2001 Subaru Legacy • 125,700 miles

Subaru Legacy GT 2.5 AT
Engine runs uneven, idle speed is not regular.
Changes already made are the following: sparks, cable spark, coil (bobbin), IAC valve, oxygen sensor (primary and secondary).

injectors mesurments are ok
All technician here said was the motor computer, so I change it, but the problem persist and steel runs uneven.

History: At the begining the engine runs with a loose of power, but when sparks and spark cable were change the power problem desapear. But idle seepd still irregular and engine also runs uneven.

Computer error code: Primary Oxygen sensor.
That is why primary and secondary Oxygen sensor and Computer engine were change, but this error code persist.
Also mesurements were made on primary sensor Oxygen on 6 cables, and 4 cables on secondary Oxygen sensor, all tested ok.

VIN number : 4S3BE64581 7201026

Please your kindly help cause I do not know what can I do with the run engine uneven and irregular idle.

Thanks in advance,

Rodrigo Bermejo
January 11, 2013.

Check fuel pressure first it should be 43.5psi. Then clean throtttle palte with choke cleaner on both sides as well as iac hole if you have one.

Jan 11, 2013.
Thanks for your fast reply, we do a full maintain to throttle pallet and IAC hole and valves.
Also we measure pressure and it was on 43 psi.

What else can be? On high RPM (over 2000RPM) the car and engine do it very well and normal, is on low RPM that problems occur.

Best regards,

Rodrigo Bermejo

Jan 14, 2013.
Chekc intake vacuum if 15" or below suspect clogged converter. Then scan for code again, also spray around engine with choke cleaner looking for a vacuum leak

Jan 14, 2013.