4.6DOHC firing order ??????

[kstones63]

My 4.6 DOHC engine from the Mark VIII that is going into my truck has the coil packs on the front of the engine. I am switching it over to the coil over plug design. I found a guy on another website that makes a harness to plug into mine and then plugs into the COP's. When I got the harness I noticed that the plugs for each coil pack only has 3 wires going to each bank of the engine. My original coil packs are the same. One wire is the ground and the other 2 are for the coil drivers from the computer.
After doing some more research, I found that the computer only has 4 drivers for all 8 cylinders, so this tells me that 2 plugs are firing at the same time.????
Does anybody know if this fires one cylinder on the left and one cylinder on the right at the same time or does it fire one on the compression stroke and one on the exhaust stroke to keep emissions down? This seems like it would backfire out the exhaust. This engine does not have a smog pump on it from the factory.
I haven't checked the cam timing yet to see if 2 cylinders are on compression stroke at the same time. Both orignal coil packs have 2 wires that go to the left bank and 2 go to the right.
There are only 6 wires that run all 8 COP and 2 of those are grounds.
Any ideas????????????????????????????????????????????????????

Kevin

[don morris II]

it fires one on the compression and one on the exhaust my 98 f150 with the 4.2 fires this way hope this helps
it fires every time the piston comes up

[DIXONBOY]

Don's right. I work at a Ford dealer. They have what they call a wasted spark. I belive one fires on the compresion and on on the exaust. Im in parts now and was a tech but its been about 5 years. I'll try to find the info. on it.

[DIXONBOY]

Coil Pack
A coil in a coil pack is turned on (i.e. coil charging) by the PCM, then turned off firing two spark plugs at once. The spark plugs are paired so that as one spark plug fires on the compression stroke, the other spark plug fires on the exhaust stroke. The next time the coil is fired the order is reversed. The next pair of spark plugs fire according to the engine firing order.

The Coil On Plug works in the same manner as a standard coil pack. Since each cylinder has its own coil, only one spark plug is fired at a time and only on the compression stroke.

If you need anything else like wire diagrams let me know.




Figure 57: Six-Tower Coil Pack

[kstones63]

Coil Pack
A coil in a coil pack is turned on (i.e. coil charging) by the PCM, then turned off firing two spark plugs at once. The spark plugs are paired so that as one spark plug fires on the compression stroke, the other spark plug fires on the exhaust stroke. The next time the coil is fired the order is reversed. The next pair of spark plugs fire according to the engine firing order.

The Coil On Plug works in the same manner as a standard coil pack. Since each cylinder has its own coil, only one spark plug is fired at a time and only on the compression stroke.

If you need anything else like wire diagrams let me know.




Figure 57: Six-Tower Coil Pack

Thank you everybody for the help. It just helps me understand how this all works.
My COP will still work like the coil pack because it is a conversion and the harness is set up to fire the 2 at the same time. I assume that it must be to help with emissions?
I have not had the cam covers off yet to check the cam positioning. That was my next step to get this answered.
I figured that I was on the right track with one of the two scenarios but I wasn't sure which one.
Curious minds want to know!!!!!!!!

Kevin

[DIXONBOY]

It looks like the cyl. that fire together are 4/7 2/8 1/6 3/5. If you would like a copy I can email it to you.

[kstones63]

It looks like the cyl. that fire together are 4/7 2/8 1/6 3/5. If you would like a copy I can email it to you.

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