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Discussion Starter · #1 ·
I am having a misfire on the cold start. I changed the plugs and couls and was ok for a couple days and now misfire again on start. Could this be a dirty air intake sensor? Or more serious
 

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I am having a misfire on the cold start. I changed the plugs and couls and was ok for a couple days and now misfire again on start. Could this be a dirty air intake sensor? Or more serious
The only sensor on the intake is a temp sensor. These cars do not have a traditional mass air sensor like the GT or V6 Mustangs do. It's doubtful that a dirty intake temp sensor could cause a misfire on cold start. Now a dirty air filter could definitely cause misfiring.
 

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Pretty common to have a misfire on these motors on cold start. Most likely not your air filter. Ford had a PCM reflash for these cars after the first few model years for the computer as to not trip a code on cold start misfires. That being said a few things to watch out for.

Are you loosing coolant? The head gasket has been known to weep from cylinder flex, it will start to leak coolant into the cylinders once the car is cooled off, once warmed up everything swells a bit and usually wont be leaking under operating temp until all the sealing material on the metal gasket is worn away.

You also said you changed the plugs, are they gapped properly?
 

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Monitor your coolant level in the bottle. If it drops it's a sign that your headgasket is going out. I had this exact scenario happen last summer.
 

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I just went through this myself. Owned the car for all of 2 weeks before experiencing misfire on cold starts and it slowly got worse over the course of a week. Coolant level was dropping as well. Set your phone up to record your exhaust on cold starts and see if t smokes. I didn't think mine did until I recorded it from behind the car. Took it in thinking it would be a simple head gasket replacement since it wasn't that bad and I was still driving it moderately. 2 months later and I have it back from Ford with a new longblock.
 

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Discussion Starter · #7 ·
I just went through this myself. Owned the car for all of 2 weeks before experiencing misfire on cold starts and it slowly got worse over the course of a week. Coolant level was dropping as well. Set your phone up to record your exhaust on cold starts and see if t smokes. I didn't think mine did until I recorded it from behind the car. Took it in thinking it would be a simple head gasket replacement since it wasn't that bad and I was still driving it moderately. 2 months later and I have it back from Ford with a new longblock.


thats what it has come too. I think i drove on it for a couple weeks like that but mine is on, off, misfire days and I finally noticed coolant levels were down. Its parked now ready to go to ford. Thanks for the info was the repair covered by warranty?
 

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Mine wasn't covered, but my car was heavily modified and the dealer(s) didn't want to have to defend the warranty repair to Ford if it were questioned. A lot of it is going to depend on your modifications and on your dealer. Good Luck.
 

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intake, pipes, Intercooler, exhaust, wastegate, BOV, pro-tune, etc... Nothing out of the ordinary, but I have made every effort to make sure my mods both perform and look good. To the dealer that apparently means nothing is warranty covered anymore...
 

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Mine got exactly the same issue. Started around 40K miles, now at 45K miles and got worse, loosing 1/2 qt of coolant a week. I've told it's a head gasket, does it worth the job or better get a new engine?
 

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Mine got exactly the same issue. Started around 40K miles, now at 45K miles and got worse, loosing 1/2 qt of coolant a week. I've told it's a head gasket, does it worth the job or better get a new engine?
If you have the money it wouldn't be a bad thing especially if you plan to make big power down the road. If you are keeping stock or lightly modded power levels then it's probably best to just replace the head gasket.
 

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I live in Israel, bringing an engine from US is quite a costly thing. I'd replace the gasket, the question is this engine reliable enough to stop making troubles after gasket job... WDYT?
 

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I live in Israel, bringing an engine from US is quite a costly thing. I'd replace the gasket, the question is this engine reliable enough to stop making troubles after gasket job... WDYT?
I've hit 67k miles on my engine with no head gasket issues. You might have had a bad luck case with your engine. These 2.3l engines are quite reliable if well maintained. The Focus RS had gasket issues only because Ford was accidentally putting Mustang gaskets in the RS engines. I think if you put a new head gasket in the engine provided everything else is fine then you should be good still.
 

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Discussion Starter · #16 ·
Mine got exactly the same issue. Started around 40K miles, now at 45K miles and got worse, loosing 1/2 qt of coolant a week. I've told it's a head gasket, does it worth the job or better get a new engine?
Have you gotten it fixed yet?
 

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If your block and head are still true, I'd recommend an aftermarket head gasket along with ARP studs asap. As long as everything else is still ok, not worth swapping the entire motor.
 

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I've hit 67k miles on my engine with no head gasket issues. You might have had a bad luck case with your engine. These 2.3l engines are quite reliable if well maintained. The Focus RS had gasket issues only because Ford was accidentally putting Mustang gaskets in the RS engines. I think if you put a new head gasket in the engine provided everything else is fine then you should be good still.
I believe the OEM head gasket was also revised in 2017. The RS/Mustang gasket issue happened, but from what I've gathered, there were also issues with the early (15-16) S550 ecoboost gaskets. I came across a Tune+ post/thread detailing all of it about a month ago.
 

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I believe the OEM head gasket was also revised in 2017. The RS/Mustang gasket issue happened, but from what I've gathered, there were also issues with the early (15-16) S550 ecoboost gaskets. I came across a Tune+ post/thread detailing all of it about a month ago.
That's news to me about the Mustang gasket issue. Of course I have a 17 Eco and haven't had any issues besides some bad O2 sensors.
 

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Discussion Starter · #20 ·
I believe the OEM head gasket was also revised in 2017. The RS/Mustang gasket issue happened, but from what I've gathered, there were also issues with the early (15-16) S550 ecoboost gaskets. I came across a Tune+ post/thread detailing all of it about a month ago.
Haven't missed any oil changes air filter changed hopefully can repair not replace hole motor
 
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