Mechanics

#4 CYL MISFIRE - OHC 3.0 117K MILES

2002 Ford Taurus

Engine runs fine except on the second start-up in the day when the engine runs rough at a stop light (idle) and the engine light flashes. Either I can accelerate through the roughness for about 15 seconds, or turn the engine off and re-start it. The engine light stays on but the engine runs smoothly. Until the next stop light.

OBD code indiates Cyl. #4 misfire.

Wires and sparkplugs replaced at 100k miles for general maintenance. Before misfire was a problem. Lube was wiped on boots at plug and coil for good seal.

Plugs and wires of cyl#4 & #5 swapped but problem did not move to cyl#5.

Fuel pressure measured at 30 psi and should be 39 to 55 psi. Fuel filter replaced but pressure still the same.

Fuel injector replaced on cyl#4. No change.

ECM connector un-plugged and plugged several times to assure good connection.

Where do I go next? : Cry:
Coil, ECM, sensors?
Regards, SailorMan
Avatar
SailorMan
March 12, 2006.



Keep it simple at first, Replace the plug.

Good luck and post back. : )

Tiny
Peppermrj
Mar 12, 2006.
Good morning,

I swapped the plugs and wires between cyl.#4 and #5 but the misfire still occured on cyl.#4.

Any other ideas?

Tiny
SailorMan
Mar 13, 2006.
Was the code PO304? Are there any other codes?

Can you swap coil packs?

What does # 4 plug look like? Fuel soaked, carbon covered, clean and dry?

Fuel injector firing?

Has the EGR valve and port ever been cleaned?

" A code P0304 may mean that one or more of the following has happened: Faulty spark plug or wire
Faulty coil (pack)
Faulty oxygen sensor(s)
Faulty fuel injector
Burned exhaust valve
Faulty catalytic converter(s)
Running out of fuel
Poor compression
Defective computer " Good hunting and let us know. :

Tiny
Peppermrj
Mar 14, 2006.
The fuel pressuer is a little low but it will affect all cyclinders not one. It sounds like you have a bad coil. If i'am not mistake that car has a coil pak get your hands on a spark tester pull the wire out of the number four hole on the coild and place the spake tester in it. Start the car observer the tester if no spark replace the coil pak. And happy motoring. PS if you have spark get your self a noid and plug it in the connector that goes to the #4 injector the niod light should flash if it does good if not you will need to replace the computer or you have a bad wire harness. I see cars and trucks all the time with wiring chewed upi by mice and other wooly verman. ( NOS )

Tiny
NOS
Mar 15, 2006.