QuestionHi, I have an intermittent running problem (hesitation, loss of power, won't
hold idle) that my mechanic has not been able to diagnose. I bought a scan
tool and got a PO170 code. Suggestions I've found are to clean the MAF and
the idle air control valve. I don't know what the IAC looks like or where it is
on my car. All I see attached to the throttle body, which I have cleaned is the
TPS. Does the 98 Forester have and idle control valve? If so, what does it
look like and where might I find it? thanks much
AnswerHi Karin,
P0170 fuel trim is a conditional code, meaning a specific condition is present causing the computer to command on the check engine light.
Your Forester has an Idle speed control(ISC)device but would typically not fail and especially in correlation with a p0170 code but anyways it is located below the throttle body on the passenger side.
I need to suggest that some one looks at the 02 sensor values, for a vacuum leak, for anything else that will affect fuel trim. The ISC typically will not, Im not suggesting you replace the 02 sensors but have them tested or at least use the data provided to diagnose the problem.
Not everyone in the trade will know how to do this properly or let alone what the values should look like on a Subaru, but it is better to diagnose the fuel trim issue rather than clean parts or worse replace the wrong ones.
Is there now one close to you that knows Subaru?
Justin
www.allwheeldriveauto.com
