Misfire or CVT failure imminent?

[Ilya]

For those of you who have experienced CVT failure - what were the symptoms?

2016 QX60. Just under 125kmi.

Trans/Front Diff/Rear Diff fluids were changed by Infiniti at 75kmi and 105kmi (we purchased the car at 22kmi).

A week and a half ago, wife got a P0302 (Cylinder 2 Misfire). I cleared the code and it hasn't come back. However, pretty regularly now around 1,900-3,000 RPM, the car will jerk as if it's misfiring but no code (pending or otherwise). I've put the car into manual mode and this has happened in 2nd through 7th gear. Spark plugs were changed at 100kmi. I purchased 2 new coil packs and will replace the #2 one when I get them.

Is this sounding like the CVT is about to give up the ghost? Please tell me it ain't so - I was hoping to get 3 or so more years out of this vehicle before replacing it.

[VStar650CL]

Nope, that sounds like an engine hiccup. The symptoms of a slippy belt usually show up first with light pedal up a hill, as repetitive jumping both palpably and in the tacho. Nissan calls that "judder". Single hiccups won't cause a P030x, the miss needs to happen a good number of times consecutively before the ECM will flag it. On the other hand, any little slip will usually cause the TCM to throw a P17F1 judder code. So with a prior P0302, no P17Fx, and symptoms which don't really jive with judder, I'd say it's safe to assume the CVT is not the issue.

[Ilya]

Nope, that sounds like an engine hiccup. The symptoms of a slippy belt usually show up first with light pedal up a hill, as repetitive jumping both palpably and in the tacho. Nissan calls that "judder". Single hiccups won't cause a P030x, the miss needs to happen a good number of times consecutively before the ECM will flag it. On the other hand, any little slip will usually cause the TCM to throw a P17F1 judder code. So with a prior P0302, no P17Fx, and symptoms which don't really jive with judder, I'd say it's safe to assume the CVT is not the issue.

Phew! Will the P17Fx code appear on an OBD scan or do I need a tool that can scan the TCM?

[VStar650CL]

Because it's a "P" code, most regular scanners will pick it up. There's always CVTz50 if you want to be certain. The tran-ny is a '10E, same as most of the R52 Pathfinders, so CVTz50 will definitely talk to it.

[Ilya]

Because it's a "P" code, most regular scanners will pick it up. There's always CVTz50 if you want to be certain. The tran-ny is a '10E, same as most of the R52 Pathfinders, so CVTz50 will definitely talk to it.

This is awesome - thank you!

I should be getting the new coil pack(s) sometime this week - for now my wife has a bunch of errands to run, is it safe to continue driving the car even when it's herky jerky? I told her to take it easy and not try to power through the jerks but let off the throttle and try again since it only happens like 75% of the time right now.

EDIT: Bought the app, this is amazing! Seems like based on these screenshots my CVT is doing just fine? It detected no codes (forgot to screenshot that).

[VStar650CL]

Yep, she looks pretty happy. Pump is healthy, pressures are normal. You have the same 140F radiating cooler as an R52 Pathy, which is a really nice setup in your much-warmer climate. Keep an occasional eye on the temperature and get used to where she runs, that way if anybody screws up a maintenance change you'll know within a few miles because she'll get hot.

Incidentally, check out the engine work support. You can now DIY your IAVL's and a bunch of other stuff. Very handy.

As far as the misfire, it's probably heating up the front cat a little bit, but as long as it doesn't degenerate into a "dead" miss and you don't have any heavy smell from the tailpipe, gentle driving should be okay.

[Ilya]

Yep, she looks pretty happy. Pump is healthy, pressures are normal. You have the same 140F radiating cooler as an R52 Pathy, which is a really nice setup in your much-warmer climate. Keep an occasional eye on the temperature and get used to where she runs, that way if anybody screws up a maintenance change you'll know within a few miles because she'll get hot.

Incidentally, check out the engine work support. You can now DIY your IAVL's and a bunch of other stuff. Very handy.

As far as the misfire, it's probably heating up the front cat a little bit, but as long as it doesn't degenerate into a "dead" miss and you don't have any heavy smell from the tailpipe, gentle driving should be okay.

Thank you for all of the information...this tool will be incredibly handy indeed! Never even crossed my mind to search the app store for a way to scan the CVT hah.

