Ignition gremlin

[50jeffrey]

2015 CX-5 2.5L

Over the past 6 months the CEL has come on multiple times and the code is always P0301 - Cylinder No. 1 misfire. No detected driveability issues

After the first time, I just went ahead and replaced the no. 1 ignition coil ( the plugs were all replaced just over 20,000 miles prior - NGK Iridium long life). Cleared the code and for the next month or so, all was good.

CEL came on again, so I replaced the plug for the no. 1 cylinder and swapped the no. 1 and no. 4 coils. Cleared the code and all was good for about another month.

CEL came on again, so I installed another new coil for the no. 1 cylinder. Cleared the code again and all was for good for another few weeks.

CEL came on again. Did nothing this time and after two weeks the code cleared by itself.

CEL came on again for a few days and then cleared.

CEL came on again for another few days and then cleared again.


I am at my wits end as to what is going on. Any ideas?

 

[markjenn]

There are things other than ignition which can cause a misfire code trip... clogged fuel injector, mass airflow sensor issues, even low compression. If you want to throw parts at it, I’d do injector next, perhaps just a troubleshooting swap with another cylinder.

- Mark

 

[yrwei52]

2015 CX-5 2.5L

Over the past 6 months the CEL has come on multiple times and the code is always P0301 - Cylinder No. 1 misfire. No detected driveability issues

After the first time, I just went ahead and replaced the no. 1 ignition coil ( the plugs were all replaced just over 20,000 miles prior - NGK Iridium long life). Cleared the code and for the next month or so, all was good.

CEL came on again, so I replaced the plug for the no. 1 cylinder and swapped the no. 1 and no. 4 coils. Cleared the code and all was good for about another month.

CEL came on again, so I installed another new coil for the no. 1 cylinder. Cleared the code again and all was for good for another few weeks.

CEL came on again. Did nothing this time and after two weeks the code cleared by itself.

CEL came on again for a few days and then cleared.

CEL came on again for another few days and then cleared again.


I am at my wits end as to what is going on. Any ideas?

I assume the CEL you’re getting has always been P0301 - Cylinder No. 1 misfire. Are the “NGK Iridium long life” spark plugs you’re using the Laser Iridium spark plug ILKAR7L11 / 94124? And are you using the OEM ignition coil or aftermarket part?

At this point I’d start to check something else like markjenn suggested. Do the easier ones first such as checking the cylinder compression. Check all the wirings to the cylinder #1 ignition coil. If you’re using NGK ILKAR7L11 / 94124 plugs, try a set of OEM PE5R-18-110 plugs instead, not just one. If you use aftermarket ignition coil, try the OEM coil too. Swapping the fuel injectors would be the next if everything mentioned above failed.

 

[50jeffrey]

I assume the CEL you’re getting has always been P0301 - Cylinder No. 1 misfire. Are the “NGK Iridium long life” spark plugs you’re using the Laser Iridium spark plug ILKAR7L11 / 94124? And are you using the OEM ignition coil or aftermarket part?

At this point I’d start to check something else like markjenn suggested. Do the easier ones first such as checking the cylinder compression. Check all the wirings to the cylinder #1 ignition coil. If you’re using NGK ILKAR7L11 / 94124 plugs, try a set of OEM PE5R-18-110 plugs instead, not just one. If you use aftermarket ignition coil, try the OEM coil too. Swapping the fuel injectors would be the next if everything mentioned above failed.

I used the NGK part number that you cited. That is number that is actually stamped on the factory plugs. A did use a Mazda coil, both times.

 

[edmaz]

Not wanting to sound like the fly in the ointment here, but IMO working with the injectors on our vehicles does not appear to be nearly as fast and easy as on most of the older port injected engines.

Although I naturally haven't done this myself, according to the FSM, the job comes with extra baggage, such as removing the intake manifold; and there is an SST (49 D013 104) specified for installation of the multiple injector seals. Don't know if doing the work without the Mazda special tool is feasible, but I'd want to have it sourced just in case. And a new set of injector seals is listed as required as well for every injector replacement.

