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93 Es300 Won't Idle Cold After Iac Cleaning And Replacement

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I have a 93 es300 that will not idle when cold. I have meticulously cleaned the IAC valve and it operates smoothly. If the valve is inserted back onto the throttle body in the open position, the car idles immediately upon startup and will be fine until it is shut off again. The service manual states there should be a clicking noise upon shutoff from the IAC valve and I can hear this from a hose that I put on it and to my ear for clarity. When I pull the IAC valve off again, it is in the closed position. I got a replacement from a salvage yard, it came off of the old engine in the open position and that is how I installed it. The engine fired right up, but after shutting it off again, it failed to start without help from the accelerator. When I took it off, it was in the closed position. I haven't put battery power to the connector terminals to see the valve operate, but it seems too much of a coincident that the two act alike. I feel the engine is starving for air but I don't know how to diagnose it. I don't have money to throw at all the possibilities. When the temp gauge moves up, the car starts and idles fine. It's frustrating to only see iac cleaning advice and not much else for my situation. Hoses are mostly new and all seem good. No CEL. Any suggestions would be greatly appreciated.

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I have a 93 es300 that will not idle when cold. I have meticulously cleaned the IAC valve and it operates smoothly. If the valve is inserted back onto the throttle body in the open position, the car idles immediately upon startup and will be fine until it is shut off again. The service manual states there should be a clicking noise upon shutoff from the IAC valve and I can hear this from a hose that I put on it and to my ear for clarity. When I pull the IAC valve off again, it is in the closed position. I got a replacement from a salvage yard, it came off of the old engine in the open position and that is how I installed it. The engine fired right up, but after shutting it off again, it failed to start without help from the accelerator. When I took it off, it was in the closed position. I haven't put battery power to the connector terminals to see the valve operate, but it seems too much of a coincident that the two act alike. I feel the engine is starving for air but I don't know how to diagnose it. I don't have money to throw at all the possibilities. When the temp gauge moves up, the car starts and idles fine. It's frustrating to only see iac cleaning advice and not much else for my situation. Hoses are mostly new and all seem good. No CEL. Any suggestions would be greatly appreciated.

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More than likely you're needing to readapt idle strategy. You'll need to hold the throttle open until it warms up. After it warms up you'll need to shift into gear and and back into park several times - also turn the A/C on and off several times and take notice as to whether or not the idle control device is attempting to compensate for load. If it doesn't then you'll need to take a digital multimeter and make sure you have continuity between the terminals of that connector and the appropriate connector of the ECM (behind the glove box) if all relative wires have continuity then you'll need to try another ECM...if they don't then you'll need to find the wire(s) that are broken and that could have happened when valve cover gaskets were done or maybe the motor was replaced once? Regardless...

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More than likely you're needing to readapt idle strategy. You'll need to hold the throttle open until it warms up. After it warms up you'll need to shift into gear and and back into park several times - also turn the A/C on and off several times and take notice as to whether or not the idle control device is attempting to compensate for load. If it doesn't then you'll need to take a digital multimeter and make sure you have continuity between the terminals of that connector and the appropriate connector of the ECM (behind the glove box) if all relative wires have continuity then you'll need to try another ECM...if they don't then you'll need to find the wire(s) that are broken and that could have happened when valve cover gaskets were done or maybe the motor was replaced once? Regardless...

Thanks for the reply Sparkybouy, I'll check into that. I have done the A/C thing and driven the car and I think the idle is lower than it should be but it still idles. I'll do the continuity check and hopefully find something. This is a fairly recent replacement ECU installed by the local Lexus dealer although it was a used part. I was hoping to find an easy solution because the other issue this car has is that the transmission needs rebuilding/replacement. I can drive it now, but must shift manually through the gears. I've replaced this car and am wanting to sell it. I've got a lot of money invested in parts in this car and it should be a good car for someone after they solve the tranny situation.

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I had same trans problem, it ended up being 2 trans. solenoids $1100 bucks- but shifts like new and has 260k miles now.

Also cleaned my idle control with no results- I manually turned up the idle via allen key..for temporary fix....

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