Hey everyone, for the past month, my Volvo wagon has decided to start idling really high, then back down to normal, then high again, then normal, at seemingly random times. Sometimes Ill start the car and it will idle smoothly, sometimes it will be idling fast and then mellow out whenever it feels like it, before idling high again. Lately its been idling real high, like Im putting my foot on the gas or something.

I thought it was the vacuum line that runs into the firewall and controls the vents, because the line was cracked, but I replaced it today, and its still doing it.

Any advice?

-Adam

 

It might be the Throttle position sensor switch. I'm dealing with a similiar problem and the car threw a 1-3-3 code. Pull your codes and see if you have something similiar. I have an 89 740. I have a code reader in the driverside corner of the engine compartment above the struts. You might have one as well.

 

Clean the throttle body and check to see if the control cable is stuck slightly when the throttle should be fully closed.