93 1UZ Idle motor checking?

[GSMnow]

My freshly running 1UZ Celica is having one problem. It does not have a cold high idle. It fires up fine, but will die unless you put your foot on the gas a bit to keep the revs up. Once it is holding fairly steady, you can lift your foot and it will stay running, but at just 450 rpm or so until it warms up at which point it idles at 650 or so and seems just fine. From the diagrams I have it looks like the only cold idle speed control is the 6 wire stepper motor at the front of the plenum. Is it common for these to clog or freeze up? Is there any easy way to test it? I know some ECU's have a test mode that runs the motors up and back, can the 93 1UZ do this? Unfortunately, the car and books are still far away from me, and I am trying to direct a friend on how to check and repair this problem. This is one of the very few things keeping the car from going to the emissions test.

Thanks for any help

Gary M.
1983 Celica 4000GT-S (93 1UZ power)

 

[Zuffen]

From your description I'd suspect the cold start circuit.

It idles bad cold but good hot.

 

[jibbby]

Check the TPS Sensor, it could be failing...

 

[GSMnow]

As far as I can tell the cold start injector system is working fine. It fires off on just a touch of the key. The volt and ohm readings in the Lexus book check out for the cold start injector, and I think it only fires during cranking when dead cold. So I don't think that is the issue. The TPS sensor all checks good as well. The idle switch is closed, and opens just a little off of the stop screw. The TPS wiper is a nice smooth climb in voltage with opening throttle. It is about .6 volts at idle and 4.3 volts at wide open. I don't think it is getting full open from the pedal, but that is not a big deal.

The ohm checks of the idle air motor also check fine. I also have battery voltage at the correct connector pins. I think it is just plain stuck and not able to move. If we don't find anything else wrong, we will just pull off the idle motor and see if it moves. My friend (the one 2500 miles away with the car) is searching the books for a test mode to make the motor move. I will post back if we find anything. I jusy hate tracing things from 2500 miles away.

Gary M.