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Engine Misfires When Cold Only


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Just joined the forum and looking for some friendly advise as well as offering my advise on issues.

I've recently developed a problem with my Ford Focus Mk1, 2.0, 2001. Each time I attempt to start my focus when the engine is cold it misfires several times, then once I've hit the gas and try again it starts. Sometimes it will start first time but it feels like the engine is struggling. If I switch off the engine when its warm and switch back on again, it will start first time no problem. Also I've had no issues when the engine is idle too.

I've changed the battery, spark plugs (gapped correctly) and voltage checked the HT leads but to no avail. I'm thinking it might be a fuel problem, could it be the fuel filter as I know this needs changing? Also when I took the old spark plugs out they looked black at the spark end, could the rich mixture be an issue? I've done just under 90k mileage.



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Thanks, No lights on the dash, however I will change my fuel filter as its long overdue and try using fuel injector cleaner. I've done some looking around and found that it could be the cylinder head temperature sensor. The CHT sensor sends signals to the ECU, if the sensor is faulty and thus sends incorrect , or no info to the ecu as above, the fuel and air mixture will be incorrect and thus do as you describe resulting in poor running and no start situations temp dependent. Has anyone experienced this?

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Thanks for the replies guys. My Focus is starting first time now. It turned out to be the CHT sensor as suspected which I replaced, however I had to remove the alternator to get to it which was a beast to take off, but managed to do so after hours of graft. Also cleaned up the throttle body housing which looked dirty too!

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