high rough idle on 98 2.5 dohc

[jim milewski]

After head gasket replace and fixing the camshaft oil seal I have a high and rough idle, I have code 1507, (idle control system malfunction) and 0507 (high RPM at idle) also it won't go into closed loop, I did have a bad heater circuit code but it's out now, I think it's just a matter of time until it comes back. With the high idle I unpluged the IAC connector and no change, I sprayed WD 40 around the intake looking for a change indicating an intake leak but found nothing. The voltage at the O2 sensor is right around .3 volts. Is there a diagram availabe for vacuum hoses, is there an idle adjustment, is the TPS the device with a black cover and slots where the screws go through so you can vary it a few degrees and the IAC right near it both on the passenger side of the intake, both have three wires, is there any wiring and connection diagrams available for this section. Any help appreciated, I'm almost there after this top end rebuild, thanks

[Fairtax4me]

Check the adjustment of your throttle cable before digging into other things.

 

The TPS is on the side of the throttle body opposite the throttle levers. It's either brown or black, don't worry about that unless you get a code for it.

 

The IAC is the dohickie stuck to the passenger side of the intake manifold. They get stuck sometimes, but can be cleaned pretty easily. The gasket is like $5 from the dealer. Remove the valve and spray it out with air intake cleaner. Wiggle the paddle inside it to free it up and spray some more. Re-install with new gasket.

 

Heater circuit is a code for one of the O2 sensors. Just check the wiring to those to make sure they are plugged in tight. If it comes back again you might need a new O2 sensor.

[jim milewski]

thanks, I did find out (the hard way) on my own a little more about the IAC valve before reading up much on it, taking off the two philips head screws thinking that part was the whole valve and grabbing the soft round magnet with pliers to pull it up thinking it was a plunger then crushing the magnet into several pieces, found one on ebay for $47, the kicker is that I think mine was ok because it spun freely after I got the complete valve out. As for the O2 sensor I found one of the three wires pulled out, but after putting it back in still will not go into closed loop operation, there is an ohm or two across the heater element so that appears good, or at least tests good, the heater element does receive 12 volts so that part is good as well. I did the cable first and the throttle does bottom out against the stop, also reset the computer quite a few times, this is a definite learning experience! First time I ever pulled an engine from a car, I'm really getting attached to this Forester!