Change 1 or all Ignition Coils on my M45

[ts385]

Hello,

I recently had a check engine light in my M45 and after I took to autozone it showed that there was an issue with my #4 injector. The guy at autozone and the web said this is most commonly due to a faulty ignition coil, and I was wondering if it would be worth it to replace all or just the faulty one?

I have a 2003 Infiniti m45 with 210k miles, looking to keep it for at least another 100k.

Thank you in advance for feedback.

[EdBwoy]

Might you have that code that autozone got?

I wouldn't go spending money on 8 coils yet. My suggestion would be to move that coil pack to cylinder #2, and if the trouble code points to a misfire on #2, then the coil is your true culprit.
If the code stays at #4, then it could be your spark plug (depending on when they were last replaced) or less commonly an injector issue.

[ts385]

The code is p0304, #4 cylinder misfire detected.

I just don't want to worry about changing another one in another few months.

[EdBwoy]

In that case, I still recommend moving that coil pack to cylinder X and see if you now get code p030X. My experience tells me it's more likely to be a spark plug than coil pack.
If you want to do a long term fix, then replace all 8 plugs while at it. If the problem is indeed the coilpack, I'd replace just that one.
Others might offer a different opinion, good luck mate

[paranoidjack]

I'm surprised to hear that, since coming from an '00 Q45 the coil packs were HUGELY problematic...so the VH45's don't have this issue? Good to hear but hard to believe.

[EdBwoy]

I'm surprised to hear that, since coming from an '00 Q45 the coil packs were HUGELY problematic...so the VH45's don't have this issue? Good to hear but hard to believe.

Hold on now, don't go blowing your coilpack savings quite yet if you've always had bad luck with coilpacks. [This will be long, but here is how I justify my recommendation]

Electronic/ electric components can be interesting. If you have a manufacturing defect your new coilpack will either not work, or just die shortly after installation. If you mishandle it such as drop it from an unreasonable height, one of those 2 situations might happen. Again, if the manufacturing specs are off, one of those might happen (this is why I go for OEM only on some of my replacements). On the other hand, some electronic components pretty much outlive the car, for example the Engine Management computers.
... then there's the classic abrupt and random failure; which the OP's could be.

I had a 2001 q45 for a pretty short time but at 256,000 miles I think the coilpacks had only been replaced once, assuming with the updated ones, if that had been a problem. Same thing happened to the 2000+ maximas with their goofy coilpacks but updated versions with grey dots were way more reliable - manufacturing standards changed??
The spark plugs though, those are wear items. You keep shooting electricity through metal and give it numerous explosions and at some point it will wear out. In my mind, if one cylinder has a spark plug worn enough that the gap was off enough to throw a code, the other ones might not be too far behind. I suppose you could just regap and continue. Of course this is assuming all other components are operating like they should.

This is all just one guy's experience and your results may vary. Plus, I haven't really heard of many complaints from VK45 owners about coilpacks.

[ts385]

I appreciate all the feedback.

I had the spark plugs changed about 20k miles ago, and the M45 ran very smooth afterwards so I doubt they did not gap the spark plugs properly. Also, when my check engine light originally came on a couple weeks ago, I started driving more conservatively (only drive her a couple times a week these days), and the light went off. Over the weekend I pushed her over 4000 RPM a couple times and the light went back on, so it leaves me to believe that there is something failing.

My whole purpose in reaching out to the forum is to avoid going to the dealership at all costs, it was a fiasco the last time I went.

So if I changed the ignition coil and spark plug on #4 would it be safe to say the issue will be fixed for sure?

[EdBwoy]

I would say most likely, but I don't want to definitely say so. 20K miles ago someone could have gapped the plugs wrong or used the wrong brand.
You have to do a little bit of troubleshooting and moving that coil pack is the cheapest and simplest you can do. A 10mm socket and ratchet will do

[Double E]

Agree on this. Do the switch to another cylinder to see if the code moves with the coil. If not, don't toss money at a good coil.
Agree that some Nissan coils were problematic. The VQ engines went through a "spell" with bad ones as described above. I also experienced the good & bad years with the VQ engines.

The Y34 is not prone to bad coils however. Not saying it is not possible, but I would start with simple & easy stuff to do first. My first Y34 went to 140K miles on original coils before the accident.