2002 Toyota Corolla Misfire codes PO300+PO302

DAVE1310

MEMBER
2002 TOYOTA COROLLA
4 CYL

When the weather finally warms up in Wisconsin I will have to trouble shoot this code again this year, it runs very good and smooth after warming up for about 1-2 minutes-I do suspect a possible burnt valve, bad piston rings, or maybe a completely dead cylinder (#2)- if it is one these labor intensive problems to fix-is it terrible to let it go-the car runs well and smooth-but does burn some oil it is basically used by me as a second car and for short town trips/errands is it OK to let it go? Any input will be appreciated- I forgot I plan to do another compression test the mechanic that did it for me before lost the #'s

1 Reply

CARADIODOC

MECHANIC
33,871 POSTS

So sorry to hear you're in Wisconsin. I am too, and I really hate cold and snow!

How many miles are on the engine? A cylinder leakage test will tell you if an intake valve, exhaust valve, piston rings, or cylinder head gasket are leaking. Auto parts stores that rent or borrow tools should have that tester. You can switch the number two injector with one of the other ones to see if the misfire moves to the other cylinder.

You didn't list the engine size either. If you have one of those that used coil-on-plug, swap two ignition coils too, but with a different cylinder than what you used for the injector. If the misfire switches to that cylinder, suspect the coil is breaking down internally.