So what I'm getting at is that replacing or swapping injectors is not something that I'd be doing on a 'give-it-a-shot' basis. Sure, if one was diagnosed as most likely defective, then all of the associated work becomes required, but not until then (on my vehicle anyway).

What I would most definitely do is to try a bottle of Techron Complete Fuel System Cleaner. Never a bad thing to do, and may clean out a slightly gunked-up injector.

The other interesting thing about the OP's issue is the lack of any noticeable performance problem, and also that the code gets cleared by the ECM. This suggests that the misfire is a very infrequent condition, which goes away immediately after the code is set. So all of this would make me want to know what the OBD misfire counters look like, particularly after the misfire code is set. Of particular interest is the misfire count of cylinder #1, compared to the other 3 cylinder misfire counts.

 

[yrwei52]

I used the NGK part number that you cited. That is number that is actually stamped on the factory plugs. A did use a Mazda coil, both times.

Yeah I understand the NGK ILKAR7L11 / 94124 plug is supposed to be equivalent to OEM plug, but there’re reports that by using OEM spark plugs which eliminated the mis-fire CEL. That’s a “cheap” try comparing to swapping the fuel injectors. And try a couple of good fuel injector cleaners suggested by edmaz is a good idea too. Low cylinder #1 compression could trigger the mis-fire as reported by others.

 

[50jeffrey]

Changed the original plugs out at 75,000 miles as recommended by the manufacturer. Problem did not begin to occur until the car had approximately 90,000 miles. And still had the CEL nearly immediately after replacing the one for the no. 1 cylinder when the problem began. And, while not mentioned initially, did add a bottle of PEA cleaner to the gas tank and also used an intake cleaner, as well.

 

[yrwei52]

Changed the original plugs out at 75,000 miles as recommended by the manufacturer. Problem did not begin to occur until the car had approximately 90,000 miles. And still had the CEL nearly immediately after replacing the one for the no. 1 cylinder when the problem began. And, while not mentioned initially, did add a bottle of PEA cleaner to the gas tank and also used an intake cleaner, as well.

Read this thread about mis-firing CEL. The OP FrozenApple and a couple of others had their engine replaced due to low compression on the particular cylinder which triggered mis-firing CEL.

2019 CX-5 2.5T Misfire

 

[markjenn]

It does sound like injector swapping/replacement is not an easy fix. I’d check compression next and monitor fuel mileage. Vacuum leaks are another strong possibility. I bet #1 is running just on the ragged edge of being too lean. Does the plug look different than other 3?

If the car is running okay, might be something you just live with and monitor for awhile to see if problem goes away or becomes worse. The easiest way to fix a CEL is with a bit of strategically placed black electrical tape!

I wonder how misfires are detected on individual cylinders? Could this be a sensor issue? If the #1plug looks the same, engine has no detectable misfire stumble with good uniform compression, and fuel mileage is unchanged, I start to wonder if this is an instrumentation issue rather than an actual fault.

- Mark

 

[edmaz]

… If the car is running okay, might be something you just live with and monitor for awhile to see if problem goes away or becomes worse. ….

That would be a possibility, unless the OP lives in a state that does emission testing, where a CEL will mean rejection. It wasn't mentioned, so I'm guessing that's not a factor on this one.

….
I wonder how misfires are detected on individual cylinders? Could this be a sensor issue? If the #1plug looks the same, engine has no detectable misfire stumble with good uniform compression, and fuel mileage is unchanged, I start to wonder if this is an instrumentation issue rather than an actual fault.
...

The ECM continuously computes precisely how much engine rotation should take place from each cylinder detonation, and it checks that expected computation against actual (crank, …) sensor input. Any time the actual result doesn't match the expected, a misfire is recorded for that cylinder. If some predetermined number of misfires takes place over a specified amount of time, one or more pending or actual misfire codes are set.

