Z '23 Engine "Misfire"? Intermittent Exhaust Popping at Idle

[qellman32]

Hey, long time no see.

I think my 2023 VR30 is having a weird issue.
41,000 miles

Several days ago, I was driving normal road speeds around town, driving for GrubHub. So like in-town 35 MPH. Something on the dash caught my eye. I looked down to see (I thought) the Check Engine light flashing for about 5-10 seconds, then extinguish. "Huh, that's mildly alarming." It was running so well previously, and technically afterwards. So, I watched it like a friggin' hawk.

Of course, it was getting dark, so I had to figure this out fast. I'm like 45 minutes from my house.

So I stopped at the next order's restaurant and listened. The idle was around 1100 RPM, which is higher than normal, and every now and then there was a...a shimmy. Like a little dropout.

------.------.---.------.-------.---.----
I'm like "huh, that's never happened before". Turning off to pickup the food, then turning it back on didn't really fix it. When I took off, the engine light never returned and the engine was smooth when accelerating, but it moved quickly through the gears, like it was in a hurry to get to 9th gear (quicker than normal). It would run at 40-45MPH at 1200-1500RPM in 9th gear, usually it holds gears to keep the RPM a little higher for economy (above 2000)

When I looked into it, the manual says "potential emission control malfunction" and "Malfunction Indicator Light blinking" is "an engine misfire has been detected"?!?!

I had a 20-mile drive before a 40 mile drive back home . It handled it well, at 29MPG. I WAS CONFUSED. The next day, same thing. Drove around for 5 hours, same behavior. If I drove it harder than a grandma, it smoothed out and drove like a champ (showing off and all). Slow down, back to shifting in a hurry.

So I'm thinking that my injectors are clogged. I had used Sam's Club premium gas a second time after I said I wouldn't, but it was cheap. First time, it worked similarly, then I put in Shell V-Power and it worked like magic. It was a bit too expensive, so I had to do Meijer Premium (it was $1 off/gal with points). This time I added Iso-HEET to the 12 gallons in the tank. On the drive home, it drove same as previous.

After I parked up, as soon as I put in Park, the RPM's raised to 1100 RPM, but sounded very different from normal (hopefully you guys can see the video I made). It also smelled a little different from the exhaust (I figured that was the Iso-HEET "working"). I flipped to the "Sport" dash display and, after sitting for a little while, the water temperature rose somewhat slowly to 213F before I shut it off.

I don't know what to do. Google says Iso-HEET is safe for pretty much all circumstances. I'm scared to start it back up. I scanned it with Torque Lite on Android and a Bluetooth OBDII Adapter. No codes. I saw when the dropouts happen before Iso-HEET, the Timing Advance jumps from 3 degrees to 5 degrees and back at idle. And the Fuel Trim seems to average lean (I think, it's hard to figure with a turbo engine).

What do you guys think?

 

[FSUZ33]

To Start, I don’t know what’s causing this. These are suggestions.

Check that the gas cap it tight.
These cars are really sensitive to bad gas. And from what I’ve read, octane and fuel additives too. How full is your tank? I’d try to get as much good gas in there as possible, no additives.
Disconnect the battery (30? minutes) to try and reset everything.
Keep an eye on your gauges.
Most cars have to misfire a certain number of times to throw a DTC. So its good you didn’t have a DTC, but doesn’t mean it’s not misfiring.

Personally, I’d tinker with mine a little first, but thinking it would be a good idea take it straight in for service to avoid something catastrophic.

 

[KrackaC8]

If it truly was a misfire, I'd say spark plugs is the easy answer, but that doesn't seem to be the issue here.

You likely need to stop with the crap gas and stick to the TopTier premium brands. HEET is just alcohol meant for water contamination (a gallon of E85 is a cheaper & easier way to accomplish the same thing).

Dump in a bottle of Chevron Techron complete fuel system cleaner and get some proper fuel in there. If the issue persists, get it into the dealership since you're still under your factory 5/60 powertrain warranty.

 

[qellman32]

Update:

I had the idea of cleaning my Throttle Bodies from doing the same thing in my previous 2016 Jeep Cherokee. Then, it ran a little smoother and took off & cruised easier. So, why not. It wasn't easy to do on the Z, but I struggled through.

I was rewarded with no trans shift issues, and smoother dropouts (they're still there, but like rounded over). I also relearned my throttle position. Thing feels almost factory new.

Now I MUST tackle somehow the Fuel Starvation problem. It's really ANNOYING!

P.S. not sure if this matters, but I also put the front undershoud back on, just in case that was causing some issues.

 

[Zplz]

Why not just take it in to a Nissan dealer, especially under warranty? Why monkey around with a major investment?

 

[qellman32]

Why not just take it in to a Nissan dealer, especially under warranty? Why monkey around with a major investment?

No Check Engine light, no codes to show. Plus I'm only doing basic maintenance, nothing big. I don't touch the major stuff, till after the warranty is up.

 

[mikecarpage]

based on the video, the issue doesn't sound too good. it could be a number of things that throw off an idle (oxygen sensor, fuel system parts, ecu, etc.) I had an issue similar to this on another car where the engine was shaking and idle was rough.

I would think the dealership can trace back the flashing check engine codes to see what it was. With the symptoms in the video, I'd have it checked out just to be safe.

(ps I was hopeful that you'd have many more miles by now)

 

[qellman32]

based on the video, the issue doesn't sound too good. it could be a number of things that throw off an idle (oxygen sensor, fuel system parts, ecu, etc.) I had an issue similar to this on another car where the engine was shaking and idle was rough.

I would think the dealership can trace back the flashing check engine codes to see what it was. With the symptoms in the video, I'd have it checked out just to be safe.

(ps I was hopeful that you'd have many more miles by now)

I think I will have the dealership look at it anyway. It's a little unnerving.

(That's a long story involving the price of insurance in Michigan and the state wanting me to pay 6-months up front lol)

 

[qellman32]

Update #2

It finally had a solid engine light. A P0306 code, indicating a Misfire on Cylinder 6.

I was honestly relieved when I saw it. I set up a dealer appointment immediately. It was 3 weeks out. Apparently, all of the loaners were taken and they were backed up with other repairs (is it a sign?).

I finally got my loaner car, a 2024 Sentra.

Not bad. It drive really nicely, but I'd be concerned with the CVT.

Anyway, after a few days, the service guy called me and said it was the Cylinder 6 Spark Plug. I'll admit, you guys were right.
But the quote was $900 . It's a 'wear item', of course, so no Powertrain Warranty.

He said he did a coil swap, but the problem persisted. Then "we ordered and replaced #6's plug and the problem went away. But we would want to replace all of the plugs because they wear the same". He threw in an Injector Cleaning too. Needless to say, I declined.

So, I set about doing the plugs myself.

It was actually very easy, once you get passed the intercoolers, and the brace bar, and the stupid zip ties, and the wires deliberately placed tightly over the coils...‍. But it got done. And I was rewarded! It's got its MOJO back! Zero problems. I'll be sure to drive it harder for the injectors lol.

 

[qellman32]

I forgot to include the service sheet.

 

[FSUZ33]

Had a coil go out on my last 350 so I replaced all 6 coils and plugs. It was a pain as everything's tied up and underneath levels of other stuff. I think I had to remove both upper and lower intake plenum, can't remember. I guess with this one, add intercoolers/piping to the mix.

Great work!

 

[bpeckham]

Thanks for the excellent write-up @qellman32, now that the original '23s are falling out of warranty (or simply running through wear items), it's good to see what we might expect down the road.