Our 2009 Cube SL which my brother bought new had a fresh free tranny at 92K and suddenly, it began to exhibit intermittent rough idling and below-average gas mileage around the 126K mile mark. Thinking a tune-up is due, I figured it probably needed a new set of plugs to which I ended up also getting a new set of 4 ignition coils, OEM spark plugs, changed the oil, tranny fluid, and refreshed the car's K&N air filter.
Despite all this, after 2 weeks of real or imagined "better" performance, the old gremlins were back with a vengeance. Now, traffic light take-off from a standstill began to have a telltale clicking noise I've never heard before, it sounded like there was a hole in the exhaust pipe somewhere, maybe on the top part of the pipe where it is harder to see.
Hmmm, you know, I have been procrastinating about getting an OBD reader (OBD-On Board Diagnostics), a tool no self-respecting DIY mechanic would imagine being caught dead without. Twenty bucks Plus tax later, I made my acquaintance with the most unassuming, diabolical, and persistently stubborn DTC (Diagnostic Trouble Code) I wouldn't wish on any Nissan Cube owner friend or enemigo: DTC code P0301; Mis-fire Cyl 1.
Commonly explained by the supposed presence of a hole, gap or opening somewhere within or without the confines of your MR18DE engine's metal, rubber, and plastic plumbing that is causing the engine to fail in its ability to hold a vacuum. Imagine a perfect blend of air and atomized gasoline droplets about to be compressed and ignited without a bang!! Well, it could be something as simple as a dirty Mass Airflow Sensor or MAF for short (no), Throttle Body (maybe, and I cleaned it anyway, you never know, still a maybe), PCV valve (you mean Positive Crankcase Ventilation, nah!). Valve cover gasket? One of the ten thousand little black hoses decorating the engine block, we can soap it and look out for bubbles. Maybe there isn't any fuel reaching the cylinder, Fuel Pump? Overhauled with a new motor. Fuel filter, getting warmer. Eureka! A clogged Fuel Injector, replaced Cylinder 1's FI, nada. What?!? Intake Manifold Gasket, nein.
Does anybody see the light at the end of this dark, haunted Money Pit?
Then you should really be thankful it is not a P0300 - Intermittent or Random Cylinder misfiring, really? Cyl 3? Cyl 5? Your engine has only 4 cylinders. I got it! Let's duct tape the entire Black plastic air intake contraption (everything before the Air Filter). What an inspired hypothesis... nope.
Unfortunately, you can't give up. Camshaft Position sensor? No. Crankshaft Position sensor! No! Knock Sensor? I forget, but at one point I was tempted to buy a fog or smoke machine. Just pipe in the smoke or fog output to one of your engine vacuum hoses and the smoke will visibly reveal where the ****** are in your engine's vacuum realm.
After almost a year, the engine only slightly improved by a new MAF sensor, I began to dread the thought of being defeated by this technical puzzle and the bad memory of a malfunctioning distributor shaft in my old Nissan 200SX came back to life.
Like Thomas Alva Edison before me, I now knew 8,561 ways how NOT to fix a P0301 DTC code.
Leaving no stone unturned, I chanced upon a YouTube video about detecting or testing to confirm if you have a leaking head gasket. Head gasket? What's that? Since I didn't know, the thought that I was ignorant about this part of an automobile made me rise to the challenge. And the rest, they say, is history.