2002 Mitsubishi Eclipse random misfire code P0300 only

FIVEFORTUNE

MEMBER
2002 MITSUBISHI ECLIPSE
4 CYL
FWD
AUTOMATIC
129,000 MILES

The code p0300 - Random Misfire started occurring about 2 months or 7,000 miles after a engine head rebuild due to a stripped spark plug thread in cylinder 2. The car ran just fine after the top half rebuild until some 7,000 mile were racked up. As I could not diagnose the problem, I took it to the dealer who then advised that I replace the spark plug wires, boots, plugs and PCV valve. This was done but the problem still occurs. Both coils were tested and so was the cylinder compression which were normal. The dealer then proceeded to recalibrate the ECU and after which it ran fine for 2 days. As recommended by the dealer, I cleaned the throttle body, making sure to capture any excess cleaning fluid with a clean towel under the butterfly opening. After drying and re-assembly of the air inlet housing (the battery was left connected during this procedure) the car ran fine for another 40 or so miles (a full day). Then, the Random Misfire started again. The car is still not fixed and I have spent a lot of money going nowhere. Can you offer me any suggestiosn as to what could be wrong. Thanks.

1 Reply

ELGATOS63

MEMBER
2 POSTS

I have had the same code come up on my '01 galant and I have disconnected the battery, let it sit for 10 minutes and re-connected the battery then let it idle till it gets up to running tem. By that time it has "re learned" the timing. I have only had this problem once, and it was after I changed the timing belts. If it starts running poorly after trying this check the timing marks, you will probably have to remove the top part of the timing cover to see the cam marks but use the timing marks on the crank to verify they are correct. If they are correct you may have a bad cam or crankshaft sensor, each sensor is about fifty bucks. The cam sensor is easy to change but the crank sensor is under the cover and you have to remove it just to see the sensor. I hope this helps.