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Discussion Starter #1
Hello Gentlemen.

I have a 2012 Fiat 500 Sport. Getting some HEAVY misfiring, bucks while driving, feels like it'll die at idle sometimes. It dips down to 550 - 600 rpm but never stalls. Codes were first a cylinder 1 misfire. Then I cleared it, and every was fine for a couple days and I then I drove it a lot...

The day after it was back again pretty bad. Now it's cylinder 4 and a code for multiple misfires. I swapped coil 1 and 2 and inspected the plugs. Sprayed water around the air intake with no sluggishness. And now its still multiple misfires and cylinder 4 misfire, with no other codes. Any ideas?

I'm tempted to try the cam shaft position sensor for cost effectiveness and ease of access (snowy in Canada here). Also with no other codes I start to wonder if its a sensor related issue that hasn't fully conked out.
 

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Discussion Starter #2 (Edited)
Edit: If swapping coil 4 and 3 doesn't reveal itself, I might even try the MAF sensor first. I had no pending codes of cam position sensor but I had one for MAF (along with other codes like EGR and HO2 sensors).
 

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I had misfire once, it was diagnosed as a failing coil. Replaced the coil and all 4 plugs and have been good ever since. Plugs on our cars are *required* at the specified intervals.

You cannot go longer than the intervals.
 

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when you check your coils or swap them, also swap the plugs and inspect for wear. also important to check pcv o-ring. if the o-ring leaks, the oil can seep onto ignition coils and soften the boots as well as the spark plug tube gaskets and foul out the spark plugs
 

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Discussion Starter #5
So I swapped coil 3 and 4. Visual inspection was great. The PCV hosing was clean, no oil mess... But the only thing funny was plug 4 smelt of fuel and was full of dry carbon, probably from the misfiring.

Thanks for responding. Yeah, I'm still waiting for the misfire to throw a check engine light. I suspect it will be a coil, it happened quite often at a dealership I worked at. I would just like definite proof.
 

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ohm out the coils then. the outlier as far as resistance values will show itself as a bad coil, but in my experience it’s usually just aged plugs.
 

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Discussion Starter #7 (Edited)
Update, still waiting for check engine light to return.

Acid916, where it is intermittent, would the OHMs still be off in the coil if it's currently running fine? Also, I did try to get an Ohm's reading but the prongs wouldn't reach in together and read it well. I don't have the right electrical diagnostic tools.

And new plugs went in summer of 2017, ran beautiful. All the plugs looked fine except cylinder 4 with the misfire. Dry carbon soot and smelt of fuel. Its running fine today, still waiting for misfire to return.
 

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post pictures of the plugs. if you dont have the right tools and experience back probing connectors, please dont because you could do more harm than good. i usually use tiny aligator clips attached to my fluke leads when ohming male ends. and yes, even being intermittent the resistance values of the coils will be different. im not at the shop right now but i might be able to find a coil to use as a baseline for desired resistance value
 

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Discussion Starter #10 (Edited)
45 thousand kilometers 2012 Fiat 500 Sport. 1.4L MultiAir. I'm too lazy to post the pictures of the spark plugs ( 1 and 2 were inspected) but from my experience they don't look abnormal. Just cylinder 4 plug was black sooty all around the tip and electrode and smelt strong of fuel.

Yeah, I could check the resistance with alligator clips.. Never thought of that. I'm still waiting for the misfire to happen. It might happen now that we're getting a cold snap in the next couple days. If they code stays on cylinder 4 then I'll be in for some digging. I have an app on my phone that can watch fuel trims so I'll watch those if it happens again and no other codes arise.
 

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Ive had a hesitation (after 3k rpm) on my 14' 500L, dealer replaced 1 coil & all the plugs, good for a few days then hesitation came back. A fee weeks later of hesitation they changed the remaining 3 coils yesterday & hesitation is gone. Hope it stays gone.
I never got a code for misfire but computer was looking into it. I could barely pass cars on highway

Sent from my SM-G930V using Tapatalk
 

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I have a similar issue with my 2012 Sport ATX. However mine is only apparent with a cold start. So far if the temp is below freezing the car sounds terrible and has thrown either the cylinder #2 misfire or multiple cylinder misfire codes. The other day it ran for a bit while I was letting it warm up and it died (didn't throw a code though). One coil and all 4 spark plugs were replaced less than 6 months ago when I bought the vehicle.

I know there is a cold start TSB, but that doesn't sound like it applies to my situation. Once its warmed up and has been driven around there are usually no issues....

Please post back if you discover a cure...
 

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Saw a neat video on YouTube about checking coil packs due to misfire/rough running engine.
Instead of swapping coil packs what the guy did was remove the coil pack hold down screw on each cylinder. Then simply pulled the coil pack up off of the plug and put it back down. If the engine stumbled worse or stalled, it wasn't the problem coil. When he got to the one that didn't cause a change in idle, he knew that was the one that was malfunctioning. Thought it was a neat alternative solution to attempting to diagnose a misfire by swapping coils.
 

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Saw a neat video on YouTube about checking coil packs due to misfire/rough running engine.
Instead of swapping coil packs what the guy did was remove the coil pack hold down screw on each cylinder. Then simply pulled the coil pack up off of the plug and put it back down. If the engine stumbled worse or stalled, it wasn't the problem coil. When he got to the one that didn't cause a change in idle, he knew that was the one that was malfunctioning. Thought it was a neat alternative solution to attempting to diagnose a misfire by swapping coils.
Any danger of getting a nice shock when doing that?

tEdolph
 

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I’m having this same issue with my 2012 fiat 500 abarth with around 80k miles. Cylinder 2 and 3 misfire and codes for multiple cylinders. Car sputters a lot at idle and struggles to get going at times. How were you able to fix yours?
I have a similar issue with my 2012 Sport ATX. However mine is only apparent with a cold start. So far if the temp is below freezing the car sounds terrible and has thrown either the cylinder #2 misfire or multiple cylinder misfire codes. The other day it ran for a bit while I was letting it warm up and it died (didn't throw a code though). One coil and all 4 spark plugs were replaced less than 6 months ago when I bought the vehicle.

I know there is a cold start TSB, but that doesn't sound like it applies to my situation. Once its warmed up and has been driven around there are usually no issues....

Please post back if you discover a cure...
 
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