[VStar650CL]

You're most welcome. It's my secret weapon, I keep a dongle in my pocket and use it a lot for quick scans in the service drive. Beats the crap out of the snail-slow Consult3+. I dearly wish they'd make it work with the most recent CVT's and TCM's. I keep hopin' but that ain't happenin'.

[Ilya]

Replaced the coil pack today and drive into town was beautiful. On the way home, for about 10 seconds of a 25 minute ride, I had some more jerking...but no CEL again (CEL was on before I changed the coil pack - came back a 2nd time eventually). But then it was fine the remainder of the ride home for nearly 20 min.

Guess I'll keep an eye on and if it continues, maybe swap out the spark plug that only has 25kmi on it.

[VStar650CL]

You might have more than one coil going south. Like I mentioned earlier, you need a pretty good number of consecutive misses before a Nissan ECM will throw a misfire code. Might just be old age, or you might have resistance in your engine ground making the coils overheat. If voltage drop shows up okay, you might just want to assume agetism and replace the other five.

[Ilya]

You might have more than one coil going south. Like I mentioned earlier, you need a pretty good number of consecutive misses before a Nissan ECM will throw a misfire code. Might just be old age, or you might have resistance in your engine ground making the coils overheat. If voltage drop shows up okay, you might just want to assume agetism and replace the other five.

I did order 2, so I have another new one ready to go once I get a code if it's no longer #2...but yeah, at 125kmi, it's probably time. A lot of stuff is starting to go hah - hood struts, coil pack(s), so many rattles in the interior that I drown out with music...after 9 years I suppose it's expected lol.

That does remind me...probably wouldn't hurt to remove some grounds and clean them up next time I'm working on the car. It's always a hunt for them though - any obvious ones you suggest?

(should clean the grounds on my M56x too for good measure)

EDIT: P0302 came back on. Wife was driving today and it lit the CEL. So either spark plug is failing after 25kmi or...I got a bad coil pack or...when I remove the spark plug I'm going to find oil or something? Ugh...

[VStar650CL]

Could be an injector too at 125K. Is there a difference between the banks in STFT?

One other thought, how hard does the car get driven? VQ's are kind of infamous for carbon buildup on the crowns when they're driven like grandma.

The ECM and virtually everything else on the engine grounds through E9 and E15. They're on the fender support underneath the airbox. I know the '16 FSM here in Nico is f#cked, but that stuff will be identical on a '15. See page PG-46 here:
https://www.nicoclub.com/service-manual ... 5%2Fpg.pdf

[Ilya]

Could be an injector too at 125K. Is there a difference between the banks in STFT?

One other thought, how hard does the car get driven? VQ's are kind of infamous for carbon buildup on the crowns when they're driven like grandma.

The ECM and virtually everything else on the engine grounds through E9 and E15. They're on the fender support underneath the airbox. I know the '16 FSM here in Nico is f#cked, but that stuff will be identical on a '15. See page PG-46 here:
https://www.nicoclub.com/service-manual ... 5%2Fpg.pdf

I can take a look at the STFT - good idea to see how the injectors are operating. Will post in the next day or two.

The car is driven decently, I wouldn't say I beat on it like my M56x but it gets WOT more than a few times a month (1-2 a week) due to living in the country and often having to pass slow traffic like tractors on two lane roads.

Thank you for the FSM page and reference.

[Ilya]

At idle:



At 2,500rpm (stationary, in park):

[VStar650CL]

There's no real imbalance in the STFT or LTFT, that pretty much leaves out an issue with a single injector. When an injector sticks it will generally show up as the ECM adjusting the bank rich, if one leaks it shows up as an adjustment lean. Yours are pretty balanced. Since both are in the normal range, that pretty much limits it to something very intermittent, which points to ignition or timing. If coils don't do it, the next likely suspects are CMP's or CKP.

[Ilya]

There's no real imbalance in the STFT or LTFT, that pretty much leaves out an issue with a single injector. When an injector sticks it will generally show up as the ECM adjusting the bank rich, if one leaks it shows up as an adjustment lean. Yours are pretty balanced. Since both are in the normal range, that pretty much limits it to something very intermittent, which points to ignition or timing. If coils don't do it, the next likely suspects are CMP's or CKP.

Yeah I did see some slight variation on the STFT of like 1.56 to 2.34 and sometimes bank 1 was the first value while bank 2 was the second...might have hit 3.0 at one point but still within a point of each other.

