Spark plug change interval

That black plug defiantly wasn’t doing its part .. but must have been some firing for 50000 miles till it decide to cause the codes and slight misfire ... I must have deleted the other 3 plugs pic without knowing it somehow someway .. I took the pic of both left and right bank plugs in the proper order . then a comparison pic with the bad one ...

rottenronnie said:

I wasn't aware the Gen III used a wasted-spark system. To have a plug fire on the exhaust-stroke in an attempt to reduce emissions apparently works.

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It's pretty easy to tell actually, 2 coil packs, 3 coils in one, 2 coils in the other with a total of 5 trigger wires. Not only is it cheaper to implement but it did help with emissions.

I apologize for the not so great scan, the FSM is kind of big and tough to hold on my not so big scanner. Lower right side of the image tells the tail.

Same part number as the 4 and 6 cylinder dodge minivans.

Might as well save money where you can.

No info about the wasted spark system, that I could find for the Gen III though

I'd like to read about that.

beastmode1 said:

D

Did you have to gap them and what gap specs?

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I Don't believe you have to gap them.

thewelshm

rottenronnie said:

No info about the wasted spark system, that I could find for the Gen III though

I'd like to read about that.

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See the image above your post, bottom right. If you have 1 coil that fires 2 plugs in a 4 cycle engine and those cylinders are not on the compression stroke at the same time, and they are not, it is a wasted spark system.

I read about the emissions part in one of the FSM's for either the truck or a Viper. If I run across it I'll pass along the reference.

Yes, thanks, I have the service manual but it doesn't go into wasted spark detail like I was hoping.

As long as the ecu is timed to fire the plugs on the proper cylinders' compression stroke and the other cylinders' exhaust.

rottenronnie said:

As long as the ecu is timed to fire the plugs on the proper cylinders' compression stroke and the other cylinders' exhaust.

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PCM doesn't really have to. It's purely mechanical. The same coil fires 2 plugs. Those cylinders are opposite each other via cam timing and at the same point via crank journals. So if all you did was run timing for 1 cylinder you would be running it for 2. That is exactly what they do :

In fact take a look at the backside of this 2004 flywheel. It's easier to see on an 04 because it's before they moved the crank trigger to a wheel on the crank.

Notice there are just 5 distinct trigger blocks [ the little ones ].

Interesting...

THEWELSHM said:

I Don't believe you have to gap them.

thewelshm

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Thanks for the heads up.

This thread came up at just the right time; it prompted me to finally change my spark plugs at 78,000+ miles. Truck has been running great but I had some time off. Went with the Champions ultimately. The pics show the old plugs c/t the new ones. The other pics shows all the old plugs with the plugs on the left side coming from the passenger side and the plugs on the right side are from the drivers side. The plugs at the bottom of the pic represent the front of the truck and they are in the same order as the cylinders. Cylinder #1 (bottom right) looked the worst and had a very small amount of oil on it and there was a small amount on the block (shown in a different photo). I included some up close photos too. The gaps ranged from 0.45 -0.50. Anything I should be worried about?

Good time to change them. Good colour ....same as mine. Oil is most likely weeping rocker cover gasket. Sounds like a fairly common occurrence.

They look pretty normal for the stock cylinder heads.
Oil on the outside, yup, check your valve cover seal.

Don't worry, just change them a little more often.

rottenronnie said:

Don't worry, just change them a little more often.

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Question. Should the coils and wires be changed at the same time, or do they normally last longer than a set of plugs?

I have never changed the coils.
I have changed the wires a few times but I've also taken my engine apart "way more than normal" so they are subject to twisting and pulling.
Plugs are changed more often than coils and wires.

New plugs in truck when head gaskets done. I pulled them today and opened gap from 35 thou to 55 thou. DUI recommend the gap 60 to 65 for the Screamin' Demon Coils but even 55 is getting ugly. Need a longer earth strap. There is only so much you can do to make the strap look like it should. I have NGK ZFR5N plugs and they are all same same and clean as a whistle.
I was going to index the plugs (I think that is what it is called) but as you can only see the first 2 on each side that was a waste of time.
Plug #9 is character building, na it's just a shit. Easier to pull the motor out to change it and while at it change the thermostat as well.
The stories I have read say the OEM coils are weak after 4000rpm. DUI reckon the Screamin' Demon Coils and Live Wires make a difference that can be measured on the Dyno. We will see soon enough. Once my underdrive pulley turns up I can add another 50hp. That should be ....with all the go fast bits.... and shiny stickers....about 15000hp or close to it. Hope to be dyno in next couple of weeks.
I do like the wasted spark system the exhaust crackles away at low revs on de-acceleration. My favourite

I just put in a set of E3's with the demon coils. I will check them and take pictures of them every couple thousand miles if anybody thinks that would help.