Missfire My 2001 ford f150 v8 5.4 triton has a 7th cylinder missfire. I have replaced the spark plug twice and the fuel injectors and the coil packs. I also did a compression test and It is good. I still have the missfire after all this someone help me please!!!

could have bad plug wire.fuel injector number 3 wires at connector could have short or open.PCM not firing fuel injector 3 could have intake manifold leak at cylinder 3 could mechanical failure at cylinder 3.

Exchange cylinder 4 and 5 parts with 2 other cylinders and see if the problem goes to the other cylinders.Start with this first.

move the ignition coil to another cylinder and see if the miss fire moves. If so replace that ignition coil. If the miss fire stays on that cylinder it is more likely the fuel injector. Was their carbon on the spark plugs when you removed them? This is indicative that the fuel injector is gummed up.

needs the coil replaced 5.4 or 4.6 triton both do this

honestly it sounds like you have a bad computer. there is a constant 12 volts going to each fuel injector and the computer momentarily grounds each fuel injector to activate, the black smoke is from too much gasoline and the missfire is probably from the injector either hanging open or being held open electricaly. next time it starts to missfire on number 1 cylinder try taking a stethiscope or long screw driver and put it on #1 fuel injector with the engine running and see if you hear a clicking sound. If not try unplugging the #1 Fuel injector. this won't fix the missfire but you can see if the black smoke clears up. if the smoke doesn't clear up with the injector unplugged and you are sure its # 1 cylinder thats missing, replace #1 fuel injector.

MISFIRE ON CYLINDER 2 COULD BE LEAKING INTAKE AT CYLINDER 2 OR DIRTY CLOGGED FUEL INJECTOR AT 2 CYLINDER.REPLACE AIR FILTER IF IT LOOKS DIRTY AND CLOGGED UP AND CHECK TRANSMISSION FLUID LEVEL.IF FLUID LOOKS BURNT SMELLY CHANGE FLUID AND FILTER.

Switch the plug wire with one of the others and if your missfire moves to a new cylinder its a bad wire.

I assume you know the problem is a misfire in #2 cylinder from checking the diagnostics code. Although these codes can be helpful in narrowing down a problem they lack specific details. In the case there are several possible items that could trigger the engine fault code P0302

These include:

• 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

Before you spend any money to resolve this you need to narrow this list down even more. Start by pulling the plug. Do a image web search on "spark plug diagnosis". This will give you pictures of plugs with a variety of problems to compare with yours and give you an indication whether or not the plugs need replacing. Next if possible switch #2 plug wire with another. Make sure you switch both ends (coil end and spark plug end) of the spark plug wire.
These are the no or low cost options. Beyond these you will need to start replacing items like the Ignition Coil and O2 sensor.
If you are still having the problem after checking and/or replacing the items listed above, your next step is a compression test on #2 cylinder.
If you get to this point please repost here with the results with the wires and plugs and I will give you the steps to follow with compression testing.
Hope this helps.

misfire only comes from the coil packs.. replace them

If the plug and coil are good and you have good compression you should probably replace the cylinder 8 fuel injector.