2012 CX-5 SkyActiv 2.0 AWD Misfire

Hi all, new member here.

I have a 2012 2.0L Auto CX-5 with 73k miles, dealer maintained from the beginning with all suggested jobs done. 3k miles ago, I realized a major increase in fuel consumption (I was used to drive 450kms with 50 liters, that dropped to 350kms with 50 liters in similar conditions) and hesitation (no vibration, but something like a minor power loss) under load, so dealer suggested to change spark plugs since it was not in stock at last maintenance. I have waited 2 weeks for plugs to arrive without a warning code, but one day I was on the highway, car started to vibrate, lost all power, CEL came on with SBCS and other warnings. The car was towed to the dealer, and they have changed the spark plugs with OEM ones (with Mazda logo). The failing cylinder's (no 2) spark plug was too dark and dirty with carbon compared to the others. I have done nearly 2.5k miles with the new plugs, no error codes or lights but again started to feel something is wrong with the car. The problem is not bad (or maybe not even noticeable for someone does not know the story), but i feel hesitation under load at low speeds and fuel consumption is getting higher (not as obvious as the first time).

I have a cheap OBD reader, and after a 25mins drive in the city, it shows 0 misfire for Cylinder 1, 1 misfire for Cylinder 2, 2 misfires for Cylinder 3 and 4 misfires for cylinder 4. I had the dealer check it via original Mazda software, they also did a test drive, but told that everything is fine. Would be great if you guys have any idea of what is wrong (or is it my obsession), thanks in advance.

I have uploaded a video with misfire and live data readings:

https://www.youtube.com/watch?v=VgL7OlvO-Hg
 
Last edited:
What was the CEL code before you took it to the dealer?

Your current scan tool live data at idle looks spot on. Those few misfires were just idling, or was there some driving on this running cycle?

I'd do a couple of in-drive deep throttle blips (brakes applied) and then look at misfire counts, to see if it is acts up under load.
 
Sounds like the coil packs/boots may be going bad. You might wanna swap one of the boots that belong to cylinder one (which is not throwing a code to one of those that is experiencing the problem) and see if the problem follows the boot or remains in the same cylinder.

Alternatively, could be that the gaps on the spark plugs are too large and causing misfires. But I would first try what I advised in my first paragraph before I go in this route.
 
What was the CEL code before you took it to the dealer?

Your current scan tool live data at idle looks spot on. Those few misfires were just idling, or was there some driving on this running cycle?

I'd do a couple of in-drive deep throttle blips (brakes applied) and then look at misfire counts, to see if it is acts up under load.

It was Cylinder 2 Misfire, dealer changed the coils' order but it was still cylinder 2, so they have changed the spark plugs and the code did not come back. It has been 3k miles with the new spark plugs and I still do not have a code.

I have also tried to rev it up with brakes, misfire counts did not go up, then I took a 25mins drive and shared the results in the first post. I have visited the dealer last week, they checked with their software and said that everything is fine, advised me to stop thinking about it :) They have cleaned the throttle body btw, which was really dirty, and had the injectors cleaned, but I do not feel a difference in the way it drives, but the mileage seems to be improved ~5%, idk if it is possible.

Sounds like the coil packs/boots may be going bad. You might wanna swap one of the boots that belong to cylinder one (which is not throwing a code to one of those that is experiencing the problem) and see if the problem follows the boot or remains in the same cylinder.

Alternatively, could be that the gaps on the spark plugs are too large and causing misfires. But I would first try what I advised in my first paragraph before I go in this route.

They have used oem spark plugs, I am known as an obsessed customer so we have checked the gaps before installing and torqued (which is considered as rocket science here in Turkey).

Misfire counts are very low and sometimes it is 1-2 for all cylinders. I do not have a cylinder that has 0 misfires all the time (according to the obd reader I have). I have ordered new coil packs, which is really expensive and hard to find (I guess we have more Bugatti Veyron's than CX-5 here), hope they will arrive in 3 weeks. Dealer said this is really unnecessary without a code or more visible indications, but I cannot stop myself.

The only finding that makes sense was the condition of the engine mounts. There was another CX-5 in the dealer, same year and model with way less mileage, the engine vibration was very similar but it did not transmit it to the chassis like mine did. Dealer said there is wear on the mounts but it does not need a immediate change, it is barely noticeable while idling or driving. But again I have ordered (again 3 weeks) and waiting for them to arrive.

So I am in a rare situation where dealer wants me to go away and drive my car, but I insist on visiting them and throwing parts on my car.
 
Back