Ford Focus misfiring....I think.
Discussion
My 2001 Ford Focus with a 2.0 Zetec engine is acting strangely, feels like it is developing a misfire around 2-3k rpm under load. My O/H came home once saying all the warning lights came on whilst driving and then went out again, like the engine had cut out and restarted.
Car is on 125k and in the last 20k it has had new plugs and a lambda sensor, plus regular servicing. There is a slight blow from the exhaust. Engine management light hasn't come on at all.
Any likely causes? Coil pack, leads, airflow sensor?
Car is on 125k and in the last 20k it has had new plugs and a lambda sensor, plus regular servicing. There is a slight blow from the exhaust. Engine management light hasn't come on at all.
Any likely causes? Coil pack, leads, airflow sensor?
Rickyy said:
My 2001 Ford Focus with a 2.0 Zetec engine is acting strangely, feels like it is developing a misfire around 2-3k rpm under load. My O/H came home once saying all the warning lights came on whilst driving and then went out again, like the engine had cut out and restarted.
Car is on 125k and in the last 20k it has had new plugs and a lambda sensor, plus regular servicing. There is a slight blow from the exhaust. Engine management light hasn't come on at all.
Any likely causes? Coil pack, leads, airflow sensor?
Sounds like your ignition leads rather than the ignition coil. If it was coil it would noticeably miss on idle. Car is on 125k and in the last 20k it has had new plugs and a lambda sensor, plus regular servicing. There is a slight blow from the exhaust. Engine management light hasn't come on at all.
Any likely causes? Coil pack, leads, airflow sensor?
Pull the recently changed spark plugs back out & see if there are any brown scorch marks around the white porcelain insulator of the spark plugs themselves.
If so, get yerself a set of decent ignition leads.
Pumaracing said:
Rickyy said:
Strangely enough I have a brand new fuel filter in a box for it, was meant to change it when I changed the oil and plugs but it started raining!
I'll give that a try this weekend!
You'll be wasting your time because it isn't that.I'll give that a try this weekend!
codpiece said:
Sounds like your ignition leads rather than the ignition coil. If it was coil it would noticeably miss on idle.
Not necessarily. Modern ECUs employ variable coil charging time to maximise spark strength across the rpm band. I've had plenty of cars with coilpacks which have idled perfectly smoothly, but misfired under load. More often than not, it's the resin packing around the coils that breaks down and cracks. The 40 odd KV coil output then finds a shorter path to ground.Not saying it isn't the leads, but I just know from previous experience working on Focuses the coilpack is usually the reason.
Nick1point9 said:
Pumaracing said:
Rickyy said:
Strangely enough I have a brand new fuel filter in a box for it, was meant to change it when I changed the oil and plugs but it started raining!
I'll give that a try this weekend!
You'll be wasting your time because it isn't that.I'll give that a try this weekend!
Where is the exhaust blow?
If it is pre lambda sensor it may be messing up your fuelling adaptions, resulting in lean/rich running and a misfire?
Alternatively, a misfire on load may point towards an ignition system "tracking" fault as the voltage required to ionise the spark gap increases with load (because, in laymans terms, there is more "stuff" in the way for the spark to break through). If something in the ignition system breaks down at a lower voltage the sparkplug won't fire. Old plug leads or crack ignition coils often do this (especially when warm)
If it is pre lambda sensor it may be messing up your fuelling adaptions, resulting in lean/rich running and a misfire?
Alternatively, a misfire on load may point towards an ignition system "tracking" fault as the voltage required to ionise the spark gap increases with load (because, in laymans terms, there is more "stuff" in the way for the spark to break through). If something in the ignition system breaks down at a lower voltage the sparkplug won't fire. Old plug leads or crack ignition coils often do this (especially when warm)
I had the middle section replaced recently, so I think the blow is towards the end of the exhaust system. The problem seems to have rectified itself for now! Not sure if it is likely to be related, but every now and then it takes quite a lot of cranking before it starts.
Will the ECU store fault codes even if the EML hasn't come on?
Will the ECU store fault codes even if the EML hasn't come on?
Don't know if you've sorted this one yet, but 99% this is an HT lead issue. Have seen quite a number of zetecs through the workshop with these symptoms. Coil packs do fail but you tend to lose a cylinder and the EML comes on. The extended cranking on start up is most likely unrelated, this is a bit of a Ford zetec/duratec characteristic, some do it and some don't.
It seems to be behaving atm, but I'll just replace the leads if the problem returns.
The cranking is a strange one, not too bothered though, its on 125k miles and slowly deteriorating around me, I'll be happy if it makes another 10K without huge bills.
Thankyou to everybody that has helped.
The cranking is a strange one, not too bothered though, its on 125k miles and slowly deteriorating around me, I'll be happy if it makes another 10K without huge bills.
Thankyou to everybody that has helped.
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