder is lower on compression than the other cylinders. It sounds like you have done some good tests to check parts of the ignition system. You should switch one of the spark plug wires with the #2 wire. This will tell you if the wire is a problem. If the spark plug wire is bad it can be hard to tell so definitely try this test. If you still don't find the problem then you need to switch one of the fuel injectors with the #2.

Whatever the problem is with this type of code (or similar codes like p0303, p0301, p0304, p0305, p0306, etc.), it is something that is isolated to that one cylinder, keep this in mind as you are working on diagnosing it. Remember that a cylinder needs fuel, spark at the right time and compression in order to fire.

Good luck with your problem, and remember the simple stuff. Don't give up, unless you have exhausted all or your ideas. Thanks for contacting me.

-Steve