P0301 misfire on cylinder 1.

I don’t understand how our readers determine there is a misfire in the first place. I guess I mean how the ecm knows.

 

Is there a code specific to misfire? I will check back later. Thanks

 

on the crankshaft behind the pulley there is a reluctor ring that has many teeth on it and a place where there are no teeth. On the camshaft there is a similar setup but with only 1 tooth. As the crank and cam rotate the sensors pickup the magnetic field that is broken as the teeth pass the sensor... it is in a analog sine wave form, like ocean waves, there are so many crankshaft teeth wave forms before a camshaft wave form. When there is a mis-fire the crankshaft actually slows down* and the PCM is expecting to see the crankshaft wave form and the camshaft wave form in perfect timing. The PCM knows when #1 cylinder is at TCD is by the crankshaft position sensor. With there being 360 degrees in a circle the PCM is expecting to see a crankshaft TDC wave for every 60 degrees of rotation... 360 / 6 cyl = 60 degrees. 360 / 4 cylinders = 90 degrees. If the PCM is not seeing the TDC wave form where it is expecting at say the 180 degree position on s 6 cyl, then the 3rd cylinder in the firing order is misfiring. This is a generalization of what happens... The programming for this is much more sophisticated than that in that the same cylinder or multiple cylinders have to misfire say 30 times in a minute to set the CEL.

*there is enough play in the cambelt or chain to allow for this. How many degrees of crank/cam timing being off for a misfire detect is an unknown to me.

 

Holy crap. You are one smaht mofo. Thanks a lot. I love what I learn here.

 

Well said well said. I had always wondered what the logic was to the ecu detecting a misfire. Now I know

 

back then it was just a car... my tech buddies in the industry today have to deal with much much more. variable valve timing that works most of the time, adaptive cruise control, fully drive by wire, CAN busses etc. All of this is baby stepping to fully autonomous electric vehicles. No internal combustion engines means no more emmissions or emmissions related warranty claims. the days remaining for auto technitions are numbered.

 

So helpful reading these notes. I have a 2017 Tacoma that twice now has lost power and died when accelerating. Luckily I get to the shoulder, and when I sit a few minutes, it starts back up with no issues. I went to Toyota today after it happened, and they diagnosed the 3rd cylinder misfire is causing the vehicle to shut down. I'm taking it back next week so they can do full diagnostics, but appreciate all of your expertise.
I have had Tacomas for decades and this is disturbing as I depend on my truck.

 

Oh mannnnn, there is nothing more terrifying than an unreliable daily driver... I know exactly how you feel, say a prayer each time you turn the key and every little shudder sends you into panic mode envisioning it dying in the middle of an intersection.... hang in there.....

 

Let’s make a nuclear powered Tacoma. We can put a cold air intake on it for looks