Newbie Spark plug replace questions
#11
12-08-2006, 12:48 PM
RE: Newbie Spark plug replace questions
So as a follow on question, how does putting copper plugs into this system affect the efficiency of the spark and performance?
I pulled the plugs yesterday and replaced the originals and I do believe they are origianl plugs as there is 59K on the car (one of which was VERY corroded on the tip. with copper plugs. I believe the ones I pulled were Platinums as
1. the delco replace part for the car were platinums and
2. the plugs I pulled had an extra tit on the end of the ground tip (center ground elctrode?)
I'd like to get ahold of the 'engineer' that designed where the plugs fit up under the exhaust manifold. Three I got out from up top, three I had to go under the car to get to, And number 6 I had to put an open end wrengh on the end of the socket cuz there was no way to get the socket extension past the manifold and other crap to get a straight line on the plug (that was under the car). 3 hours to change 6 plugs. And I thought my Jag XJS V-12 was a pain in the a$$.....
The car is pulling noticably harder now as a quick check of the other 5 plus showed typical wear showing the need for replacements...
I pulled the plugs yesterday and replaced the originals and I do believe they are origianl plugs as there is 59K on the car (one of which was VERY corroded on the tip. with copper plugs. I believe the ones I pulled were Platinums as
1. the delco replace part for the car were platinums and
2. the plugs I pulled had an extra tit on the end of the ground tip (center ground elctrode?)
I'd like to get ahold of the 'engineer' that designed where the plugs fit up under the exhaust manifold. Three I got out from up top, three I had to go under the car to get to, And number 6 I had to put an open end wrengh on the end of the socket cuz there was no way to get the socket extension past the manifold and other crap to get a straight line on the plug (that was under the car). 3 hours to change 6 plugs. And I thought my Jag XJS V-12 was a pain in the a$$.....
The car is pulling noticably harder now as a quick check of the other 5 plus showed typical wear showing the need for replacements...
#12
12-08-2006, 01:57 PM
RE: Newbie Spark plug replace questions
I understand that electrons flow one way. But if you notice the ground electrode, it is grounded to the block. So if you have a tower that releases a negative charge down the spark plug wire to a spark plug that has a negative ground, how does that work. It's not like that two posts has two wires to 1 spark plug.
"Because both ends of the coil fire a spark at the same time, one coil tower has to fires a positive spark, while the other tower has to fire a negative spark." So you're telling me that that coil when the crank rotates 180 degrees, that the coil then has to change polarities?
"Because both ends of the coil fire a spark at the same time, one coil tower has to fires a positive spark, while the other tower has to fire a negative spark." So you're telling me that that coil when the crank rotates 180 degrees, that the coil then has to change polarities?
ORIGINAL: z28pete
These coils have two towers and fire two plugs at one time, one plug is fired on the compression stroke of one cylinder while the other is fired during the exhaust stroke of a mated cylinder and accomplishes nothing (waste spark). Because both ends of the coil fire a spark at the same time, one coil tower has to fires a positive spark, while the other tower has to fire a negative spark. Because elctrons can only flow in one direction, negative to positive, and a spark is pure electron flow, one of the plugs will fire from the center electrode to ground, while the other one will fire from the ground electrode to the center electrode. The electrode initiating the spark will loose more material and erode faster compared to the one receiving the spark. To make things a little more confusing, most schematics use the conventional way to show current flow, wich is from positive to negative, but it the opposite of what really happens. However, for most practical purposes it really makes no difference which system you use as long as you are consistent.
ORIGINAL: shnormo
I'm just dumbfounded how this works. If the spark plug is getting grounded to the block, how is it possible to have a center ground electrode?
I'm just dumbfounded how this works. If the spark plug is getting grounded to the block, how is it possible to have a center ground electrode?
ORIGINAL: z28pete
If you are misfiring on just one cylinder the coils are good. Probably a bad plug or wire. Whichever plugs you choose, keep in mind that with the DIS ignition system, 3 plugs fire from the center electrode to the ground electrode, and he other 3 fire backwards from ground electrode to center electrode, which means that if you use platinum or irridium plugs both the ground and the center electrode need to be tipped, otherwise 3 of the plugs will wear out fairly quickly while the other 3 will go for the life of the car.