So this makes it fairly unlikely that a misfire code is ever going to be bogus. However, any weird outcome is possible when electricity is involved, so it can't be ruled out either. That's why I mentioned checking the OBD misfire counters, in order to see if those numbers have at least some correlation to these sporadic cylinder #1 misfire codes that are being set (and cleared).

And I agree with everyone who recommended a compression test. A simple and easy test that can provide very helpful information.

 

[CharlestonMX5]

Do you ever have any pending codes ?

 

[minnesotaart]

I'd keep it even simpler than some of the others here. As noted, check that all of the electrical connectors are snug at the coils, at the ECU and at the battery. I'd also disconnect the battery for a while and see if the code appears again after reconnecting the battery resets everything. This is all free!

 

[FrozenApple]

Before throwing parts at it... maybe do some simple diag first.

Try swapping the coils with cyl #2 see if the misfire stays at #1 if misfire moves to cyl#2 you know its the coil. If not swap the spark plugs and recheck datalist.

Look at datalist to see the misfire monitor, see which cyl is currently misfiring.

One last thing to check for is freeze frame, when did the misfire code set? is it when the car is cold or hot idling? or driving?

Simple steps to pin point exact problem, no point of guessing

 

[50jeffrey]

Before throwing parts at it... maybe do some simple diag first.

Try swapping the coils with cyl #2 see if the misfire stays at #1 if misfire moves to cyl#2 you know its the coil. If not swap the spark plugs and recheck datalist.

Look at datalist to see the misfire monitor, see which cyl is currently misfiring.

One last thing to check for is freeze frame, when did the misfire code set? is it when the car is cold or hot idling? or driving?

Simple steps to pin point exact problem, no point of guessing

Did all of that (moving parts around and replacing parts). I described it in my original posting

 

[FrozenApple]

Did all of that (moving parts around and replacing parts). I described it in my original posting

what about freeze frame? when did dtc set?

 

[50jeffrey]

Don't have a scanner capable of getting that info.

 

[FrozenApple]

Don't have a scanner capable of getting that info.

ok well.. base on this.. since you have no access to a more comprehensive scan tool, im going to assume this issue comes and goes.

1. It is most likely not a fuel injector issue
2. The plugs is most likely fine since u already replaced and swappd coils and plugs.

Try something for me, clear the code and everytime before you drive, idle the vehicle for 3-5 min and see if check engine light returns quicker, comparing to the current interval(1 week)

 

[AVC]

I think you better rule out or confirm low compression for cyl #1...

 

[edmaz]

Every reply so far from the OP has been that he already tried what's been suggested, or doesn't have the diagnostic tool. And no response at all from him about the compression test suggested by multiple people here. Could be he's waiting for someone to tell him exactly what the problem is, which of course is never going to happen without additional diagnosis. Seems like we're riding on the train to nowhere.

 

[50jeffrey]

ok well.. base on this.. since you have no access to a more comprehensive scan tool, im going to assume this issue comes and goes.

1. It is most likely not a fuel injector issue
2. The plugs is most likely fine since u already replaced and swappd coils and plugs.

Try something for me, clear the code and everytime before you drive, idle the vehicle for 3-5 min and see if check engine light returns quicker, comparing to the current interva

Every reply so far from the OP has been that he already tried what's been suggested, or doesn't have the diagnostic tool. And no response at all from him about the compression test suggested by multiple people here. Could be he's waiting for someone to tell him exactly what the problem is, which of course is never going to happen without additional diagnosis. Seems like we're riding on the train to nowhere.

The problem is that it is my daughter's car and don't get to have access to it all that often. I have to make a special trip to meet her half way between where she lives and where I live, to swap cars and bring it back to my house. Occasionally, she stops down for an overnight stay. A neighbor has a pressure gauge that I can borrow and use next time I have access to the car.