97 talon esi 420a nvt350
since i got my car it idled around 2-3k rpm, i changed the tranny over the weekend and now its idling at around 4-5k rpm, i changed the whole throttle body complete with the sensors. didnt make any difference. Its showing p0138 witch is Oxygen Sensor Circuit High Voltage (Bank1, Sensor2)I can also hear a vaccume leak aswell but i am having trouble finding it. Could the o2 sensor possibly cause this problem? if so witch sensor is it?

its most likely the vacuum leak. Light up a cig, blow smoke in the bay and look for movement. Its the easiest way I've found (well except finding someone to light a cig, I dont smoke)

No. You have a vacuum leak somewhere. Start the car and blow smoke around the intake manifold, and look for it being sucked in somewhere. The problem is most likely your upper or lower intake manifold gasket, throttle body gasket, or fuel injector o-rings. Just look where the smoke gets sucked in, and that's where your problem is.

Good luck.

Originally posted by adamzty
No. You have a vacuum leak somewhere. Start the car and blow smoke around the intake manifold, and look for it being sucked in somewhere. The problem is most likely your upper or lower intake manifold gasket, throttle body gasket, or fuel injector o-rings. Just look where the smoke gets sucked in, and that's where your problem is. Good luck.

Or use carb cleaner around those areas (one at a time), idle will change if it gets sucked in.

thanks guys, ill try that, im thinking it might be a mmaifold gasket, i checked it out some more today, and i unhooked all the vac lines and plugged them with my fingers and it didnt make a difference. i took the intake tube off and put my hand firmly over the t.b. and it only dropped 200-300rpm. i got a new code today, p1494..witch is evap switch fault(or something of the sort) ihave no idea what evap is for besides something to do with emmissions.

I have an issue somewhat like this, so thought I should post here instead of making a new thread.

My RS idles at about 1500-2000 rpm normally. Now I found something that might be relevant in tryign to diagnose my issue. If I turn on the AC it idles at 1000rpm. The rpms are also slow to drop.

I am going to clean out the IAC today. I had this issue before and it turned out to be the TB gasket, but I made sure it's not that this time. Any suggestions appreciated.

Could be a bad IAC. Mine went bad wide open, sounded like a massive vacuum leak, idled at 4k. Took the IAC out and plugged it in, turned key on, didnt move. New one fixed idle.