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Ford Focus Rough Idle

2 Replies | Filed under Maintenance & Repairs, Ford, Focus

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DrBoost on October 19, 2009

It seems most folks with a Ford Focus live with a rough idle. They try replacing the spark plugs, spark plug wires, fuel filter and air filter to no avail. I'll be honest, 99% of the time when Ford Focus owners come to my shop to cure a rough idle, they need these things anyway and I'll try to sell the service because it's been neglected. Anyway, there are three things that I look at first. Almost every time ONE of these three is the culprit. I'll clean the MAF (Mass AirFlow) sensor. This is actually a maintenance item that get's neglected and should be done every year or two. While it's running rough I'll LIGHTLY tap the IAC (Idle Control Valve) to see if the idle changes for the better. If so, I'll either clean or replace the IAC (its mounted on the throttle body). Then if the rough idle is still there (usually is) I'll check EVERY vacuum hose under the hood. The hose that goes from the PCV valve (on the cam cover) down behind the engine develops a hole. If this hose feels gummy or oily, replace it and your idle will be as smooth as a Ford 4 cylinder can get.

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  • Reply to John | Flag
    John on November 12, 2009

    Check, check, and check. I have 2 Focus wagons with the 2.0 Zetec engine, an '02 and an '03. Both have this rough idle issue although the 03 is not as bad. On both cars the rough idle goes away when the engine has been thoroughly warmed up, but is definitely there before the engine reaches normal operating temp. Both cars have fresh air filters, fuel filters, & spark plugs. MAF's & throttle bodies have been cleaned. The 02 has new spark plug wires and the PCV vale and hose leading to it have been replaced.

  • Reply to DrBoost | Flag
    DrBoost on November 13, 2009

    I currently have a car I'm chasing the idle problem as well. I've done all the things I outlined and while the idle is much better, it's still not up to my standards. The one thing I have't done yet is look at the coil packs and plug wires.

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