Hey Everyone,
I'm running out of ideas on why my Dak is crying about a p0304 misfire on cylinder 4. Any advice much appreciated.

Things I have done:
New fuel pump (was having long startups)
New cap and rotor
New cables
New fuel injectors
New Sparkplugs
Compression test (pass all either equal or 1 to 3 PSI difference)

Next to do:
Test connector with a Noid Light possible connector issues.

Other than that I can only think of computer issue and need it replaced. I just cant believe it would be because I have absolutely no other issues, but who knows.

Thanks,
Peter

 

If it's only showing cylinder 4 and not 2 or 6, that's a little unusual and could justify checking with a noidlight.

If it at any point gives you 302 or 306 as well (which should be accompanied by a 300), then start looking at the upstream O2 sensor on that bank and/or the crank position sensor.

I was getting all kinds of intermittent multi-cylinder misfires. I replaced the crank sensor with a box store one and they maintained. After throwing all the diagnostic tools at the world at it and finding nothing wrong, I put a mopar crank position sensor in. Did a PCM reset and poof, no more codes.

 

Ok so Noid light First

I only have that one p0304 but could possibly be related to:
Upstream O2 Sensor
Camshaft Positioning Sensor

I will check it out tonight. Thanks for the reply.

 

Update:
Replaced the #4 fuel injector connector after testing with Noid light. It seemed like it was working before replacing the connector but I just noticed the female pins were a little scuffed.

Things I have done:
New fuel pump (was having long startups)
New cap and rotor
New cables
New fuel injectors
New Sparkplugs
Compression test (pass all either equal or 1 to 3 PSI difference)
Replaced #4 Fuel Injector Connector
Replaced Crankshaft Positioning Sensor

I reset the computer and got the P0304 #4 Cylinder misfire again after a couple weeks. At this point all I can think of is a faulty computer. Can anyone please let me know if there is something else I can look into?

If it is a faulty computer, anyone recommend where to purchase a computer?

Thanks,
Peter

 

You got a genuine dealer mopar crank sensor, right? I had issues with the box store ones (it's because of how the flexplate is designed on only the V6)

Did you change spark plug wires when you did the plugs/cap/rotor? Could be a bad wire.

That's all I can really think of. I don't know of anybody from the online world in the LA or San Diego that would have an MT2500 or DRB3. A shop will charge a limb to try and chase down such an odd and rogue issue.

 

I was having that an changed everything including plugs cap rotor,,plug wires ,,tested injectors an wiring to them an also used seafoam in intake,fuel an oil as directed,cleaned out the idle air controller too..I no longer am getting that code..As i was cleaning out the upper intake -seafoam,the code changed to a different cylinder till i reset it. Maybe trash in it ..3weeks now no codes.
Be sure the pcm harness is secure too..

 

Yes Mopar on the positioning crank sensor and changed cap, rotor, wires and cables all within a week.

Ok thanks for your input.

 

Is it still happening?
Switch the injectors ,do a full reset w battery disconnect an holding key forward method..then hook back up /restart an see if code goes to that other cylinder /injector..

 

I have done all you did except for sea foam. I just did it today and put 1/3 in engine oil, 1/3 in brake booster and 1/3 in gas tank. I did order the spray sea foam to put through the throttle body, hopefully will get to do that in a couple days.

I checked the ecm cables and all are good. I disconnected and reconnected just to make sure. I'll let you know what happens with the spray in the throttle body.

 

Yeah still have the cylinder #4 misfire but well see what happens with the spray sea foam.

I can definitely feel the difference running a little better using sea foam in the tank, oil and brake booster.

Did you spray from the intake tube before the throttle body?