2002 Toyota Corolla PO300/and PO302 codes CEL

DAVE1310

MEMBER
2002 TOYOTA COROLLA

You guys have helped me out many times before, I am dumb founded about a CEL with the above mentioned codes pulled. Ignition system is all new coils, plugs, MAF, ect, the car idles well and smooth for over 1 hour without the CEL on. Then when I get in and drive it for about 2 miles the CEL comes on, visually I can't see any vacuum leaks, cracked hoses seem to be OK and many have already been replaced since they are a cheap fix. Any ideas of what issue may be possibly?

5 Replies

JACOBANDNICKOLAS

MECHANIC
109,740 POSTS

Those codes indicate a cylinder misfire. If there are no vacuum leaks, have you checked fuel pump pressure? Have you checked engine compression? How many miles are on the vehicle?

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Wednesday, February 25th, 2015 AT 3:59 PM

DAVE1310

MEMBER
63 POSTS

Thanks for response-mechanic says fuel pressure very good, compression is moderate but OK, I have 196,000 miles on car-could it possibly be a hidden vacuum leak or a blown gasket-I have been at this diagnosis for about 1 year-the car runs great-do you have any ideas? Does it sound like a vacuum leak?

Like I said in my initial post it seems the car can idle forever without the CEL coming on-but after I drive it for a short distance 2-3 miles, the light comes on

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Wednesday, February 25th, 2015 AT 4:24 PM

JACOBANDNICKOLAS

MECHANIC
109,740 POSTS

The PO300 indicates a random misfire which could be the result of a vacuum leak or even an ignition problem relating to the crank sensor, a weak coil, a bad ground.

Is there any way you could find out what the compression readings were for each cylinder?

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Wednesday, February 25th, 2015 AT 7:20 PM

DAVE1310

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63 POSTS

Thanks-I will see if he has those compression numbers yet-but in the meantime I will check out the CPS with an Ohm meter, I never even thought of that-Thanks

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Wednesday, February 25th, 2015 AT 7:33 PM

JACOBANDNICKOLAS