CC Cleaner didnt work. Defective sensor? P0302

1999 ram 1500 4x4 has been getting this cylinder 2 misfire for over 2 years now. It has went away a couple times for a brief period (less than 2 weeks
each time) but coems back. After I ran 2 cans of cc cleaner and changing the plugs the code was back in minutes. I cleared all codes out after the cleaner and got about 5 miles before it came back. I have replaced the following: cap, rotor, wires, plugs and injector. I did the tsb about rerouting the wires as well. I am at a loss now. Where is the sensor for this and could it be defective? What about the fuel rail? What exactly causes this code to trip? I have 65k miles on the engine so I doubted it was buildup but worth a try.
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Might want to try an egine flush, followed by an oil change with Lucas oil stabilizer, Bardahl 2, MMO or Shaler Rislone in the oil to see if it gets any better.
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Can try that but will be a couple weeks before I can do it.
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Have you happened to notice if the misfire event occurs more at low engine idle (below 1000 rpm) than above? We didn't realize that with my P0307 misfire problem until we got it in the shop and had it idling in gear with some test equip hooked up.
Once we realized that I found I could actually prevent it from happening just by holding a slight throttle pressure whenever coming to a stop. Never let it drop below 900~1000 rpm and the misfire code would never occur. But sit there at 5~600 rpm at a light w/your foot on the brake and the misfire code would happen almost every time. Always the same cylinder (#7).
In the shop idling in gear we could see multiple misfires counting up, typically about 8 per minute, all on cyl #7. That was actually an exciting revelation as it was the first time we finally figured out it was only happening at very low engine rpm, i.e., when decelerating from about 30 mph down to a complete stop, and/or idling in gear. We thought of simply turning up the idle speed, but that would only mask the problem and not fix it, plus then the truck would idle at about 1500 rpm in neutral.
The CC cleaner (1st application) to a hot engine then waiting about 4 hrs before revving the SH#! out of it and taking it out on the tollway for several WOT upshifts made a noticeable improvement tho the problem would still sometimes reoccur (but far less frequently). The second application of CC cleaner (again to a hot engine) and then letting it sit 12 hours (overnight) before revving the sh%! out of it and another 20 mile trip of multiple pedal to the floor upshifts and the problem has so far (3 weeks now) not come back.
I'm not fully convinced it's 100% fixed, but I'm optimistic that we're onto something here.

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I can idle it up temporarily and try this, I have been following these related threads and wondered if I had the same trouble as you. What fixed yours when you found out the trouble?

I applied the cleaner to a hot engine and let sit overnight each time, driving it several miles wot in between. didnt fix a damn thing but cleared a few mosquitos out.
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I honestly doubt that it's "fixed" just that the symptoms have temporarily cleared up following two doses of CC cleaner.
Prior to this we had tried everything, starting with a compression test, replacing the wires, plugs, coil, MAC valve, flushing injectors, swapping injectors, the wiring TSB, etc.
Initially (18 months ago) the problems cleared up for 5-6 months ar a time just with an injector flush, but over time came back (always same cylinder, P0307). Most recently the injector flush was no longer having any effect. Also it wasn't until 6 weeks ago that we woke up to the fact it was only occurring at low engine speed (below 1000 rpm).
The CC cleaner I feel has us at least back to where we were 18 months ago with the problem being temporarily mitigated. I'm hopeful it's gone forever, but we fought it so long and hard that I'm not optimistic.
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RN
"cylinder 2 misfire for"
Swap the #2 plug wire if possible with another wire of the same length. See if the problem shifts!! Bob AZ
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I replaced the wires entirely, and also swapped afterwards, still number 2.

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Did you do a compression check?
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wrote:

A sticky valve likely won't show up on a compression test. A worn guide usually won't either. Nor will a bad lifter, in many cases.
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It won't show up on a leak-down test, but anything that's hanging up a valve will show a lower-than-normal compression. If it's intermittently sticking, well, then yeah - you're shooting blind... but any kind of diagnosis in this case is incomplete without at least a compression check.
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Now this would depend on how bad the valve was sticking now, wouldn't it.

And also would not normally cause a misfire so what exactly is your point? Worn guides also normally cause smoke before they get bad enough to cause poor running.

And that will also not cause a misfire so again, what is your point?
As Tom said, a compression check is also a required test to formulate a valid diagnostic. The valve could be carbon locked which WOULD show on a compression test and for all we know, there could be carbon buildup causing excessive compression that could be causing the spark to be "blown out" indicating a possible weak coil. I would also put the vehicle on a scope to check both the ignition and the injectors for proper operation. Just because the injector has been replaced doesn't mean that it is functioning.
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wrote:

T-Bone. The missfire is apparently very intermittent, and not felt - from what I gathered. A loose valve guide WILL cause intermittent missfire - enough for OBD2 to pick up. A functioning catalytic converter will clean up the oil smoke from one bad guide without much problem. A sticky valve - if not real bad, will also cause an intermittent missfire. As for a bad lifter - it CAN cause a misfire, depending on the mode of failure. If a lifter sporadically pumps up it CAN hold a valve open enough to cause a misfire every once in a while.
And yes, there are many things a compression test WOULD find - but just because the compression test reads OK does NOT mean there are no valve or valve-train related issues.
I've seen ALL of the above cause misfires
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open

I wil try the compression check to see, if nothing noted there then I will be dealer bound then since I dont have a scope.
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