Altima Misfires

Hi All,
My 2008 Nissan Altima 2.5S started logging misfires. They're about 85% on cylinder 1, 10% on cylinder 2, 5% on cylinder 3 and none on cylinder 4. Eventually the CEL comes on with P0301 and one time with P0300. I cleared codes once and ran at idle and no misfires were recorded. I switched coils 1 and 3 but misfire pattern didn't change. I changed old Autolite plugs for new NGK plugs but misfire pattern didn't change. Mechanic says it needs a new engine because timing chain is making noise. I understand that a loose timing chain can cause misfires but I've seen videos where the timing chain noise is really noticeable whereas mine is barely noticeable.
Anyway, I was wondering if the following charts of live data show an obvious issue. Is it obviously a timing issue or does it scream fuel delivery issue or something else. Thanks

sorry for the duplication

Your captures seem to indicate good fuel control, but it's hard to say if there's a timing problem or not. We'd need to see the VVT PIDs for that.

Did you happen to check your Freeze Frame when P0301 or P0300 sets? If not, wait for the code(s) to set again, and see what the Freeze Frame has to say. That'll give you a much better idea of when the misfire is happening, which can help narrow our list of suspects.

Are you noticing any coolant loss?

My mechanic told me the engine was “leaking coolant” but it looks full to me.Here’s live data for timing advance and stft from the same period:

Sorry, it’s not accepting the jpeg from my phone. I’ll have to post it later when I’m at a computer

DIY JoeR wrote:

My mechanic told me the engine was “leaking coolant” but it looks full to me.Here’s live data for timing advance and stft from the same period:

If the Freeze Frame indicates a cold start misfire, I'd start suspecting a blown head gasket.

You can usually catch these by getting the engine HOT, pulling the plugs and allowing the vehicle to sit overnight. Inspect for coolant in the cylinders the next morning.

It usually sets the code after driving for a while.
Here's the timing data:

Here's some freeze frame data:

Freeze frame shows issue with EVAP pressure but manual says that doesn't participate in engine control.

Here's live data on EVAP:

Is that timing PID for the camshaft timing, or is that the Global OBD spark advance PID? :huh: Spark advance would be my guess. That one won't tell us much about the actual mechanical timing.

If that is Global OBD, then the EVAP PIDs won't help us much, either. The Commanded EVAP doesn't look unusual, but the pressure PIDs are very unreliable, especially on Nissan. I wouldn't sweat an EVAP problem right now, especially since the trims are OK on the Freeze Frame data.

The good news is that the Freeze Frame data you posted (which is excellent, BTW ) doesn't necessarily support a head gasket issue. All four are under some kind of load, off idle, at least partially warmed up, and several minutes into a key cycle.

Fuel quality comes to mind, BUT it appears you've refueled at least once between FF#3 and FF#4. If I were you, I'd be tempted to move the #1 coil and plug again. :silly: I know you already did, but ignition is still at the top of my suspect list.

I don't think I can get VVt data.
I drove the car on parkways for an hour on Friday night and the CEL never came on.
Mode6 recorded only 31 misfires on cylinder 1, 2 on cylinder 2, 1 on cylinder 3, and 4 on cylinder 4.
I noticed that all the smog tests were complete and passed so I was able to get it to pass NYS inspection!
That takes the pressure off.
Did I mention that the car has 191K miles.
What are we looking for when switching coil and plug again?

Oh and Saturday morning there was a streak of antifreeze under the car.
Upon inspection it looked like the radiator cap was leaking.
I took it off and put it back on again and that stopped the leak.
That must have been what my mechanic called "leaking coolant".