double platinum plugs

[Donald]

A knowledgeable mechanic was telling me that for cars where they have 1 coil per 2 cylinders that they need double platinum plugs as what wears is where the spark jumps from and its hard for consumers to figure this out so they use double platinum. He said when Ford made cars like this, they would install basically 3 right hand plugs and 3 left hand plugs, but did not sell these type of plugs as no one would get it right.

So for cars where there is one coil per 2 plugs, they must give a spark for one at power and the other at exhaust. Are these plugs in series or parallel? His explanation does not make sense unless in series (I think).

 

[Quest]

this is called "waste spark" systems where spark jumps from 1 plugs to another to complete it's route.

Sparking are done in series and his explanation is indeed correct (there's no such thing called paralleling spark plugs)

Q.

 

[alanu]

For example a v6 may have 3 coil packs. 2 spark plug leads to 1 coil pack. The ECU will send a negative signal to 1 coil pack at a time to fire the coil. As each coil fires one will fire on the compression and the other on the exhaust stroke. I recall little improvements on emissions output with a "waste spark" system. It was introduced in the 80's.

Yes essentially a 30,000km spark plug has 60,000Km on it.

I've seen little wear on waste spark systems using cheaper lines of platinums. For example the GPower NGK's hold up well and the grounding electrode doesn't wear no wear as quickly as a typical traditional plug.

Maybe ford should address the snapping broken siezed spark plugs in the newer f150 tritons or logically/strategically place plugs where it doesn't take hours to change plugs. Double platinum wouldn't be required if plugs are easily accessible. The longer a plug stays in an aluminum head the higher chances of siezing. Look at a "new" style plug in those trucks and you'll wonder why they are trying to reinvent the wheel. Many nissan products are no better.

oh ohhhhh here I start ranting..........

 

[Axe Man]

I am very familiar with the waste spark system used on the 1995 - 2002 Kia Sportage. This engine was a variant of the Mazda FE DOHC 2.0 liter inline 4. In this system there was a coil pack over cylinder 4 with a plug wire to cylinder 1. Another coil pack over cylinder 2 with a plug wire to cylinder 3. The factory plugs were NGK resistor plugs with a change interval of 30K miles. They did show some erosion after 30K but not excessive.

This system was very forgiving as far as plug type was concerned. You could use single plats, +2 plats, or even +4 plats with no problems.

If you study the electrical schematic for the coil outputs it does appear to be a series arrangement. But you could have the a joining plug wire open up and cause a misfire on that cylinder but the other cylinder in the pair(with the coil pack) would still fire.

 

[parimento1]

Last changed my plugs at 60k miles plugs looked new. Checked them now at 130k miles they still look brand new. I dont know if the Toyota plugs are 100k mile plugs, but I think they can go at least that by the way they were wearing; or lack thereof.

 

[mechtech2]

Donald - Right. A waste spark system fires 2 plugs at once. Just like motorcycles have been doing for decades.
One plug erodes the center electrode [like a normal ignition], and the other erodes the side ground electrode.
So to save precious platinum, the manufacturers use platinum only on the tip that is needed. The replacement plugs often have 2 plat tips to avoid putting them in the wrong hole.

 

[Whimsey]

Originally Posted By: mechtech2
Donald - Right. A waste spark system fires 2 plugs at once. Just like motorcycles have been doing for decades.
One plug erodes the center electrode [like a normal ignition], and the other erodes the side ground electrode.
So to save precious platinum, the manufacturers use platinum only on the tip that is needed. The replacement plugs often have 2 plat tips to avoid putting them in the wrong hole.


Yepper, my 1996 Ford Contour, with the 4 cyl Zetec from the factory used Motorcraft plugs with platinum discs on only one of the electrodes for the four plugs. Two had them on center electrode and two on the side electrode. My Motorcraft replacement plugs have them on both electrodes. I guess it's "Spark Plug Installation For Dummies". I guess Ford figures better save than sorry when changing these plugs. I have no complaints. After 25,000 miles they still run great and my mpg is the same as when I put them in.

Whimsey

 

[oilyriser]

My car will erode the Pt wire of an NGK single in 75000 km, leaving the other one in the pair in very good condition. I might rotate plugs at 50000 this time, and get a total of 100k out of them.

 

[severach]

No need to move the plugs. Just swap the wires.

 

[oilyriser]

Hey, you're right. A couple of neon lights held against the wires while the engine idles should let me see which wires fire at the same time.

 

[Paul56]

Originally Posted By: alanu
The longer a plug stays in an aluminum head the higher chances of siezing.


Even when the threads are coated with anti-seize on install?

 

[Propflux01]

Yes.

 

[03cvpi]

Most Ford Escorts use two different kinds of plugs, I believe 1 and 3 are copper electrode and 2 and 4 are platinum, electrode. They usually have a color coded tip, white for platinum and orange for copper. Single coilpack divided into two circuits, to fire two plug at a time. I just changed mine out on a 97 escort with 30k on the clock. Although the plugs looked good enough to just clean and reinstall, I opted for replacing with single platinums. AT 2.00 each for single platinums versus 4.50 each for double platinum and ten minutes to change, I'll go the cheap route. Plus the spark plugs should be atleast removed and recoated with anti-sieze about every 30 to 40k to keep them from freezing in the hole. Especially on the 5.4L modular, the 4.6L has had the blowout problem, but not to the extent that the 5.4 has. Also do not over tighten. I use a torque wrench and never exceed the 11-13fp. I did notice the idle improved a bit when sitting at a light with my foot on the brake.

 

[oilyriser]

If the coil driver were an H bridge circuit, the spark polarity could be reversed every other spark to equalize wear on all the plugs. This would allow them to use cheap plugs all around.

I'm just gonna use an ohmmeter to see which terminals on the coil pack are part of the same coil, and swap the wires after 40,000 km. Changing plugs on my car is a scratch and bruise job.

 

[severach]

With my car you just swap the two wires that are clearly the same coil. You also get a clear indication whether or not you are on the first or second round. On the second round the wires will be on the wrong number of the right coil.

I've considered doing this but the plugs aren't very expensive, 60,000 miles doesn't come very often, you must do it before the fast wearing electrode wears out completely, and at that age the plugs look pretty bedraggled and often show leakage lines. Pulling them out to refresh the threads and anti seize seems like a good idea.

You don't need neon lights either. Cylinder pairs are not picked randomly. Just count ahead in the firing order.

 

[SHOZ]

Ford's waste spark fires one plug from the electrode to the block, the opposite plug from the block to the electrode. From the factory the block to electrode plugs were single plats, the electrode to block ones were double plats. It's all moot now with the newer Fine Wire plugs they use.

 

[Lumberg]

Originally Posted By: oilyriser
. Changing plugs on my car is a scratch and bruise job.

Oh man I know what you mean. I used to have a V6 Camry. The factory manual had you removing the intake manifold to change the rear bank of plugs. Creative use of extensions & swivels allowed me to do it w/0 removing the intake, but it was a scratch, bruise, curse, and sweat job!