Hello everybody,glad to be here. I need a little help..Working on a 1998 Ram Van 1500 3.9 liter 142,000 miles..I got a missfire code for number 4 p0304..

Things i know

125psi compression , 17 inches mercury , 48 to 52 psi fuel pressure--needle on fuel gauge shakes violently from 48 to 52 , engine is running rough and down on number 4..Injector pulse is normal (checked with noid and compared to others)..Plenty of spark to plug..

Things replaced

Plugs , wires , cap , rotor , cam sensor/pickup , crank sensor..Still missfiring..

So i swapped the injector with another and still a dead number 4..No engine noise (valves,bearings , ect)..Swapped the new plugs and still same..Replaced the new plug wire with a known good one and still the same..

Every time i removed the spark plug it is wet with fuel..Any help would be much appreciated..Thanks everybody..

 

Have you connected a test light across the injector wires yet to see if it's pulsing on and off? There could be a short that is causing the injector to stay open.

 

No i havnt..I used the noid light and also switched injectors..Then i used a stethescope to listen to the injectors and it is clicking fine..

 

I will check the pulse with a test light tomorrow..Anybody else?

 

Anybody had a tone wheel go bad?..

 

Tone wheel?

 

Anybody got a link to the TSB for spark plug wire routing to avoid misfire?

 

Crank Sensor Reluctor Ring

 

I found it,i will check it out..Thanks..

TSB 18-48-98

 

Flywheel...on these engines the flywheel has 6 or 8 notches which trigger the crank sensor, one for each cylinder.