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- - Rough Idle (https://www.subaru-svx.net/forum/showthread.php?t=54357)

All,

Been fighting a rough idle for about a year now. I was getting a CEL and I jumped the ECU and figured out that the light was the O2 sensor on driver side so I immediately replaced it. I then started it up got another CEL, jumped ECU again and found that it was a bad knock sensor. I replaced both of those and started up the car. Still runs rough, now with no CEL.

I tried seafoaming the car to no avail. I have been using gas treatment and stabilizer in the tank. I checked to see if maybe faulty spark plug wiring or a grounded plug, nothing of the sort.

The engine runs like it has a vacuum hose undone. I've checked everything but nothing seems to be undone. The car shakes and there is a "putt putt putt" coming from the exhaust. Last ditch effort is that I have not changed #6 plug during the last plug change and perhaps the plug is fouled up? I doubt it as the car has just over 60k on the clock and the others were clean when I pulled them a year ago (l've put less than 1000 miles on the car since)

Anyone have ANY ideas? I am running out of alternatives, help!

Thanks,

Yoshi

Quote:

Originally Posted by ykobayashi (Post 644836)

All,

Been fighting a rough idle for about a year now. I was getting a CEL and I jumped the ECU and figured out that the light was the O2 sensor on driver side so I immediately replaced it. I then started it up got another CEL, jumped ECU again and found that it was a bad knock sensor. I replaced both of those and started up the car. Still runs rough, now with no CEL.

I tried seafoaming the car to no avail. I have been using gas treatment and stabilizer in the tank. I checked to see if maybe faulty spark plug wiring or a grounded plug, nothing of the sort.

The engine runs like it has a vacuum hose undone. I've checked everything but nothing seems to be undone. The car shakes and there is a "putt putt putt" coming from the exhaust. Last ditch effort is that I have not changed #6 plug during the last plug change and perhaps the plug is fouled up? I doubt it as the car has just over 60k on the clock and the others were clean when I pulled them a year ago (l've put less than 1000 miles on the car since)

Anyone have ANY ideas? I am running out of alternatives, help!

Thanks,

Yoshi

The vacuum leak is likely. Get a piece of hose as a stethoscope, one end to your ear, poke the other end around under the manifold, to hear any hissing sounds, where the leak may be.

Harvey.

FYI: A common vacuum leak occurs under the manifold between the alternator and PS pump it's an S-shaped hose. Another occurs at the opening to the TB from improperly installing the intake hose. Did you try resetting the ECU after changing the sensors you mentioned. Also, do you run a K&N air filter?

I saw you do use a K&N, try cleaning your MAF Sensor