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Need help here, I have a 2005 Dodge Durango that intermittently will set a P0304(misfire cyl 4). But it sets the code only at start up. It will run rough for a second or 2, set the code then runs perfect. And it only does it once and awhile, otherwise it runs great most of the time. Have checked for intake leaks, moved the cop, and plug to other positions still no.4 sets when it does. Maybe injector but so intermittent wanna make sure before tear in that deep. Resistance’s check fine(within ohms of each other). Also noticed seams to be more frequent with A/C on. Any idea’s would help, starting to get brain locked been staring at this so long?
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Try doing a power balance test with the injectors.
http://www.ericthecarguy.com/faq/solving-automotive-performance-issues?start=3#PowerBalanceTesting
OK, balance test didn’t revel much because when it did mess up, it would clear up before I could do much. But freeze frame data says it happens at CTS=same as ambient fuel=open loop RPM=338. So like I said I think its setting code at start up then after 3-5 seconds it clears up. And it is so intermittent but does seam to be more frequent with the A/C on. Maybe a crank sensor? but then why always #4? No detectable vacuum leaks around intake excellent compression?? Listening to the injector it sounds fine(like all the others). I think scannerdanner has something about checking current flow on injectors might try that. maybe just a slow/sticky injector at start up.
[quote=”r8er4ever” post=102089]OK, balance test didn’t revel much because when it did mess up, it would clear up before I could do much. But freeze frame data says it happens at CTS=same as ambient fuel=open loop RPM=338. So like I said I think its setting code at start up then after 3-5 seconds it clears up. And it is so intermittent but does seam to be more frequent with the A/C on. Maybe a crank sensor? but then why always #4? No detectable vacuum leaks around intake excellent compression?? Listening to the injector it sounds fine(like all the others). I think scannerdanner has something about checking current flow on injectors might try that. maybe just a slow/sticky injector at start up.[/quote]
What motor are we talking about here???
4.7 and been reading story’s of rocker arm’s fallen out but that would seam more permanent and not intermittent.
What kind of plugs are you running? i have seen those engines raise hell if anything but copper core plugs are used in them…
I would also check to make sure all your connections at the coils and at the battery are clean and tight. Dodge PCM’s are know to through mis-codes when it has weak voltage. Also i would have your battery tested as well.
If all that checks out then i would have to lean towards the coil pak itself starting to fail or the wires leading to #4 got damaged some how.
I believe Champion Copper Core’s(have to look tomorrow), that is what the part’s store said is OEM. It’s a 2005 so it has a COP(coil on plug) system, but have moved it(coil) to #1 and moved plug to #2. Only thing haven’t moved yet is injector, but that is because it is so much more labor intensive to move unlike the others. I guess gotta try moving that now. Because code always sets #4 when it sets. Maybe I am reading more into this then I should but the freeze frame data setting code at under 400RPM’s has me curious.
Are you adding coolant? I have seen leaking head gaskets cause your problem as well as worn valve guides or valve seal. Coolant or oil on the spark plug tip until it burns off.
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