So, I just drove 500 mi to a vacation spot, and was close to "E". So I refilled, and within 2 miles of the gas station, my CEL came on. So, I pulled the code,a nd its a cyl. 4 misfire, 6 long pulses, 5 quick.

This tells me its either abad plug (copper NGK replaced 12k ago), a coil, or an injector.

I will re-set the CEL and see what happens, but what should I do to track this down?

BTW: The car is not running bad at all. The gas cap was on all the way (sometimes that'd throw an evap code)

 

first check the plug make sure it's still good, if it is then it's not your spark plug. next thing would be to switch out the coil on the no. 4 cylinder with another one drive it and see if the light comes on. if the light comes on then it's a bad coil.

 

Shut up.


1st thing you do is buy a spark plug tester. Pull out the coil and start the engine with the spark plug tester on the coil and see if you have spark. IF you do then you know its not a ECU, COIL or harness problem.

2nd, buy a can of propane (Small one if you can) As the car is running try to shoot some propane into the intake (Intake tube to the front valve cover) IF the engine gets smoother then you KNOW you have a Fuel related problem.

3rd. IF thats the case turn key-on and test Number 4 injector. If number 4 injector is at fault replace as needed. Take out the spark plug for cylinder number 4 and look at it. Infact pull out number 2, 4 and 6 look at all of them.

4th thing, Gas these days arent good anymore. Try using another gas station if this points to a gas problem. Sometime I get a small misfire due to some real ****ty dirty gas and I only use 93.

FYI

Resetting the ECU does nothing to improve on running conditions. Keep the cel on intill you solved the problem. Don't guess here, and don't throw parts into it intill the misfire is gone. All your doing is waisting your money and time. Diagnose it.

 

I started out with a cyl 4 misfire, mechanic told me it was due to oil leakage. Changed all o-rings and gaskets. Still got it and it got worse. Turned out the coils were going bad.

 

best way to do things is swap coil 4 with coil 5 and see if you get a fault for misfire #5. then you know if its your coil or not. But while your changing your coils around it doesn't hurt to pull the plug out and see.