still missing

[Will Freeze]

The engine still has a miss to it....I have changed the plugs....the wires.....cleaned the engine idle thing under the little plastic shroud....checked the vacuum elbow....even taped it to be sure.....still have a sputter and miss to it. Someone said it could be the power pack (coil) how am I supposed to check to see if it has enough umph to make it fire correctly. When I put it on the computer it just says #3 is misfiring....dur! :wacko: I know that!!!! Whats causing it to happen????? What is the next logical part to change out?????? I know that's all they will do at the mechanics shop. change parts until the get the right one. Thanks in advance for suggestions

 

[Gary DiPietroSr]

Any chance of water in your gas?

 

[Will Freeze]

I've been through a number of tanks of gas and also changed out the filter......:wacko:

 

[Nelson Atwell]

Only guessing here...could it be a clogged injector?

 

[Tom Schindler]

Swap plugs from one cylinder to another. See if the problem goes from one cylinder to another. If nothing changes, then swap a wire. That will isolate a problem, if there is one.



My brother had that problem. He has a 1999 Explorer with a 4.0L OHV engine. He had a miss and he thought it was the coil. Doing some research, there is 4 wires going to the coil. 3 hot wires and one ground. So, that thells me that the coil fires two plugs at a time. So, if the coil is bad, in theory you should have a mis-fire in two cylinders.



He He started moving that plug from one to another, and the problem went to the other plug.



He looked closely at the plug and sure enough there was a small crack on the insulation. Replaced the plug and everything is fine.





Tom

 

[Will Freeze]

I changed the plugs to eliminate the plug issue....changed the wires to eliminate the wire issue....I have run multiple bottles of injector cleaner through the engine. I got two codes.....one that the #3 was misfiring and the other was lean mixture???????

 

[Richard L]

micarino,

Injector cleaner will not cure a bad injector, only a dirty injector.



The misfire code on cylinder 3 is an electrical problem The computer can only detect an electrical misfire. If you have replaced the plugs and wires, then you may have a bad coil pack.



The lean mixture error should indicate which bank is running lean via the O2 sensor. It could be a bad 02 sensor, a vaccum leak, or a bad injector as previously stated. You can listen to the injectors with a stethescope or a long screwdriver placed on each injector. You will hear a very audiable clicking sound when the injector is fired. If you hear one that has a softer click it's dirty or bad, and if you don't hear one clicking at all, it's bad and needs to be replaced.



You can try cleaning them but not with the injector cleaner that you add to you gas tank. You need the kind that is in a pressurized can that connects to your fuel rail and you must pull the fuel pump fuse so that the eingine runs only on the fuel & cleaner in the can.



...Rich

 

[Michelle Widell]

I'd check the electrical connector at that injector...

 

[Mike Wilson]

If the above fails, do a compression check and pray that it is not a weak or

broken valve spring on #3 cylinder. :unsure:

 

[Tom Schindler]

micarino said:

I changed the plugs to eliminate the plug issue....changed the wires to eliminate the wire issue....

My brother did too.



So, are you open to suggestions from someone that fixed the problem or do you have your own idea to fix it?



As I said, the coil is the last item I would blame. As I said, the coil has 4 wires going to it. Three wires are for spark and 1 wire is for a ground. Since there are 6 plugs, the coil fires two plugs at the same time. So, if the coil is bad, there should be two misfiring cylinders. Using that reasoning, the coil should not be considered a cause at the moment.



He changed the plugs and a few moths later, he was getting a miss in the exact same cylinder as the old plug was. At first I thought it was from a bad cylinder that was low on compression. When he took my suggestion about swapping the plugs, the problem went to a different cylinder. That is when he knew it was a bad plug.





Tom

 

[Kevin Palmer]

A good shop will not just swap out parts.



My snap-On scanner allows me to hook up the scanner. Run the engine. Note the RPM's. Knock out one injector at a time and not the RPM's. If you knock out an injector and the RPM's drop then you know the injector is good.



If you knock it out and there are no RPM difference then the injector is either defective or there is an issue with the cylinder itself, (valve or rings). This is based on the fact that you are certain you have a good base engine, (good wires, plugs and fuel).



So go to a shop and see what their capabilities are. Get a price to do a cylinder drop test, then go from there..

 

[TomT]

My wife's Expedition recently had a similar problem. They kept replacing the coils and it would run fine for a while then back to missing. Finally they traced the problem back to a ground short in the computer. Replaced the computer and now every things fine. If it is the computer, DON'T buy one from Ford. They want $400 for a new one. My mechanic found an aftermarket one for $150 that he claims is just as good if not better.