Put new i.a.c.,t.p.s. checked vac.lines all seem pliable no cracks.64000 miles, starts right up idles kinda high but when it starts to warm up idle picks up even more.Checked diagnosis readout by turning ignition 3 times 505 code still comes up for I.a.c.Does anyone have any ideas on what else may cause high idle? Driving me nuts! O yah,put a push toggle ignition in here's what I did. Can't find diagram right now I will explain in next post. Getting old timer!! Thanks

 

Unplug IAC valve, turn ignition on, check all four wires for voltage, two of them should be 12 volts. My bet: you don't find it. Probably need to replace PCM.

 

Checked that,so you saying that's the only possibility?

 

If you aren't getting power on two wires there, either the wiring is bad, or the PCM is. Check the wiring, if it's ok, PCM...... Yours will need to be flashed to the correct vin, otherwise, the ABS, and SRS will whine. (and not work.....)

 

How do I tell if a.b.s. isn't working.No a.b.s.warning.Forgive me but what is S.r.s. exactly? Thank You

 

There is a metal plate under the intake manifold. When the gasket for this plate starts to leak extra air is drawn in and the idle goes up. This is after the IAC so the IAC is not able to bring the idle down. The first test for this is to look down the throttle body and see if the bottom of the intake is oil coated. If it is then you'll need to pull the intake and replace the gasket under there.

 

That a bit of a leap when a vacuum leak will cause a high idle.

 

SRS is the airbags. Do you have two, or four wheel abs? (check for wires for wheel speed sensors in front. If they aren't there, 2 wheel abs, which pretty much sucks anyway. )

If he isn't getting control voltage to the IAC, then either the wiring, or the PCM is bad.

 

Yeah what he said about plenum gasket I know can be a problem,but I did check for block blowby and all set there.I think,will 2x check. I am starting to wonder if driver is cooked for i.a.c. in pcm. I am still waiting on reostat to finish the smoke machine I am constructing to double check all possible vac leaks. But like you said ecm might be the issue. Thank You for your help!

 

It isn't an unheard of failure..... (nother guy had his fail, then both following replacements had the same issue.... a third replacement from another company finally solved it. We suspected they just painted his PCM, and shipped it back to him.)

I wanna see pics of your smoke machine. That could be EXTREMELY useful.......