Idle Control Malfunction and Knock Sensor. Cause and Effect? -

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Old 05-02-2010, 05:12 PM
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Join Date: May 2010
Posts: 2
Default Idle Control Malfunction and Knock Sensor. Cause and Effect?

I'm new so sorry if I missed something, I tried to search first. I have a 2000 Civic EX, 1.6L VTEC. I'm throwing two codes, Idle Control Malfunction and Knock Sensor.

Now, My car doesn't knock but I do have an idle issue. I'm assuming the idle problem causes the knock sensor to engage? But with my idle; when the car idles it seems to sit at a nice 1000-800. When you engage A/C,brakes or power steering though, the idle drops to 500-400 and sometimes will do it without stress in the first place. I've cleaned my throttle body and my IACV. What's the problem? We've also pulled my throttle cable the opposite way onto the bolt, to see if it sat too low. It doesn't because the idle wouldn't change when we tried to push it the opposite way.

Also, would having a knock sensor on engage safemode on my ECU? Because my VTEC seems non existent. I've heard it to be called "retard timing."

Is it a vacuum leak? Because that scenario scares me. It never dies, it just falls. Is it a gasket problem? I'm just looking for a path to take here.

Any help would be greatly appreciated.
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Old 05-02-2010, 08:01 PM
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Join Date: Jun 2007
Posts: 10,023

If the CEL is on for any reason the VTEC will not engage, and the engine will rev limit at about 5000. That is called "limp home" mode.

The problems you are experiencing are not related to each other though.

Probably your knock sensor is broken or disconnected. The ECU constantly checks it electrically even though the engine may not be knocking.

For idle problems start by checking the spark timing and bleeding the cooling system. If it's not that, try opening the air screw on the throttle body to keep idle up while the A/C is on. On the VTEC with horizontal throttle body it should be on the top front near where the big hose from the air cleaner attaches.
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Old 05-02-2010, 08:38 PM
Junior Member
Join Date: May 2010
Posts: 2

My rev doesn't limit though, it runs open till red. Which is where someone told me safemode, that it just wacks my timing to save the engine from possible rod destruction.
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