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Q: Revs low when idle and falls when at traffic lights

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Hi my focus revs are on about 700 when idle and when driving the revs are not as high as they were i.e. When in 4th gear the revs are on about 1200,also when I pull up at traffic lights the revs drop down to about 700 I have cleaned the idl control valve and disconnected the battery but it has made no difference could you please advise me on what it could be Thank you

My car has 77000 miles.
My car has a manual transmission.

A: Hey there. Even though you've cleaned t...

Hey there. Even though you've cleaned the idle air control valve, that doesn't guarantee that the valve isn't still sticking or otherwise malfunctioning. You could try very gently tapping on the valve and see if that affects engine speed. The solenoid in the valve can also be tested and a bi-directional scan tool can be used to try to command operation of the valve to see if it is functioning properly. Other possible causes of the problem you are experiencing are vacuum leaks, a faulty fuel pump, low fuel pressure, clogged fuel filer or clogged fuel injectors. If you would like to have this diagnosed, a certified professional from YourMechanic can come to your car's location to inspect the rough idle so that this can be corrected.

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