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Hi team, which specifically goes out to, MDuncan, Xackley and BlackJKU for your recent inputs when I asked for help with mine.


It’s just a brief update in case you were wondering if I’d solved the issue of the misfire P0306 so on #6 without letting on.

In short not yet. I’ve ordered a bi-directional scanner, specific to Chrysler Jeep, hasn’t arrived yet but anticipate it’s arrival anytime.

Not having one for the time being and reading what you Xackley wrote re’ your O2 sensors, I took the initiative and done the same but in doing so I did make a rookie error, after reading even more on sensors etc. I disconnected all 4, sprayed protective lube into sockets before refitting. Ran like a dream for 15km, but when parking to shop, lumpy rough running all over the place. Not being able to identify and do much at the time, I came back to it after an hour, drove the JK back home which was ok with an intermittent miss here and there, but by the time I’d reached home it ran perfectly again. The EML light was on but this time no code was thrown? Before I go off point, what I read was, was that the 4 wire O2 sensors vent to the atmosphere between the signal wires and protective sheath unlike the 2 wire earlier version which has a small hole in the actual sensor screwed into the manifold.

Hope that helps someone out at least, apologies if that’s common knowledge. In short the erratic running after disconnection and connection of the O2 sensors was self inflicted and the spray lube was interfering with the sensors obviously, Whoops!

While I’m waiting for the box of tricks, I also done a block test just to establish wether or not there’s CO2 in the water jacket, thankfully, a negative, so some good news, we’ll very good!


I’m not sure it’s cured, but it’d be a relief without doubt, but as yet, no code thrown except to say I’ve noticed the tailpipe to be sooted up rather than the clean tan colour it always has been, so running rich, but not so I’d notice in relation to km/litre, all seems good still?

The scanner is always going to be a good addition to the tool box regardless and I n response to Xackley’s previous suggestion I have downloaded the ‘Car Scanner Pro’ he suggested as an additional back up to the ordered scanner. I’m just waiting for the Bluetooth adapter in addition. What I liked about that and what the demo showed was the parameters to look for but in the far right column, the system tells you wether the component test has passed or failed.

I understand that these are for guidance and should direct you and not always be taken literally and that you need a fairly comprehensive knowledge of how all the sensors work in unison with each other and what each one is responsible for, otherwise you’ll just keep throwing parts to the problem still without fully understanding why... even with a scanner.


Cheers guys, I’ll report when and if I learn more. I’m making an effort to see this through to the end, because my internet experience in finding the info I’m specifically looking for is somewhat disjointed. The authors don’t always reiterate the complete facts and the suggestions to a final solution are generally inconclusive if the issue is not found to be a plug or coil.