If I remember correctly from my 4th Maxima days - the CMP and CKP can just be cleaned from the dirty and 'sludge' on the end? I remember they are pretty cheap so maybe throwing new ones on there even for preventive maintenance wouldn't be the worst idea?

[VStar650CL]

Cleaning them may help, but they're not so cheap anymore, at least not for OEM ones. But I strongly discommend aftermarket Hall sensors on Nissans. The amount of head-scratching and hair-pulling I've seen over the years just ain't worth it.

[Ilya]

Cleaning them may help, but they're not so cheap anymore, at least not for OEM ones. But I strongly discommend aftermarket Hall sensors on Nissans. The amount of head-scratching and hair-pulling I've seen over the years just ain't worth it.

Other than Oxygen sensors (I prefer Bosch plug'n'play), I've learned a long time ago that it's best to just pay for OEM and be done with it. I just spent $60 on Washer Fluid Pumps for this QX60 over the past 3 years from Amazon which only lasted like 1-1.5yrs max and had much lower 'pressure'. Finally broke down and got the whole washer fluid tank and pump combo (Infiniti doesn't sell just the pump which is so dumb) and not only is the spray quality/pressure better, but it should last many years.

[Ilya]

The code came back as did the misfiring so decided to swap that one plug. Very very faint bit of moisture when I wiped the plug on my glove, but it did smell like oil. Possible valve cover gasket issue? How difficult is that on this car? I don't think I've ever done a valve cover gasket replacement before on any vehicle - been lucky.

[VStar650CL]

That's some pretty gnarly carbon on the piston crown, and it looks like it's breaking loose and causing adhesions on the spark plug. I'd decarbon that engine before doing anything else.

[Ilya]

That's some pretty gnarly carbon on the piston crown, and it looks like it's breaking loose and causing adhesions on the spark plug. I'd decarbon that engine before doing anything else.


Carbon Adhesions.png

Any recommendations on best product for that? I do put Seafoam through the gas tank every 10-12 or so fillups.

[VStar650CL]

Whatever you're doing isn't enough lol. That's some gnarly s#it.

I decarbon at the shop by putting a capful of ATF (any kind) into any handy vacuum orifice (usually the brake booster) while an assistant holds the (fully warm) engine at about 4K RPM. Carbon is hard but brittle, the cold mineral oil vapor coats it and the temperature differential between the surface and substrate causes it crack off the metal like popcorn.

[Ilya]

Whatever you're doing isn't enough lol. That's some gnarly s#it.

I decarbon at the shop by putting a capful of ATF (any kind) into any handy vacuum orifice (usually the brake booster) while an assistant holds the (fully warm) engine at about 4K RPM. Carbon is hard but brittle, the cold mineral oil vapor coats it and the temperature differential between the surface and substrate causes it crack off the metal like popcorn.

Okay, so same process as Seafoaming a car through the intake (as opposed to gas tank). I'll have to do this - it's actually been a while hahah. I did it on my M56x regularly but even that one is due.

[Ilya]

VStar, are either of these lines good for ATF/Seafoam? Left one perhaps?

[VStar650CL]

Yep, that's the booster vacuum, it will work fine. Just keep it plugged until your assistant raises the RPM, because it will create a vacuum leak large enough to stall the engine at idle speed. I usually stick a bolt in the hose while the engine warms up, then pull the plug when it's ready for the ATF.

[Ilya]

Yep, that's the booster vacuum, it will work fine. Just keep it plugged until your assistant raises the RPM, because it will create a vacuum leak large enough to stall the engine at idle speed. I usually stick a bolt in the hose while the engine warms up, then pull the plug when it's ready for the ATF.

Thanks! I like the bolt idea. Will use the left hose.

[VStar650CL]

[Ilya]

Car smoked like a mother after the Seafoam treatment - so far so good, with a new coil pack, new sparkplug and seafoam she seems to be running amazing.

[VStar650CL]

Mineral oil doesn't make a cloud like that, it's one of the reasons I prefer it. But SeaFoam does do a fine job, cloud notwithstanding. Glad to hear she's running better!

[Ilya]

I felt really bad when I did it because I had to drive by a guy on a tractor as I was giving the car the beans...poor dude probably couldn't breath for a good 5 minutes afterwards. Hope he was okay lol.