Misfire code P0302

A misfire can be caused by bad compression,poor spark, and or a faulty fuel injector.

Try shifting the plugs around, look close at the one from number two. Does it look different than the rest? Next run a fuel pressure test, low pressure can cause a mis, especially when you are at higher rpm as the pump cannot keep up (35-45 psi key on engine off).
When was the last time the fuel filter was replaced? A partly clogged filter could also restrict fuel flow and cause a misfire. (test the pump output, should get one pint in thirty seconds)
Lastly, run a compression test, high mileage, it is possible a valve is not sealing good and causing it to show a misfire in that cylinder or even a minor head gasket leak between three and four would show as a number three mis.

steve w. filter was changed about a month ago. i will be replacing plugs with motorcraft plugs, i will test fuel pressure this weekend.

Hey ANTHONY,

It sounds like it could be a dirty mass air flow sensor as well. Here is guide on how to clean it.

https://www.2carpros.com/articles/mass-air-flow-service

Please let us know happens so it will help others.

Best, Ken

I replaced mass air sensor cleaned with the cleaner and replaced the harness, I know isn't good but went to wrecker yard when I installed the mass air flow it for rid of my p113 code and cleared the rough idle, this weekend I put in sea foam in tank, replaced the 2 spark plugs to that cylinder then had a notion of tapping injector. Cleared the code drove truck around for maybe 1/2 hour no code I then stopped at a stop sign went to shift go check engine light started to flash then became solid with that code again. It seems that the code doesn't flash as fast as it used to used to go maybe 6 minutes till it started to do it this was the longest it went before flashing.

Oh and yes I did look at the plugs they look almost the same as the new one, no carbon, no moisture, no oily residue and this being 2 plugs per cylinder im not sure which side it is causing the problem. Also hopefully someone will know does this have a crank shaft sensor and where it is at? I can't locate it at all

Hey ANTHONY,

Here is the sensor location and a guide to help you know what you are in for when changing it.

Please let us know happens so it will help others.

Best, Ken

so today i rechecked all connections, all were good reset the check engine light took truck for drive put gas in to it took it on freeway at 65 let up drop to 40 then jumped back on it at 65 no check engine light. went up and down different streets different speeds etc. nothing till i got near my place and it kicked back on.thought well maybe idle it too high adjusted that and a gain drove around for quite awhile it came back on again, so then i reset the check engine but this time i swapped the relays around and no even 20 feet down the road check came back on. so question is the fuel relay possibly causing this misfire on cylinder 2?

should say i drove it about 40 mins with no check engine light on

Hey ANTHONY,

this only leaves the fuel injector that must be causing the problem. Here are a couple of guides that will show you how to replace it and how to test it once its out.

https://www.2carpros.com/articles/how-to-test-a-fuel-injector

and

https://www.2carpros.com/articles/how-to-replace-a-fuel-injector

Lets us know,

Best, Ken

Now I did buy a stethoscope and the injector was opening and closing sounded good, now is it possible that the o2 sensor is going out or carry converter clogging up

O2 and Cat would both effect all cylinders not a single cylinder. Injector sound doesn't mean much if the internal screen or nozzle at the tip is blocked, even partial blockage will cause a misfire as it leans out that cylinder.

ok so i'll need to remove the injector is it best to remove the the riser to the throttle body or can work it out easily

Drain the fuel pressure out of the rail, remove the riser (I have had a couple early 2.3s where you could get the rail off the injector without removing it so you can try) remove the fuel rail, pull the injectors. clean and test. Reverse the process to reinstall. Apply some clean oil to the O rings to get them to seat easier.

This may sound dumb but I checked the spark grin a new coil I bought when This all started in was able too hold a screw driver over the open terminal and saw spark jump on to a screw driver now I didn't see that I hooked up a wire with an old spark plug and see spark coming out of the plug boot nothing out of electrode.
So wondering if coil pack is bad

Regards,

Anthony Digilio

Spark out of the boot but not at the plug sounds more like your used plug is bad. Get a spark tester and test each wire. Will easily tell you if you have a problem.

ok seeing how i have problems with the number 2 cylinder i went and bought a injector and replaced it, I started the truck it bubbled and farted then died, not it won't start at all it'll fire but cut it's self off. am i supposed to purge the line? I started by loosening the gas cap removed the relays, disconnected the battery and pushed the fuel valve
took off throttle body , then started removing bolts to intake to upper half off after many cuss words at on bolt that wasn't coming loose i decided to loosen the bolts on the fuel rail i had enough room to pull the # 2 injector out, replaced the injector, and re seated them, re tightened down all the bolts and replaced the throttle body, replaced the pcv valve seeing how i broke the other one.

Double check that you put the plug wires on correctly. Did you replace the intake gasket? If you didn't remove the riser and just moved it without a new gasket you may have a vacuum leak. You can check that you have fuel at the schrader valve.

i checked the firing order all is correct did not remove or even move riser last bolt was securely tight, so hopefully on sat i can check the valve, maybe just need to crank on it a few times to build up pressure? and i'll recheck throttle plate gasket so i can make sure the vacuum line coming off throttle is secure in there

I should note that originally when I started taking things apart I removed the relays and opened up cap to the tank also noticed when I depressed the valve there was fuel coming out relieving the pressure, is it possible the kill switch was tripped or a bad relay?

Bad relay is possible. Seen more than a few that were borderline on powering the pump. Toss a pressure gauge on it. Most have a way to purge the line to the gauge, you could use that the be sure you are getting fuel. Just turn the key off/on a few times OR jump the pump directly to power.