I've got this problem with cylinder 4 spark plugs...

[shane96ranger]

Hey guys, there's really not an ignition section to speak of, so I'll ask in here. I have now lost firing in cylinder 4 three times now (it was like that when I bought it and it's happened twice since - every 6 or 7 months). Every time the fix has been to replace the spark plug. The plug has normal wear and the truck runs fantastic otherwise.

They told me at Autozone it was because I am running the Autolite Platinums, and I should be running the Motorcraft Finewire's. That's what I've switched to, but I'm not convinced that is my issue. I've also replaced the wires in the middle of all of this, so it's happened with 2 sets of wires.

So, my question is...... does the coil pack have an individual coil for each cylinder? This is my only logical guess I can think of. Are there any other factors I should look into?

Thanks!

 

[shane96ranger]

Nobody???

 

[adsm08]

You have what is known as a "waste spark" system. You have 3 coils. Each coil is matched to 2 cylinders. Each time the coil fires, both plugs spark. One at the top of the compression/power stroke, the other is on it's exhaust stroke. If you lay out your firing order, cut it in half and set the second half under the first, that is your pairing. For example1-4-2-5-3-6 goes to:

1-4-2
5-3-6

for your truck.


The design of the coil pack allows one cylinder on the coil to misfire due to a coil issue while the other side stays functioning properly. This is actually a great diagnostic aid if the tools are available to view the power-balance graph.

When you replace your plug, switch the #3 and #4 wires at the coil end and run it for a while. If, this issue starts up again but the misfire is on cylinder 3 this time, your coil is probably burning the plugs up.

 

[shane96ranger]

You have what is known as a "waste spark" system. You have 3 coils. Each coil is matched to 2 cylinders. Each time the coil fires, both plugs spark. One at the top of the compression/power stroke, the other is on it's exhaust stroke. If you lay out your firing order, cut it in half and set the second half under the first, that is your pairing. For example1-4-2-5-3-6 goes to:

1-4-2
5-3-6

for your truck.


The design of the coil pack allows one cylinder on the coil to misfire due to a coil issue while the other side stays functioning properly. This is actually a great diagnostic aid if the tools are available to view the power-balance graph.

When you replace your plug, switch the #3 and #4 wires at the coil end and run it for a while. If, this issue starts up again but the misfire is on cylinder 3 this time, your coil is probably burning the plugs up.

Thanks a ton man! I will give this a try. The coil burning out the plug is the only logical explanation I can think of, and from your info it sounds plausible. By the way, I tried to give you some rep, but since I recently gave you rep it won't let me do it again.

 

[danielwd]

Hey guys, there's really not an ignition section to speak of, so I'll ask in here. I have now lost firing in cylinder 4 three times now (it was like that when I bought it and it's happened twice since - every 6 or 7 months). Every time the fix has been to replace the spark plug. The plug has normal wear and the truck runs fantastic otherwise.

I'm simply curious - how do you konw you lost the spark in cylinder 4?

 

[shane96ranger]

I'm simply curious - how do you konw you lost the spark in cylinder 4?

My scanner gave me the code for cylinder 4 misfire. This could mean one of 4 things. Spark plug, plug wire, ignition coil, or fuel injector. The plug did not look lean or rich, so to me that rules out injector. So I started simple with the plug (my wires are new), and also because this is exactly the same scenario I went through 6 months ago. It runs great again.

 

[danielwd]

My scanner gave me the code for cylinder 4 misfire. This could mean one of 4 things. Spark plug, plug wire, ignition coil, or fuel injector. The plug did not look lean or rich, so to me that rules out injector. So I started simple with the plug (my wires are new), and also because this is exactly the same scenario I went through 6 months ago. It runs great again.

So if I had clogged fuel injectors, I could visually expect to see a problem with the spark plugs?

 

[shane96ranger]

So if I had clogged fuel injectors, I could visually expect to see a problem with the spark plugs?

A lean condition in a cylinder would make the plug turn white most likely, or even cause the tip to melt. Normal wear will be light brown in color. Here's a pretty good guide for you to look at:

http://www.superstreetonline.com/techarticles/130_0703_reading_spark_plugs/photo_03.html

 

[danielwd]

A lean condition in a cylinder would make the plug turn white most likely, or even cause the tip to melt. Normal wear will be light brown in color. Here's a pretty good guide for you to look at:

http://www.superstreetonline.com/techarticles/130_0703_reading_spark_plugs/photo_03.html

I like # 11, it made me laugh when the caption basically implies that you are screwed!

 

[adsm08]

Well, the last time I saw a plug that looked like #11, I ended up putting a whole engine in the car. So yeah, pretty screwed.

 

[shane96ranger]

I like # 11, it made me laugh when the caption basically implies that you are screwed!

Yeah, you're royally screwed there, LOL. Like adsm08 said, you're looking at a new motor.

 

[TheTopher]

Well, the last time I saw a plug that looked like #11, I ended up putting a whole engine in the car. So yeah, pretty screwed.

I'm gonna go F#&@# up the plugs in my company truck and see if I can talk them into making the new motor be a v8.


...on second thought they'll probably just give me one of the older more beat up trucks to drive instead. I'd better not do that.

 

[shane96ranger]

I'm gonna go F#&@# up the plugs in my company truck and see if I can talk them into making the new motor be a v8.


...on second thought they'll probably just give me one of the older more beat up trucks to drive instead. I'd better not do that.

Damned if you do, damned if you don't.

 

[TheTopher]

Damned if you do, damned if you don't.

But only because our work trucks are chevies.

 

[adsm08]

I'm gonna go F#&@# up the plugs in my company truck and see if I can talk them into making the new motor be a v8.


...on second thought they'll probably just give me one of the older more beat up trucks to drive instead. I'd better not do that.

Well, if you recall that particular carnage thread it also had a shattered piston, two broken off valves, another that I never found, a few holes in the block....