My '97 Legacy (Brighton) wagon suddenly started idling quite fast. It also spins down slowly between shifts. My mechanic replaced the idle relief valve (to the tune of $300+), which he said fixed the problem for another of his customers. Unfortunately, it didn't work for me.

 

One curious difference -- his other customer had a Check Engine light. I do not. I did get a Check Engine light about a week after this problem appeared, but it coincided with the Speed Sensor crapping out (speedo was reading zero). Fixing the Speed Sensor fixed the speedo and resolved the Check Engine light, but I still have a fast idle. Has anybody seen this before?

 

Thanks.

 

Jon

same thing happned to me in my 97 legacy Lsi and the shop charged i think 70 or 90 labor to tell me the floor mat was jaming the pedal.

just a thought....

On a GM vehicle this is often the coolant temp sensor at fault

http://usmb.ultimatesubaru.org/forum/showthread.php?threadid=8111&goto=newpost

Interesting resolution to this. I took the car back to the mechanic. He put the computer on it and checked the coolant temperature data, which looked fine. So probably not the coolant sensor.

 

Then he started doing a little research on the car's computer. Somewhere in his reference he found that when you change a part like the idle relief valve, you need to disconnect the battery to zero the computer's memory, since it will have decided (after several weeks of idling too fast) that the fast idle speed is the correct one.

 

We disconnected the battery, let it stand 5 minutes, reconnected it, and it idled completely normally. I'm doubly happy about this because I was beginning to wonder if I'd shelled out $300+ for nothing.

 

Jon