DTC P0304 - #4 cyclinder misfire

[FSTMRFR]

Hey all I just recently got the code, the truck is STOCK, and has 170,000miles on in and never had an issue until now. It starts to shutters under mild acceleration and progressively gets worse, but its sort of intermittent also, but does it more often then not. The check engine light flashes also. Please help me out on this one..I do not want to spend a bunch of money...

truck is a 5.0 AWD...if this helps

Have any of you expierienced this???? please help!! I need my vehicle....

 

[manaen]

yes, check your wires and plugs. When was the last service on teh engine?

 

[FSTMRFR]

they plugs and wires were replaced like 3 months ago....

but I will check they anyway....

 

[Turdle]

Hmmm-try swapping the coil packs with each other
-reset the pcm and drive it.
I'd like to see if the code moves to another cylinder.

 

[FSTMRFR]

Hmmm-try swapping the coil packs with each other
-reset the pcm and drive it.
I'd like to see if the code moves to another cylinder.

ok I will try that...

I already swapped the plug and the wire separately, and still same code....

 

[manaen]

You can also test the resistance of the coil pack to see if it is dead

 

[FSTMRFR]

I check the resistance of that wire and got 8.55 on at 20K setting...I believe that means 8550 Ohms of resistance if this is correct. I know that the resistance is supposed to be 1000 Ohms of resistance per 12 inches of wire, so on a 1 1/2 foot wire it should be no more than 1500 Ohms...

I also checked cyclinder #5 wire (mainly cuz it was the easiest to get to) and found that 5.23 on the 20K setting on the multi meter as well, and seemed as if that one were very high as well.....so I guess my question is that really 5230 Ohms of resistance???

None of the wires would read on the 2K setting, and I guess that they are all more than 2000 Ohms of resistance, which is bad....

let me know if this is correct or not....

 

[FSTMRFR]

You can also test the resistance of the coil pack to see if it is dead

how do I check that...I figured I could do it the old fashioned way and leave the wire unpluged and zap myself...that is what I was going to do...but it I could avoid making myself and the coil pak a homemade pace maker that would be great!! LOL

 

[Turdle]

Which spark plugs are in there?

The #4 wire is the longest in the set-I think they are fine.

have you swapped the coilpacks yet? It would take about 5 minutes-and tell you where to focus your attention--

 

[manaen]

I assume all the wires look good and there are no rub marks on the casing which could cause grounding?

did you swap the pack yet like Jon said?

I can't find my tech manual to see what the resistance should be between the leads, but if you test the pack and it has 0ohms or no reading you know it's bad.

 

[FSTMRFR]

Which spark plugs are in there?

The #4 wire is the longest in the set-I think they are fine.

have you swapped the coilpacks yet? It would take about 5 minutes-and tell you where to focus your attention--

I really do not know about these coil paks, I have never messed with a car with only 2 coil packs....Do I just swap the wires to the correct cyclinder, or do I have to change the input wires and the sparkplug wires as well....???

 

[FSTMRFR]

I assume all the wires look good and there are no rub marks on the casing which could cause grounding?

did you swap the pack yet like Jon said?

I can't find my tech manual to see what the resistance should be between the leads, but if you test the pack and it has 0ohms or no reading you know it's bad.

do I check them when the vehicle is running or static?

 

[FSTMRFR]

ok...now I am REALLY confused....

I swapped cyclinder # 4 with wire #8 and cyclinder # 4 spark plug with # 5 plug, and planned on clearing the codes, and see if the code changed to another cyclinder, so I could be exact on what the cause was....

and when I did that, the problem went away....no shuttering what so ever....like I said I am really confused......

I can make a guess at this....maybe the plug is going bad, and the wire is going bad...and collectively they were making the cyclinder not fire properly....

and now that I split the problem, and put known good stuff in that cyclinder it is acting fine....does this sound like something that could happen???

I will monitor it for the next couple of days, and see what it acts like when it is stone cold in the morning.....

 

[FSTMRFR]

Which spark plugs are in there?

The #4 wire is the longest in the set-I think they are fine.

have you swapped the coilpacks yet? It would take about 5 minutes-and tell you where to focus your attention--

spark plugs are autolite, non Precious metal plugs...in other words, copper core....I do not know the number on them...I really did not pay attention to it...

 

[Turdle]

ok--here's what I would do--
disconnect your battery- cable(to reset the code)

number your park plug wires with a sharpie, right on the coilpack clip ends-

then-disconnect the electrical connector on each coilpack.
disconnect all spark plug wires from coilpacks-
remove the 8-5.5mm (?) screws -4 on each pack-
swap coilpacks-place for place.
re install screws
reconnect the wires-using the label on the coilpack as a guide-
reconnect the coil pack connectors-

re connect the battery- cable

run engine until the check engine light illuminates-

read code

post results-

If the code remains the same-don't be mad, as you have narrowed it down rather easily.

 

[FSTMRFR]

ok...now I am REALLY confused....

I swapped cyclinder # 4 with wire #8 and cyclinder # 4 spark plug with # 5 plug, and planned on clearing the codes, and see if the code changed to another cyclinder, so I could be exact on what the cause was....

and when I did that, the problem went away....no shuttering what so ever....like I said I am really confused......

I can make a guess at this....maybe the plug is going bad, and the wire is going bad...and collectively they were making the cyclinder not fire properly....

and now that I split the problem, and put known good stuff in that cyclinder it is acting fine....does this sound like something that could happen???

I will monitor it for the next couple of days, and see what it acts like when it is stone cold in the morning.....

 

[Turdle]

cool. if the problem goes to 5 it's the plug-if it moves to 8 it's the wire-if it stays the same it's the coilpack or fuel injector--

brilliant!

 

[FSTMRFR]

cool. if the problem goes to 5 it's the plug-if it moves to 8 it's the wire-if it stays the same it's the coilpack or fuel injector--

brilliant!

correctamundo!!