09 Wrangler Unlimited Cylinder #2 misfire

the code not presented P0302
means this in pure physics (best)!
it means the piston velocity on #2 was slow.
the PCM measures the rate of change, at firing. (of each piston by federal laws,OBD2)
and if slow, that means its weak and means.
weak combustion ! #2
it does not mean only spark , see?
weak has 3 major failure paths
bad compression
bad spark
bad fueling. (in that order)
how ever statically, skipping tuneups is #1 cause.... of misfire for 100 years now. the code not presented P0302 means this in pure physics (best)! it means the piston velocity on #2 was slow. the PCM measures the rate of change, at firing. (of each piston by federal laws,OBD2) and if slow, that means its weak and means. weak combustion ! #2 it does not mean only spark , see? weak has 3 major failure paths bad compression bad spark bad fueling. (in that order) how ever statically, skipping tuneups is #1 cause.... of misfire for 100 years now.

Given.
only one code is stored,and resetting it comes back driven....
where do you start, well that is a long story and book, (there are vast books on topic)
ill not do one here.
what did the spark plug look like , before changed out.
black, oil soaked, green with antifreeze
white, or tan,? dripping in fuel, or looks normal. this is like the fist thing.
if the HV wires from coil pack to the plugs
at about 100k miles.
id even inspect every inch of #2 wire.
and make sure its got 3k ohms resistance per foot, not infinity. I run NGK mag wires.
they read 0ohms but are reactance wires.
then if all that fails, I check compression on #2, 120-150psi is spec, sea-level reads max. less in Denver CO.
ok spark good, compression good.
i then scan it , using live data
i then look at all PID data for wrong readings. RTM
this is covered in all ASE classes
and not something I can cover in one page.
I look at pendings too.
and at the freeze frame for P0302, to see of other key parameters read wrong for that.
ECT reads 180F or more.
O2 sensor works at IDLE and swings,
and swing centered on 0.45vdc. fast.
if not, I work that issue.

this post is for you and other JK owners
so if its too long, others will find it useful.
(read the chapters on how misfire monitors work for best results) Given. only one code is stored,and resetting it comes back driven.... where do you start, well that is a long story and book, (there are vast books on topic) ill not do one here. what did the spark plug look like , before changed out. black, oil soaked, green with antifreeze white, or tan,? dripping in fuel, or looks normal. this is like the fist thing. if the HV wires from coil pack to the plugs at about 100k miles. id even inspect every inch of #2 wire. and make sure its got 3k ohms resistance per foot, not infinity. I run NGK mag wires. they read 0ohms but are reactance wires. then if all that fails, I check compression on #2, 120-150psi is spec, sea-level reads max. less in Denver CO. ok spark good, compression good. i then scan it , using live data i then look at all PID data for wrong readings. RTM this is covered in all ASE classes and not something I can cover in one page. I look at pendings too. and at the freeze frame for P0302, to see of other key parameters read wrong for that. ECT reads 180F or more. O2 sensor works at IDLE and swings, and swing centered on 0.45vdc. fast. if not, I work that issue. this post is for you and other JK owners so if its too long, others will find it useful. (read the chapters on how misfire monitors work for best results)