Hey Scotty,
I own a 2016 Nissan Versa Note 5 spd manual and I'm encountering misfires. My scan / diagnostic app tells me that I have a P0303, P0103, U2821 and P219C. It also likes to switch back and forth to a P0203 and a P0103. The CEL blinks. So, I've already changed the spark plugs, replaced coil 3 and a new MAF sensor. Even switched back to a paper filter. No vacuum leaks before the MAF sensor or after.
Still given the same codes.
Seriously thought I might have a faulty ECU.
Took the car tot he dealership to have it diagnosed. $140 later, was told that they're reading P300 and P0301. C1 had 311 misfires. Wanted to charge me $600 just to remove the intake manifold and further inspect C1. Something I can do in less than an hour. But yeah, none of the codes I've been reading. No longer get the injector code. I use Real Dash for real time information via a BT OBD2 adapter.
I replaced all coils and checked the connectors. Couldn't find any grounding issues. I'm stumped.
less changing, more targeted testing and deduction. Check if the engine is getting what it needs to run. Verify the spark plugs are sparking visually. Verify fuel pressure with a gauge. Verify fuel injectors.
Only two cylinders are misfiring right? Use that to your advantage. Instead of replacing everything, swap the coils, or swap the injectors with known good cylinders.
I would verify it does have the factory correct spark plugs. Nissans are very temperamental to factory plugs and since luckily the cylinders are side by side I would check compression and cylinder leakage to eliminate a mechanical problem
