P0304 error
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P0304 error
Hi guys,
Hopefully someone can give me a place to look as I’m running out of ideas on this issue. First, I bought this truck used and have no previous history on it. Now what happens I get error P0304 which is a miss fire on cylinder 4. I’ve replaced the spark plugs, spark plug wires and coil twice (one was an aftermarket and now has all Motorcraft parts). I brought it to my local mechanic as it was getting little more that I can handle. Now they looked it over and I was told that they can’t seem to figure out why or that is causing this issue. From what I was told they moved the spark plug wires to a different spark plug and the issue followed. He replaced the fuel injector to test out if it would fix, which it did not. My question is what else could be causing this issue, do you think the computer is bad? What I’m being told it’s only gives out a low spark. What controls the spark on the coil, the computer? Do you think it’s the wiring to the coil pack. The truck runs fine until you get to speeds around 50 to 55 and that’s when you feel the miss fire.
Hopefully someone can give me a place to look as I’m running out of ideas on this issue. First, I bought this truck used and have no previous history on it. Now what happens I get error P0304 which is a miss fire on cylinder 4. I’ve replaced the spark plugs, spark plug wires and coil twice (one was an aftermarket and now has all Motorcraft parts). I brought it to my local mechanic as it was getting little more that I can handle. Now they looked it over and I was told that they can’t seem to figure out why or that is causing this issue. From what I was told they moved the spark plug wires to a different spark plug and the issue followed. He replaced the fuel injector to test out if it would fix, which it did not. My question is what else could be causing this issue, do you think the computer is bad? What I’m being told it’s only gives out a low spark. What controls the spark on the coil, the computer? Do you think it’s the wiring to the coil pack. The truck runs fine until you get to speeds around 50 to 55 and that’s when you feel the miss fire.
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From: Central NYS
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From what I was told they moved the spark plug wires to a different spark plug and the issue followed. He replaced the fuel injector ...
If you move the coil and plug wire to a new position, and the misfire follows the move, then the coil or plug wire are the bad part... What else can it be......... Make sure the spring inside the rubber boot is stretched out enough so that I makes good contact with the spark plug... and don't put too much elec lube on the boot... ....... also look for cracking of the rubber boot ....... wiped the boot off good to make sure there is nothing on the outside that could be shorting to the sidewall of the hole.
If you move the coil and plug wire to a new position, and the misfire follows the move, then the coil or plug wire are the bad part... What else can it be......... Make sure the spring inside the rubber boot is stretched out enough so that I makes good contact with the spark plug... and don't put too much elec lube on the boot... ....... also look for cracking of the rubber boot ....... wiped the boot off good to make sure there is nothing on the outside that could be shorting to the sidewall of the hole.
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Joined: Sep 2006
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Do we assume you have a 4.6L 97 to 99 model year with plug wires and two coils or a V6 motor with one coil and plug wires?
Why would you/they not see when a trouble follows the parts movement that it is the parts moved is the trouble?
Why would a fuel injector be replaced for a plug wire move?
The computer does ground the coils in the fire order but if a computer of wire harness issue occurs a different code is set. In this case it would be a 354 not 304.
My reply is more for a common sense look at the issue.
A misfire is detected by the computer checking the rotation time of each cylinder and is measured by the front crank sensor.
There is no other way to do this in the system .If the rotation time is to slow compared to all the other cylinders it is called a misfire by the computer..
The 354 code above is an electrical circuit monitor function and not time related..
Sounds like some one is stepping on themselves when trying to solve a simple issue, especially if the trouble moves with a parts move..
Good luck.
Why would you/they not see when a trouble follows the parts movement that it is the parts moved is the trouble?
Why would a fuel injector be replaced for a plug wire move?
The computer does ground the coils in the fire order but if a computer of wire harness issue occurs a different code is set. In this case it would be a 354 not 304.
My reply is more for a common sense look at the issue.
A misfire is detected by the computer checking the rotation time of each cylinder and is measured by the front crank sensor.
There is no other way to do this in the system .If the rotation time is to slow compared to all the other cylinders it is called a misfire by the computer..
The 354 code above is an electrical circuit monitor function and not time related..
Sounds like some one is stepping on themselves when trying to solve a simple issue, especially if the trouble moves with a parts move..
Good luck.
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Rory.jade
1997 - 2006 Expedition & Navigator
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Jan 9, 2015 01:49 AM
