Thread: "Check Engine" Light On - EJ25

hey guys, i have a subaru liberty 1997 RX (EJ25), the check engine light comes on. The car misfires from time to time but only when it then engine is at normal operating temperature, this sets the check engine light but the problem is intermittent. I have changed the leads and plugs as they were due anyways but its still misfiring. Any Suggestions???

Hi. Do you know if the Liberty has an ODBII port? Reading out the codes might make sure that it is indeed misfire and not something else. In the US market anyway the misfire codes would come back as P0301, P0302, P0303, and/or P0304 for cyls 1-4. Sometimes if the MAF or other things are going flaky it can make the engine sputter or otherwise seem like it is misfiring, and the code might be for that.

If it is really misfiring, sometimes soobs can be picky about the brands of spark plugs and spark plug wires. That engine probably has solid lifters (rather than hydraulic). If it has a lot of miles on it and the valve clearance was never checked/adjusted there is a slight possibility of one or more valves not quite closing all the way and causing misfire?

Another thing to check might be the knock sensor. On that era they liked to develop a nice crack and then intermittently throw codes for the knock sensor circuit. I've had that happen and it can feel like a misfire because the ECU suddenly is retarding the timing to edge of the map as a failsafe to protect the engine.

If you need more info or have other questions just let us know! Oh and

thanks mate for your input. i the other night i got the engine to normal operating temperature and revved it from the engine. I noticed a short circuit near my coil pack. rather than the travelling down the lead ot the spark plug, it was earthing straight out of the coil pack on to the throttle body. i changed the coil pack as a mate of mine had a brand new spare one. and still found it misfiring but thanks i'll check the knock sensor and see how it goes.

Great it sounds like progress. Yes I forgot about the coil pack tower cracking/carbon tracing. There was a TSB from Subaru out about that potential issue on that era soob.

Do you know which cylinder(s) are misfiring? If so you could try swapping around the spark plug wires and if the misfire follows a certain plug wire it might be faulty.

How many miles does she have?

Oh if you're looking into the knock sensor, there's some info and pictures in the Subaru knock sensor article.

Originally Posted by liberty97

not exactly sure which cylinders are misfiring, she has 167000 kms on her (dont know what that converts into miles). yeah i think i'll check the knock sensor aswell just for fun because it may be worth it in the end. i was thinking about swapping the lead around but the leads and plugs are brand new.

Hi Liberty97. (Your post came in during our software upgrade so I had to copy it over manually to the new version )

What brand leads and plugs are in use? That era soob can be pretty picky, seeming to prefer NGK spark plugs and genuine or Magnecor leads. There was a TSB out for US soobs of that era about something with the plug wires that could cause misfire....if I have a chance I can see if I can find it.

167km is about 104,000 miles. If she hasn't had the timing belt replaced yet she's about due for that as well, and valve clearance check and adjust.