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Discussion Starter · #1 ·
I have started having problems with my car for about a year now, on cold start the car revs to 2K rpm and will idle there until the car reaches operating temp and then it will settle down to about 750rpm. I know the car idling at 2,000 rpm every single time it starts cold will kill my motor eventually so I really need to fix it. I've played with my throttle body, replaced my temp sensor. Also, when I put it in gear it jerks really hard when the trans grabs but then it will also idle at 750 once in gear. The ambient temp does not affect it this will happen when it is -1 degrees F outside or 100 degrees F outside. This problem only occurs when the car is cold and the car is in park. It's an LX and it says under the hood "this car is equipped with automatic idle control" that my be the problem. Any help or insight would help a lot.
Also, very rarely, when the car is idling out of gear when hot, it will still idle at 2K rpm an the idle will just sit there and bounce from 1500 to 2k over and over again an the when I put it back in gear and back out of gear it stops.
 

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First check for vacuum and intake air leaks, if there are none.

It is the BAC/ISC valve on the back of the throttle body.
It has an electric valve to control idle and a temperature operated coolant valve (like a T-stat), the coolant operated valve opens when coolant is cool and closes when coolant is at operating temperature, to warm the engine faster.

The electric valve tries to maintain set idle but only has a 500 rpm range, when idle goes up and down 2000 - 1500 rpm thats the electric motor trying to adjust idle, the valve closes but idle is still to high so the ECU resets the valve and tries closing it again.

You need to remove the four machine screws holding it to the throttle body and clean all the backed oil build up out and see if that helps. - You will need a replacement gasket to reinstall it.

If that doesn't solve the problem you need to replace the valve.

My first LX 5speed had this problem but only in the winter, I drove it for many years like that without issues.
 

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Discussion Starter · #3 ·
First check for vacuum and intake air leaks, if there are none.

It is the BAC/ISC valve on the back of the throttle body.
It has an electric valve to control idle and a temperature operated coolant valve (like a T-stat), the coolant operated valve opens when coolant is cool and closes when coolant is at operating temperature, to warm the engine faster.

The electric valve tries to maintain set idle but only has a 500 rpm range, when idle goes up and down 2000 - 1500 rpm thats the electric motor trying to adjust idle, the valve closes but idle is still to high so the ECU resets the valve and tries closing it again.

You need to remove the four machine screws holding it to the throttle body and clean all the backed oil build up out and see if that helps. - You will need a replacement gasket to reinstall it.

If that doesn't solve the problem you need to replace the valve.

My first LX 5speed had this problem but only in the winter, I drove it for many years like that without issues.
Yeah that's what all my research has indicated as well, I will take it off and clean it and replace the vacuum line, bc the only ones on the internet are used, which probably won't be much better than what I already have. Thanks.
 
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