Staggered Ignition, what the hell? - Hemi Truck Club
 
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Old 04-18-2012, 08:35 PM  
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After doing some research and reading some of the other threads about shorty wires vs long wires I have a better understanding of what's going on now. I always thought the second plug fired a millisecond after the primary plug for more complete combustion, but not so. I looked at the setup on my truck and this is what I found, the coil of course fires the primary plug on it's respective cylinder but the secondary terminal fires the secondary plug on a cylinder halfway through the firing order. In other words, 1 fires 6, 8-5, 4-7, 3-2, 6-1, 5-8, 7-4 and 2-3. It's like Superjay said, that second plug fires at the end of the exhaust stroke and what good could it do?

Anyways, I decided to stay with the long wires. Living here in the Republik of Kalifornia it would probably fail the visual emissions inspection with the shorties.

That got me thinking though. A while back someone posted about blowing up their intake plenum while doing the seafoam treatment. I just wonder if there might have been a little build up of seafoam and that second plug fired causing a delayed igniton and the thing fired off just as the intake was opening, just a theory.

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Old 04-18-2012, 08:35 PM  
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After doing some research and reading some of the other threads about shorty wires vs long wires I have a better understanding of what's going on now. I always thought the second plug fired a millisecond after the primary plug for more complete combustion, but not so. I looked at the setup on my truck and this is what I found, the coil of course fires the primary plug on it's respective cylinder but the secondary terminal fires the secondary plug on a cylinder halfway through the firing order. In other words, 1 fires 6, 8-5, 4-7, 3-2, 6-1, 5-8, 7-4 and 2-3. It's like Superjay said, that second plug fires at the end of the exhaust stroke and what good could it do?

Anyways, I decided to stay with the long wires. Living here in the Republik of Kalifornia it would probably fail the visual emissions inspection with the shorties.

That got me thinking though. A while back someone posted about blowing up their intake plenum while doing the seafoam treatment. I just wonder if there might have been a little build up of seafoam and that second plug fired causing a delayed igniton and the thing fired off just as the intake was opening, just a theory.
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Old 04-18-2012, 09:39 PM  
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What good it does is it allows each coil to fire one plug under compression and one not. Shorties require each coil to fire both its plugs under compression. Those long wires allowed Dodge to get by with somewhat smaller coils.
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Old 04-19-2012, 02:01 PM  
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Waste spark theories run amuck, my thought is anytime high tension wires can be eliminated the less you have to go wrong.
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Old 04-19-2012, 02:27 PM  
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Has anyone here ever just pulled the second wire off and see how it runs?
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Old 04-19-2012, 03:43 PM  
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This is great fun, but to take the mystery out of it here is the description from the manual.

EXAMPLE : When the #1 cylinder is on compression
stroke and ready for spark, the #1 coil will fire one of the dual spark plugs on the #1 cylinder (directly below the coil). The other dual spark plug on the #1 cylinder will be fired by the #6 coil. At the same time, the #1 coil will fire a “wasted spark” to one of the dual spark plugs at the #6 cylinder as coil #6 also fires a “wasted spark” to one of the dual spark plugs at the #6 cylinder.

The thing to keep in mind is that the paired cylinder (waste spark) is being triggered by the PCM. So when the coils are converted to the newer 6.1 style or shorties are installed the the paired cylinder is still being fired by the PCM. Good luck
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Old 04-19-2012, 09:22 PM  
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...to answer the previous question,I passed California smog in 2010 with the shorty wires installed....Comp 260 cam...JBA mid headers....with the stock airbox on.....let's see if I can do it again this december...?
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Old 04-19-2012, 09:25 PM  
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Quote:
The thing to keep in mind is that the paired cylinder (waste spark) is being triggered by the PCM. So when the coils are converted to the newer 6.1 style or shorties are installed the the paired cylinder is still being fired by the PCM. Good luck
Now that's truly wasted spark! I was thinking about this situation also, but I guess other than the wasted alternator energy, it's not really hurting anything.
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New Blue: 2005 1500 4X4 SLT Standard Cab Longbox 5.7 Hemi

MSD 8.5 Super Conductor wires, Airaid CAI, Superchips 3865,
Homebrew E-fan, Custom 2.5" Dual Exhaust with merge Y & 22"
Magnaflow SIDO, Sonnax pressure booster, Stant 190 stat, Fastman TB
---------------------------------------------------------------------------------------
Old Blue: 1988 W100 4X4 Standard Cab Longbox 318 188,000 miles
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Old 04-19-2012, 11:16 PM  
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To me a lot of the explanations cover the functions of the wires (long and short) without mentioning the reason it was done in the first place. This is from Dodge Forum:
Quote:
A waste spark system is when in the spark plugs fire in pairs, on both the exhaust and compression strokes. The extra spark on the exhaust stroke has little effect and is thus "wasted". Actually a "wasted spark" is not wasted. This method of firing multiple spark plugs was implemented by many manufacturers as a way to reduce exhaust gas emissions and production costs. It reduces production costs by requiring less coil packs. For example: a V-6 engine would only need three coil packs instead of six, this is because an idividual coil fires two spark plugs at one time, one spark plug on a compression stroke (which is where the power comes from) and one spark plug in another cylender on an exhaust stroke, simultaniously. This method of "double firing" also reduces exhaust gas emissions because the spark plug that is fired during the exhaust stroke burns (or cleans up) remaining fuel left over from the previous combustion stroke before it has a chance to exit the engine through the tail pipe.
http://dodgeforum.com/forum/3r...ires-for-hemi-2.html
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Old 04-20-2012, 04:49 AM  
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Oh the "why".. I believe Dave has the answer with it being part of the emissions stradegy. Several manufactures used spark plugs to burn exhaust gases and I remember reading Honda lead the way in doing that. MSD has a timing controller that allows you to eliminate the waste spark.
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Current 1/4 mile [email protected] (2018)
Current 60' PB 1.351 (2019) mechanical issue for 1/4m

HTC 2018 TOTY

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