I’ve got some questions about this check engine light crap on my Subie. Sometimes it flashes and stays on when the gas tank is full then goes out when the tank is below half a tank. After reading in my manual about the fuel cap issue I got the light go off. The light came back with the same pattern as before and I Start having cranking issues and a smell of gas when trying to start. I changed a fuel censor and the fuel filter though the problem was solved. Now the damn light is back on with the same pattern as before but without the fuel smell or starting issues. Codes coming off the computer are number 4 misfiring. I drive the car and have not notice it misfiring. Before I spend $150.00 on plugs and wires will someone give me some cheaper options?

 

Thanks

 

Patton2tank

Replace and pray that problem would go away is not a good strategy. Will lead to continued symptoms.

 

If cylinder 4 misfire try these simple things:

 

1. Swap 2 and 4 spark plugs and see if problem moves to 2.

2. Make sure plug wires are in securely. Swap 2 and 4 plug wires and see if problem moves to 2

3. Ensure injectors are working by using a screw driver and listening for clicking sound. Add fuel injector cleaner, just in case injectors are clogged

4. Use an digital meter to ensure right resistances on plug wires/injectors/ignition coil

5. If valves might be sticking, add a solvent for that.

Thanks I will try what suggested

 

 

 

Replace and pray that problem would go away is not a good strategy. Will lead to continued symptoms.

 

If cylinder 4 misfire try these simple things:

 

1. Swap 2 and 4 spark plugs and see if problem moves to 2.

2. Make sure plug wires are in securely. Swap 2 and 4 plug wires and see if problem moves to 2

3. Ensure injectors are working by using a screw driver and listening for clicking sound. Add fuel injector cleaner, just in case injectors are clogged

4. Use an digital meter to ensure right resistances on plug wires/injectors/ignition coil

5. If valves might be sticking, add a solvent for that.

If the problem is only when tank is full, it might have something to do with evaportative system (for vapors). If you fill the tank only till 1/2 mark everytime, does the problem not happen? If you haven't tried it, try it as well...

Good wires and plugs shouldn't cost more than about $60.

 

Because of the misfire code, follow what people have suggested, but if you get a gas cap code, look at and tighten every hose and gasket in the fuel/evap. system. Even the ones you can't easily reach. Buy a new gas cap too. What's the fuel sensor? If you replaced the sending unit, it should have had a new gasket too.