scan code say #4 cly.missfire

[ridenby]

was looking at cows today,with my mother,got hung in mud.in process of getting unstuck moter starts missing,check engine light on,get out of mud shut moter off.restart,no miss.go to buddy,run scan tool,says #4 missfire.now 3-4hrs.later miss is back,if i turn lib.off,restart,no miss. wonder what the heck i have done now?

 

[Dave]

You got a P0304 code then??

I have a 05 FSM and it says the following for troubleshooting misfire code.

1) spark plug

2) dirt in fuel system

3) burned, warped or pitted valves......(hope not)

4) faulty coil pak.

Check/or change the plug (or all of them) and try swapping 2 of the coil paks around to see if the code moves or stays on the same cyl. Change your gas brand. Make sure the wireing connections to the coil pak are tight. That is a start.

Dave

 

[ridenby]

thanks Dave,changing plugs in morn,got extra coil,thinking fuel.kind of acts like xj did on some brands of fuel,found some info on L.O.S.T. about setting cei.

 

[Ken]

My 05 had the same code but was #1 cylinder I have the 4 cylinder engine Replaced the plugs but the same code came back changed the plug wires next problem gone .
So may want to change the wires as well.

 

[ridenby]

3.7L ,but thanks,changed plugs,replaced coil on #4,so far so good,knock on wood.

 

[kylewilley]

I know this is completely irrelevent and unhelpful but I have to admit I giggled when you said "moter"

 

[ridenby]

yeah,spelling is not my strong suit.

 

[Mangate]

What I want to know is how the PCM detects the missfire.

 

[ridenby]

Black magic

 

[ShafferNY]

What I want to know is how the PCM detects the missfire.

Good question. I've wondered that too.

It must detect it via the cam or crankshaft position senor. It's the only logical way I can think of.