Legacy GT 2009-service engine light from mis-fire

[Dorothy]

I have a Turbo Legacy 2009 with about 140,000 miles. The engine service light has come on. Per the dealer's service there is a mis-fire in one cylinder and needs a valve job for $4,000, but that might not cure the problem (they indicated they would be happy to take it in trade). We are now working with an independent shop about 500 miles away. Cylinder pressure is good and the car runs well - good acceleration and the engine only "misses" rarely - 500 to 1000 miles which "trips" the service engine light. When the service light is tripped the cruise control and the "S" settings flash and do not function. I cannot switch back to the "I" or "S#" modes.

 

Both coils have been replaced and injector cleaner has been run through the engine. I have been told the sensor on the 4th cylinder is the one indicating the fault/mis-fire.

 

The shop feels that it appears to be a fuel problem - but the injector cleaner has not helped. What are the possible sources of the problem and what can we do - at least what can we try?

Thanks.

[SBT]

Moved to 4th gen Legacy Sub-forum

[BarManBean]

You should be starting with the coil packs / plugs / injectors. If you have already replaced the coil pack with new OEM replacements you should be able to eliminate that as a potential issue. Did you check the plugs? Wouldn't be the worst idea to replace 'em all with new OEM replacements that are properly gapped depending on previous service interval.

 

Next would be injectors, and just running an injector cleaner through the engine isn't going to cut it. You will want to swap the injector over to another cylinder to see if the misfire follows the injector. If that's the case you'll probably want to have the injectors cleaned professionally.

[SPooky_leggy]

as stated before, injector cleaner is not enough, swap out injectors form another cylinder and also inspect them while there out for wear and damage, as that could cause random misfire in a particular cylinder! keep us updated and GL!

[Max Capacity]

You can also move the coil pack from another cylinder too and see if the CEL follows. That's what any decent repair shop would do. Not tell you $4000 or we'll give you a good trade in...Don't go back there again.

 

There is no "sensor" on any of the cylinders that I know of. The miss fire is sensed by the ECU. But I could be wrong, I'm not an expert on engine sensors.

[MrTris]

You can also move the coil pack from another cylinder too and see if the CEL follows. That's what any decent repair shop would do. Not tell you $4000 or we'll give you a good trade in...Don't go back there again.

 

There is no "sensor" on any of the cylinders that I know of. The miss fire is sensed by the ECU. But I could be wrong, I'm not an expert on engine sensors.

 

Knock sensor is directly over 4.

[Max Capacity]

Knock sensor is directly over 4.

 

 

Yes, I understand that one knock sensor. That is different then a miss-fire, isn't it ?

[JmP6889928]

Tell your service people to remove the coil packs-all 4 of them (might as well put plugs in it while these are out and have them examine the plugs for any sign of aluminum dust on the electrodes) and reach inside the electrical connection point with needle nose pliers and lightly twist the connectors a bit and then apply a very light amount of dielectric grease to the pins (too much is NOT good) and while they have them out, have them swap the #4 and #1 coil pack just for good measure, then re-install.

 

One of the issues with these cars is that the plugs that are the power feed to the coils become a bit loose after several years and by twisting these pins, it allows them to make better contact and in many cases, eliminates the misfiring situation.

 

If that doesn't help, then it's time to remove and swap fuel injectors as everyone says because if it is, in fact, a bad injector, the misfire will follow and then you'll have your answer.

 

Good luck.