If you are misfiring on just one cylinder the coils are good. Probably a bad plug or wire. Whichever plugs you choose, keep in mind that with the DIS ignition system, 3 plugs fire from the center electrode to the ground electrode, and he other 3 fire backwards from ground electrode to center electrode, which means that if you use platinum or irridium plugs both the ground and the center electrode need to be tipped, otherwise 3 of the plugs will wear out fairly quickly while the other 3 will go for the life of the car.
#13
12-08-2006, 04:25 PM
RE: Newbie Spark plug replace questions
The positive and negative sparks are in relation to ground. So when the coil is fired, by the law of phisycs, one end of the secondary winding has to be positive and the other end has to be negative, and the midpoint has no voltage.
Assuming the coil is rated at 30,000 volt. The positive spark will be 30,000 volt more positive than ground , while the negative spark will be 30,000 volt more negative than ground, but the voltage between the 2 towers will be 60,000 Volt.
Think of 220 Volt AC coming into your house. It comes from the power transformer (just a huge coil) on 3 wires, 2 hot wires and a neutral wire strapped to ground. The 2 hot wires are in opposite polarity to each other. Because this is AC when one wire goes negative the other goes positive. The voltage between each hot wire to ground is 110 volt, but the voltage between the 2 hot wires is always 220 volts.
Norm, try this link and see section on distributorless ignition. Figures 5 & 6
http://www.procarcare.com/icarumba/r...a_ignition.asp
Assuming the coil is rated at 30,000 volt. The positive spark will be 30,000 volt more positive than ground , while the negative spark will be 30,000 volt more negative than ground, but the voltage between the 2 towers will be 60,000 Volt.
Think of 220 Volt AC coming into your house. It comes from the power transformer (just a huge coil) on 3 wires, 2 hot wires and a neutral wire strapped to ground. The 2 hot wires are in opposite polarity to each other. Because this is AC when one wire goes negative the other goes positive. The voltage between each hot wire to ground is 110 volt, but the voltage between the 2 hot wires is always 220 volts.
Norm, try this link and see section on distributorless ignition. Figures 5 & 6
http://www.procarcare.com/icarumba/r...a_ignition.asp
#14
12-08-2006, 04:40 PM
RE: Newbie Spark plug replace questions
I had the worst time changing the plugs on my 3.4 a few months ago....they make them so hard to get at! Especially the back ones. I'd recommend making sure you have all the extensions possible for the different spots they threw em in.
#16
12-09-2006, 05:31 PM
RE: Newbie Spark plug replace questions
Ok guys we're getting a bit confused with the wasted spark concept. This type of ignition was on my '48 HD sidevalve as well as every 180 degree twin or 4 cyl motorcycle I've ever seen. It's been around for a while.
As was explained to me by a VERY respected Suzuki MC tech rep: Only 1 lead produces a spark, the one with the least resistance. Since the mixture in the 'firing' cylinder is more conductive (because of the compressed air fuel mix) then the extremely lean (exhaust cylinder with no fuel mix) the spark will always occure in the proper cylinder.
That's it, nothing fancy. Just electricty doing what comes naturally.
Oh, and by the way, ALL spark plug center electrodes are alloyed with copper. That was just a Champion sales blurb.
As was explained to me by a VERY respected Suzuki MC tech rep: Only 1 lead produces a spark, the one with the least resistance. Since the mixture in the 'firing' cylinder is more conductive (because of the compressed air fuel mix) then the extremely lean (exhaust cylinder with no fuel mix) the spark will always occure in the proper cylinder.
That's it, nothing fancy. Just electricty doing what comes naturally.
Oh, and by the way, ALL spark plug center electrodes are alloyed with copper. That was just a Champion sales blurb.
#17
12-09-2006, 06:26 PM
RE: Newbie Spark plug replace questions
Meaning no disrespect, but your friend may be a very good mechanic, but not too good on electronics. I suggest you connect a dual trace oscilloscope probes to both ends of the same coil and observe the trace when the engine runs.
This ad from autolite may convince you.
http://www.autolitesparkplugs.com/sp...?kw=DIS&mfid=5
This ad from autolite may convince you.
http://www.autolitesparkplugs.com/sp...?kw=DIS&mfid=5
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