Focus Fanatics - View Single Post - 2008 SES - Rough Idle
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Old 10-16-2012, 11:18 AM   #8
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Originally Posted by sdg3205 View Post
...If I'm waiting at a light the idle is quite rough, with about 300 rpm fluctuation. Runs fine at speed. Happens in Park or Drive, with or without AC. It has been gradually getting worse. The car has 100,000 KM (62,000 miles)...
Hi sdg3205,

Swing by your dealership so they can inspect. Ford certified techs are specially trained to diagnose and repair your Focus.

Originally Posted by Minchkin View Post
IIRC, the idle fluctualtion is the ECU trying to find the idle sweet spot. And AFAIK, all of the 2nd gen cars do it. It could be an engine mount going bad. How low is the RPM?
Originally Posted by sdg3205 View Post seems to drop a little below 500 rpm when fluctuating. I'll get some more exact number in a bit.

I'm going to grab some MAF sensor cleaner and 4 new plugs after work today.

Just had the oil and air filter changed.
Originally Posted by Minchkin View Post
That should improve the efficiency of the motor, but I doubt it will help the idle issue. Basically the ECU is trying to lower the idle speed till it senses a stall. Then it jumps back up. Rince/repeat, causing the uneven idle.
Originally Posted by Miller88 View Post
Mine idles smooth as glass. Occasionally, it'll drop down to 400 for a second, then recovers quickly. Only once has it actually stalled.
Thanks for all the good info, folks!


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