As you know your code is a missfire on number 4 cyl, you may have a bad harness that plugs on the injector, crossed plug wires (not likely but can happen) or a bad PCM. Below you will find wiring for number 4 injector as well as your code read out.
http://www.chiltonlibrary.com/content/images/WD/Ford/194/WD_Ford_194642.pdf
Trouble Code: P0304 (3.8L V6 VIN 4 Std)
Cylinder Number 4 Misfire Detected
Print this code data
Number of Trips to Set Code: 2
OBD II Monitor Type: CCM Details
Indicators: MIL Details
DTC P0136, P0156, P0171, P0172, P0175, P1130 and P1150 not set, engine started, engine running under positive torque conditions, and the PCM detected a misfire a misfire in Cylinder 4 during the 200 revolution (Catalyst) or 1000 revolution (High Emissions) period. Note: If the misfire is severe, the MIL will flash on/off on the 1st trip!
Possible Causes:
http://www.chiltonlibrary.com/content/images/WD/Ford/194/WD_Ford_194642.pdf
Trouble Code: P0304 (3.8L V6 VIN 4 Std)
Cylinder Number 4 Misfire Detected
Print this code data
Number of Trips to Set Code: 2
OBD II Monitor Type: CCM Details
Indicators: MIL Details
- MISFIRE Details
- MIL Details
DTC P0136, P0156, P0171, P0172, P0175, P1130 and P1150 not set, engine started, engine running under positive torque conditions, and the PCM detected a misfire a misfire in Cylinder 4 during the 200 revolution (Catalyst) or 1000 revolution (High Emissions) period. Note: If the misfire is severe, the MIL will flash on/off on the 1st trip!
Possible Causes:
- Air leak in the intake manifold, or in the EGR or PCM system
- Base engine mechanical problem that affects only Cylinder 4
- Fuel delivery component problem that affects only Cylinder 4 (i.e., a contaminated, dirty or sticking fuel injector)
- Ignition system problem (coil, plug) that affects only Cylinder 4
- TSB 02-16-2 contains repair help for this code (LS & T-Bird)
- TSB 03-14-4 contains repair help for this code for COP ignition
