Looking for help diagnosing an issue on a friend's Forester:
2001MY Forester 2.5 SOHC Auto
(Note: these are speed density, no pesky MAF to point the finger at)
Here's the rundown:
Idles rough, distinct misfire visible (engine shakes/car vibrates) and audible at idle. Clears up when opening the throttle / driving.
Tube seals and rocker cover gaskets just replaced, new ignition cables, coil pack, spark plugs (correctly gapped), new PCV valve.
Problem persisted in the same manner after the replacement of the above.
Had one code for an O2 sensor, replaced the sensor and the code never returned, no difference present in idle/drivability.
Drove the car for several miles, several key cycles, sat idling for a good while and still hasn't thrown a code.
Here's the strange part:
Out of ideas, I decided to pull the (newly installed) plugs to see if that would lend me any clues.
On the passenger side bank (1&3) the plugs looked black (not fouled, rich)
I only had enough time/light/patience to remove the leading plug (cyl. #2) on the driver's side. This plug looked like this cyl was running very lean, it was completely while (no tan appearance at all.)
My Thoughts:
Vaccum leak?
Timing off?
Burnt exhaust valve?
Valves out of adjustment? (They are completely quiet)
^ All seem theoretically possible to me, however the different appearance of the plugs has thrown me for a loop.
Faulty/clogged injector (cyl 2)?
Once again: no check engine lights. Plugs indicate Bank 1 running rich, Bank 2 Lean
Thanks in advance.
2001MY Forester 2.5 SOHC Auto
(Note: these are speed density, no pesky MAF to point the finger at)
Here's the rundown:
Idles rough, distinct misfire visible (engine shakes/car vibrates) and audible at idle. Clears up when opening the throttle / driving.
Tube seals and rocker cover gaskets just replaced, new ignition cables, coil pack, spark plugs (correctly gapped), new PCV valve.
Problem persisted in the same manner after the replacement of the above.
Had one code for an O2 sensor, replaced the sensor and the code never returned, no difference present in idle/drivability.
Drove the car for several miles, several key cycles, sat idling for a good while and still hasn't thrown a code.
Here's the strange part:
Out of ideas, I decided to pull the (newly installed) plugs to see if that would lend me any clues.
On the passenger side bank (1&3) the plugs looked black (not fouled, rich)
I only had enough time/light/patience to remove the leading plug (cyl. #2) on the driver's side. This plug looked like this cyl was running very lean, it was completely while (no tan appearance at all.)
My Thoughts:
Vaccum leak?
Timing off?
Burnt exhaust valve?
Valves out of adjustment? (They are completely quiet)
^ All seem theoretically possible to me, however the different appearance of the plugs has thrown me for a loop.
Faulty/clogged injector (cyl 2)?
Once again: no check engine lights. Plugs indicate Bank 1 running rich, Bank 2 Lean
Thanks in advance.