I'm currently struggling to get my truck running well. 1995 f150 4.9 I6. 5 speed m50dr2 tranny 4x4.
I did a complete tune up, spark plugs, wires, (motorcraft brand ) fuel filter, oil filter I even installed a new durlast gold distributor and Its still running rough.. someone told me about cleaning the MAF sensor.. looking to every open idea their is. Much appreciated.

 

Hi Tallguy ,

Can we ask if the misfire was there before you replaced a lot of parts?

If it was, maybe you can isolate it to the one cylinder ,,,,, if it is coming from only one cyl.

Carefully remove the plugs from each injector , one at a time, when it is idling and look for the cyl that made little or no difference when the injector was disabled.
It is not wise to remove a spark plug wire from the plugs to do this because that can destroy an ignition module since the spark has no place to go and that spike finds a way within the module, so not recommended, OK ?

Since the MAF affects all the cyls, I would not go after that yet. Let's see what you find and we can go from there.

 

[QUOTE=hanky;114088]Hi Tallguy ,

Can we ask if the misfire was there before you replaced a lot of parts?

Hanky, yes it did misfire before I replaced everything. I do remember my buddy testing the compression I believe in 2 cylinders the compression was lower then it should be.. maybe like 90 psi. I have not gotten a chance to undo the spark plugs from the injectors yet.. it did run a little better after the tune up. But still misfiring real bad. When I check the plugs at the injectors would I unplug them at the distributor cap or where the spark plugs go into the head?

 

The fuel injectors and the spark plugs are two completely different things.

Each cyl does, however, have a fuel injector and a spark plug ,,,,right ?

We will not do anything related to the spark plugs yet..

There is a tubular rail that supplies fuel to the 6 injectors. Each of those injectors has 2 wires connected to them. They are contained in a plug that plugs onto the injector.

That plug is what you would remove to prevent the injector from injecting fuel into the cyl. With no fuel to ignite the cyl will not fire and do it's share of the work.
If the engine is misfiring, that means a cyl is not doing it's share of the work. When we disable an injector , that cyl will misfire and that is what we are looking for.
If you disable a cyl where everything is working correctly , you will definitely notice a difference in engine RPM.when you disable the injector.
So, if we disable an injector for a cyl that is not working you will not notice any difference in RPM.

That is the cyl with the problem. Let's see if we can do this OK ?

 

Hanky, wow definitely a rookie move. I'm somewhat mechanically inclined my pops died when I was a young age so only had my mom to raise me. I teach myself and try to learn as much as possible. I can definitely do that and will get back to you with feed back. Just gotta wait for this rain ti stop. Gotta love PA.
I appreciate you taking your time to tell me in such detail .

 

You can do this.
There are a lot good instructional videos on U tube. There are some others too. Anyone can put out a video and some as you will learn are not everything they should be.
The more you learn , you eventually will be able to see the difference.

I believe this forum is a good place to learn and share what you have learned.

There are a lot of knowledgeable folks here and they are always willing to help.

 

Just real quick I went out and messed with it. Going out to eat with the old lady couldn't mess with it long. Starting from the first injector closest to the front. Then the second... it was actually loose. The actually injector where you told me to unplug that wire.. it Is loose as could be..not the plug. The injector. Stopped at it right there was getting yelled at.

 

After a good meal, maybe you might find time to read some more. The injectors have O rings on them and when placed in the engine are not supposed to allow any additional air to enter because that could cause a misfire, too much air is almost like the injector not injecting sufficient fuel. The fuel rail that the tops of the injectors are placed in is what retains the injectors in place If there is a problem with the O ring for that injector where it goes into the engine, you might have found the problem. We don't know for sure yet , but after checking as suggested you might find that when you unplug that loose injector if there is no change in engine RPM it is now suspect.

 

Hanky, I'm gonna go out and unplug the injectors 1 by 1 and see if I see a difference. I was reading a couple things. Someone said that there injectors spin freely. I also read if they are spinning freely the o ring may be dry and causing it to spin.. so I'm probably pointing towards new injectors?

 

The first and second injectors are actually loose. The 3rd one back is tight. Should they be this loose? Injectors look terrible too