2010 Ford Focus SE Rough/Hunting Idle

[dkinter]

I purchased a 2010 Ford Focus SE with 45,000 miles on it. Since I bought it, I've put around 10,000 miles on it. It gets 30+ mpg, runs and cruises great, and fits the whole family without issue. The only problem with it is that it has a rough/hunting idle since I got it. It only hunts 50-75 RPM's. It doesn't stall, and I don't feel an issue when cruising. The vibrations are noticeable while at a stop whether in gear, parked, or neutral. There is no check engine light and it is not throwing any codes.

I have replaced the plugs, cleaned the MAF, removed and cleaned the entire throttle body, changed the oil(Full synthetic mobil 1 is my preference), air filter, and oil filter, and lastly checked the rear engine roll restrictor for debris(there was none).

I am at a loss. What could be causing this hunting idle? With this car being only a few years old I doubt it is a vacuum leak.

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[Kodyston]

Originally Posted by dkinter

I purchased a 2010 Ford Focus SE with 45,000 miles on it. Since I bought it, I've put around 10,000 miles on it. It gets 30+ mpg, runs and cruises great, and fits the whole family without issue. The only problem with it is that it has a rough/hunting idle since I got it. It only hunts 50-75 RPM's. It doesn't stall, and I don't feel an issue when cruising. The vibrations are noticeable while at a stop whether in gear, parked, or neutral. There is no check engine light and it is not throwing any codes.

I have replaced the plugs, cleaned the MAF, removed and cleaned the entire throttle body, changed the oil(Full synthetic mobil 1 is my preference), air filter, and oil filter, and lastly checked the rear engine roll restrictor for debris(there was none).

I am at a loss. What could be causing this hunting idle? With this car being only a few years old I doubt it is a vacuum leak.

Mine jumps around a little too. Mine is a little older then yours but I'd say it's normal. How much does the car shake at idle? and does it kinda shake when your driving it too? Could be a motor mount going out or something. And always check the easy stuff. I doubt you have a vacuum leak too but a hose could have popped off just enough to let some air in/out. I'd just crawl up under it and check everything out and make sure everything looks like it's supposed to be there and make sure your wires and plugs are snug and connected well enough. Let us know what you find.

[dkinter]

All wires are good and tight. Dielectric grease applied to the proper areas. Plugs are OEM and gapped to OEM specifications. I'm out to sea at the moment and get home Tuesday so I will check on the vacuum hoses. Trying to do some research because it's starting to bug me and I'd like to find the solution.

I read a suggestion for a similar issue that leaned toward the EGR system. I'll unplug the vacuum to it when I get home and see if it clears up. If it does, I may have to get a new solenoid or some such. If anyone else has any ideas or input I'd appreciate it.