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Rough Idle


17togo

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My 2008 Focus with 40480 miles on it is having a rough idle issue, any thoughts before I take it in on what to look for? My mileage is great, averages about 38. I have a K&N air filter and it has been cleaned. I run Chevron Techron every 3000 miles. I am at a loss.

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Check the connector to the MAF sensor and verify it is secure (see pics below). Also, try cleaning the MAF sensor itself using a quick dry cleaning solvent for electronics (see here for details); this may be helpful given that the K&N air filter you're using is oiled.

 

PZEV:

08_foc_pzev.JPG

 

NON-PZEV:

08_foc_non_pzev.JPG

 

Thanks I will try that tomorrow 1st thing after church.

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  • 2 weeks later...

This may be a stretch, but have you checked the spark plugs? I understand if you do a lot of start-ups, the plugs could go sooner than expected. Had a Mystique whose plugs had to be changed at about 45K miles.

 

The only other thing I can think of is if you're running some accessories that are creating more of a drain.

 

Good luck!

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The Idle Air Control Valve could partially be sticking closed, preventing the proper air/fuel mixture when the engine is running cold. I had this issue with my '05, except the valve was stuck completely closed until the engine would warm up to operating temps. I had to sit there in park with my foot on the gas until the engine warmed up until I could drop it into gear, lest it would stall. I think this is one option that is worth exploring. Good luck!

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His Focus doesn't have an idle control valve. I doubt its the plugs, they're irridium and very expencive. I thought the interval was actually 105,000. Does the car feel shaky at idle or buzzy/vibrating. If its a shaky idle I'm surprised your engine light isn't on. The eltronic monitors on today's cars are very touchy, so I really doubt its a sensor, a misfire, or anything like that. If its buzzy/vibrating feeling you probably have an engine or transmission mount issue and the service center might put a couple different ones on before they get it fixed. Just be patient with them unless they're really screwing you around. Also ask them for the latest and greatest pcm software update. There are some various issues with the software that have been revised like weird engine light codes and such.

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  • 9 months later...

His Focus doesn't have an idle control valve. I doubt its the plugs, they're irridium and very expencive. I thought the interval was actually 105,000. Does the car feel shaky at idle or buzzy/vibrating. If its a shaky idle I'm surprised your engine light isn't on. The eltronic monitors on today's cars are very touchy, so I really doubt its a sensor, a misfire, or anything like that. If its buzzy/vibrating feeling you probably have an engine or transmission mount issue and the service center might put a couple different ones on before they get it fixed. Just be patient with them unless they're really screwing you around. Also ask them for the latest and greatest pcm software update. There are some various issues with the software that have been revised like weird engine light codes and such.

 

Update: Car now has 63000 miles on it and it is worse than ever. I found a tsb on this issue that stated it was covered to 80000 miles so I took it in and had it checked out. The dealer ran a two hour test and said I don't have the issue covered in the tsb. I know I do though cause it says on the tsb the car flutuates between 700 and 500 rpms, and mine does that at every light. Still considering changing plugs I don't know what to think.

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  • 6 months later...

Update, finally at 73000 miles on a 75000 mile warranty, I was able to find a dealer who was able to fix problem. It was the passenger side motor mount. I had it check at another dealer, they said it was ok, took to a dealer in Louisville and they diagnosed and repaired it in less than a day.

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