Replace the plug just for the hell of it. They are only a few bucks. Another thing you could do is move 2 plug wires around. Change them at the plug and the cap of course. Say move wire 1 to wire 2 and wire 2 to wire 1 and see if your misfire is now on cylinder 1. That will tell you if you have a defective plug wire. If it's that cold id also recomend using dielectric grease on the tips of the plugs where the wire snap on as well as the terminals on the cap.

 

i think there is a couple of other factors in the sensing of misfires, i just am not sure what all they are, i know that in order for an obd-II computer to detect exactly which cylinder it is it uses several sensors; if you can find out what they all are (o2 is one of them), start by tracking those down and ohming them out or having them tested;
as far as it goes, if you're not noticing a rough idle or a miss at any time at idle, then it will most likely be a sensor

 

>jeep95xj I've already tried substituting the cylinder #2 spark plug and wire from another symptom-free cylinder and the code still came up just for that one cylinder. I actually put some more dielectric grease on the spark wire boots when I was double checking everything the other day.

>Absolutexero I was curious about what those sensors would be... no one I've talked to so far seems to know or remember which sensors could be suspected.

I really appreciate your input guys!

 

How's the play in the distributor shaft? Might need a camshaft sensor.

 

Swap the suspect fuel injector with another one and see if the problem moves.

 

Camshaft sensor!

 

Miss-fire at cylinder #2 means the computer is reading the camshaft sensor, fuel injection, and spark-plug firing, with the spark plug not firing when it should. I do not know what you changed, referring to the spark plug wires, but I agree with a previous post. It is cheap to replace the spark plug.
Not as cheap but the next replacement would be the spark plug wire.
Last, but probably more to the point, the ECM. I doubt the camshaft sensor is off, as it is working for the other 5 cylinders.
Good luck, and please let me know what was responsible for the misfire.

 

Thanks for the responses!

I will check on those suggestions and post back with what my findings.

 

check out the injector plug, i had that problem weeks ago, i changed everything and it was just a dw40 think....

 

i changed everything and it was just a dw40 think....

What? Are you referring to spraying wd40 into the injector electrical ends to keep out any moisture?

 

Just an update, the weather has been pretty lousy here in MA: below zero, snowing, etc... So I haven't been able to check much of anything. I've still been running the fuel injector cleaner through the tank and I haven't gotten any codes back yet.

 

I just wanted to thank everyone who posted. When I started this thread, I had decided to run one more bottle of fuel injector cleaner. Since then, the light hasn't come back on and everything has been pretty smooth so far. I'm guessing it may have been a dirty injector.

 

It's back...

*Update*

Since my last post, I have checked the Distributor shaft and found no play. I had also ran a bottle of fuel injector cleaner and the problem went away for a few weeks.

About a month ago the I got the Check Engine Light again. The same P0302 code came back.

So I went ahead and decided to change out the Cylinder 2 Fuel injector and all of the o-rings for all of the injectors while I was at it. I cleaned everything out and reinstalled the injectors and fuel rail. The code was cleared after I unplugged the battery while performing the injector swap. After that the light stayed off for a couple more weeks.

This morning the code came back after a minute or so of idling after a cold start. I still have the same symptoms I had from the beginning. There is no noticeable misfire during idle or driving. The RPMs at idle are steady at ~600rpm.

I'm stumped at this point . Do you guys have any suggestions?

 

Have you tested compression?

 

No, not yet. If it were a compression problem wouldn't there be a noticeable misfire while driving?

 

Probably, but you never know. Also, how were the plugs? Did it ever look like that cylinder might be burning oil?

 

I've had the spark plugs out a few times and all of the plugs looked fine. There were no visual signs of considerable oil burning.

I remember even removing and inspecting all of the spark plugs immediately after the Check Engine Light came on one morning. The spark plugs were fine.

I'm running Autolite Double Platinum APP985 plugs with a .035" gap. I've been running them for about 6 months now.