Rough Idle - 2008 Ford Focus

Hi all,

I have a 2008 Ford Focus - 4 Door Sedan SE 60300 miles.

I’ve gone to 3 mechanics now and no one can seem to figure out whats wrong with my car. Here’s whats happening:

About 1 1/2 years ago I took my car to get an oil change at Jiffy Lube (Yeah never again). When I left, my car was idling funny… Silly me didn’t take it right back and have them tell me what was wrong… so I let it go, well about a month later it started idling even weirder. Basically it feels like my car is shaking when it gets under 1000 RPM and I notice my RPM dial start falling and bouncing back, acting like its going to stall, but never does. I notice a loss of power when this is happening (on speed up and just accelerating in general). All of this is random, I can’t seem to put a pattern to it as to when it happens. One day I’ll start it up and everything is perfect… Then I’ll shut it off and restart it later, and it starts vibrating and puttering again… No signals as to if its hot/cold or wet/dry, no environmental variables seem to cause it to happen anymore than others. And there is no check engine light on, everything “looks” normal.

What I’ve had done to it so far is:
Air filter changed / reseated
3 oil changes (keep getting told it will “help”)
Throttle cleaned
Computer reset for idle sensor data rebuilding

Now I’m told that I need new engine mounts, and that could be the reason for the vibration. I’m thinking that the vibration caused the mounts to wear out, more so than the mounts being the cause. Mainly because I don’t see how bad mounts could cause loss in power/bad idling.

Anyone have any idea what could be wrong?!? Really bugging me and don’t want to keep throwing money at it for phantom solutions. Seems like mechanics I go to can’t figure it out unless there is a check engine light on with some diagnosis code to tell them exactly whats wrong.

Thanks for the help!

You say you’ve had in the hands of 3 different people. Other than the minor little service items you listed what have these people done? Checked fuel pressure? Check plugs & wires? (Are those the original plugs? What does the owner’s manual say about the service interval on them?). Clean the MAF sensor? Check for vacuum leaks? Is or has the check engine light been on? Have error codes ever been pulled and, if so, what were they? Has anyone ever put it on scantool too check out things like the fuel trim?

In short, provide all of the info to have about past diagnostics and about the car’s maintenance history or the answer could just be “anything could be wrong.” At this point I am going to assume that the Jiffy Lube incident is a coincidence and unrelated.

cigroller, I am on the same page, and thinking with this year of car, something obvious is being overlooked. Could be a connector, vacuum hose, etc. Start simple and work your way up. I accept from the oil change something went bad, but I think it is an easy fix given the right mechanic.

My actual guess - devoid of any other info - is actually going to be an EGR system issue. So, now that I’ve said so, kboyd, find the vacuum line to your EGR valve. Pull it off & plug it (usually about a golf tee size) and cap the valve. See if that makes a difference. (This will turn on a check engine light & set an EGR code & is not permanent. It will just tell you if the EGR system is the problem).

Cigroller, that’s all they did to it, I wasn’t about to spend a lot of money to have it fixed unless the smaller stuff was done. Really not sure why they didn’t try all the stuff you guys mentioned, but I as insistant on knowing what they were checking just so the next time it won’t be repeated… No, the check engine light has never been on, just rough idle and loss of power. That’s all. What I put up there is all that I’ve had done to it since the initial problem started… Soon as I get home tonight I’ll try the EGR and see what happens… So if I do this it theoretically should just run normal if it is, in fact, the true problem? Really getting frustrated with the mechanics I’ve seen at this point lol

Without any check engine light to provide error codes then you just need to do the basics, and if that means paying people for labor time/expertise then that’s what you have to do.

You do need a good, locally owned, independent mechanic - someone who specializes in diagnosing and fixing car problems - rather than a national chain store that mostly offers pre-set “menus” of services rather than expertise.

You need to:

  • Have spark plugs & wires inspected & replaced if necessary
  • Have it checked for vacuum leaks - for which knowledge of using a vacuum gauge would be helpful.
  • Have the fuel pressure checked, including under load
  • Have your MAF sensor cleaned (easy to do yourself)
  • Clean the idle air control valve (might be easy to do yourself).
  • The EGR thing is also easy to do, and yes, if you pull the vacuum line from the EGR and have no further troubles, then it tells you that it is an EGR system problem.

I’m sure others might add to that list. Its all just very basic testing/maintenance stuff.

Yeah, sorry I didn’t mean to sound like I wasn’t willing to pay… I just didn’t want them to go through and tear the engine apart without doing the basic stuff first and was mainly referring to the one guy saying that they wanted to replace my engine mounts to “fix” the problem, just doesn’t seem like the cause at all

2 of the 3 have been local independently owned shops. Just surprised they haven’t gone through these same steps… I looked under the Maintenance Files here and think I’m going to pick one from that list instead of randomly trying “friend of friends” shops. Seems like there are a few very highly rated people near where I live. I’ll have that list handy, just so I can specifically have them look at those items. Thanks Cigroller

Try getting some used parts at a local car parts yard.

Maybe an idle air control valve, mass airflow sensor, throttle position sensor (or the whole throttle body!).

Parts are cheap. Labor… well we know what that costs. maybe you should try and find a local person through FSWERKS or FOCUSFANATICS web forum. Some people on there are really helpful and its a forum only for ford focus people - and they have a buy sell trade section where you could post something saying you are looking for “lots of sensors for a duratec engine / 2008 ford focus”

YOU CAN DO IT YOURSELF - or at least some of the easier things.

Get a repair manual for the car, chilton and haynes are popular. replace a few of the easy parts - and if it runs better / worse, note it.

If I had to check one thing on this car it would be the PCV valve, the quick lube folks always check the PCV valve… but they may have damaged the hose or the O-ring.