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Hey everyone, I've been dealing with this rough idle that leads to the car just dying after about 15-20 minutes of driving for a while now and I'm just about out of patience. It started with a rough idle that would start once the car had been driven for about 15-20 minutes, but that was it. It slowly evolved into a rougher idle that would, unless I gave it some gas, lead to the car dying. I've pissed away time and money looking for vacuum leaks with carb cleaner, swapping in used Coolant Temp Sensors, Swapping in a NEW Coolant Temp Sensor, pulling codes and finding nothing only to have a CEL pop up FINALLY telling me that it's an issue with an Idle Air Control Unit, swapping in 2 separate used IACV's, having no luck swapping these in and NOW it's gone from just the rough idle after warming up to a rough idle as soon as the car is started. Upon investigating this sudden change in symptoms, I found that my #1 injector isn't firing(checked by unplugging the connector and noting change in performance, along with listening for "clicking" with a stethoscope) The last time I had this issue(with injector #2), I swapped out the wiring harness, intake gaskets, entire fuel rail and cam sensor before it was fixed. I've tried another cam sensor, checked my coil-pack, installed a new spark plug in said cylinder, tried a new spark plug wire, and swapped in two separate used injectors and still no change. The only CEL that pops up using EITHER method of pulling codes is a #24 (IACV). At this point, my car has been sitting for about two weeks and I'm beginning to think that if I can't get it figured, it might be time to say goodbye, which sucks, because I love this car! Anyone have any other ideas as to what this could be? Sorry for rambling, but I have learned that the more info one can provide to the highly knowledgeable group of members here, the better the response. Thanks everyone!

So even after changing plugs & wires, and injector on that cylinder, it still doesn't change how the car runs/idles?

If so, I'd check to make sure you're getting spark on that cylinder. Since it's a waste spark ignition, chances are that you are getting spark.

Next I would check that you have 12v at one of the pins of the injectors with the ignition turned to the ON position. Next I'd check the resistance of the wiring from the other pin of the injector back to the ECU to make sure it's good. If that's good, I'd do a compression test on the engine, and if that's good, I'd replace the ECU.

When checking the resistance from the injector pin to the ecu, where on the ecu do I check it?

You need to unplug the ECU connector from the ECU and then probe the correct pin. That'd be the easiest IMO.

Why don't you find a local independent mechanic to take a look at it? Might have to pay they a little, but it's better than spending a bunch of money on stuff you don't need.

But +1 on everything 777 said. You may even be able to find someone with a spare ECU you could try.

make sure your pcv and all air lines are connected with no loss anywhere, i had a ghost vaccume leak once and experienced all these symptoms.

SubaruNation wrote:make sure your pcv and all air lines are connected with no loss anywhere, i had a ghost vaccume leak once and experienced all these symptoms.

Including the injector issues?

Yeah the car would just die

And what vacuum line did it turn out to be?

If the leak is big enough to do that it's a disconnected hose, would be obvious when you go to look

Check your MAF too, bad or dirty MAF would give same symptoms. If you try cleaning it be sure to use actual MAF cleaner...

Had similar situation on a different subaru (GLF) not legacy after a lot of suffering,
found the inlet pipe to fuel filter had a crack and would not let enuf in but return to the tank anytime the pump rested (engine off).
Not always easy to know which hose, pipe is leaking, if you know the area - try to swap all if you can.

^^^ The inlet pipe to the fuel filter? Now would that be the line running from the gas tank/fuel pump to the fuel filter? The line that runs on the top of the block and under the intake that carries fuel to the rail opposite the fuel filter (driver's side)? Or is it just one of the rubber fuel hoses attached to the fuel filter?