Narrow down P0301

M

Mikey

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Mar 6, 2024
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Las Vegas
Hi folks.

I have a 2017 that threw a P0301 a couple months ago after it suddenly started to run *really* rough. It was obviously a misfire.
The spark plug was badly fouled and replacing it cured it.
A week or so ago it kinda started intermittently running a *little* rough. It didn't seem like it was missing, I thought maybe it was just crappy gas.

Yesterday, engine light came on and the JScan said it was P0301 again.
This time, it isn't running horribly like the first time.

Between forums and YouTube, I've seen it could be Crank pos sensor, cam pos sensor, 02 sensor, pcv, coil, injector, etc.

My question is: what is a good approach to narrow it down?
I'm going to swap the #1 and #2 coils and see what happens.
Maybe swap the #1 and #2 injectors as a second test if the coils are good?

Since it ran fine for a couple months, it seems to me that something else is fouling things.

Rather than pull out the parts cannon, I'd like to be systematic approaching this.

Any thoughts?

Thanks,
Mikey
 
In saying crappy gas I didn't mean bad or stale, I meant I maybe put the 10% ethanol in without realizing.
 
Putting in 10% ethanol will not in any way cause problems for your engine. That's urban myth. Like "you can't make power through cats".
Swap the coils. Then the injectors. If the fault doesn't follow to the new cylinder, then it's almost certainly one of the sensors. There's no easy way to test them, so just replace them. I'd do them all, but you can certainly do them one at a time.
 
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