Coil Pack

Hi,

I'm still working on a misfire code on my #4 cylinder. I was going to swap out my coil packs and see if the misfire goes to another cylinder.

I noticed on my coil packs the original packs have the number 1 and the number 4 on them.

Do these coil packs send a charge continuously or are do they send the charge at TDC of the firing cycle on each cylinder.

TDC firing of number four is exhaust cycle of number 1. Charge goes out to both cylinders.

Or is the charge separate ? Only goes out to the cylinder when at TDC firing. The other plug is not sparking. Which means separate interior circuits.

I'm assuming the numbers on the coil packs were for ease in assembly. That there's no difference between the two packs and they are interchangeable.

Thanks

Lou

 

I'm not sure, but some engines use a "lost spark" firing sequence.

This only means the "lost spark" happens on the exhaust stroke of the piston.

My ol' motorcycle uses a lost spark ignition. It was made in 1981.

Yes, coil packs can be installed (swapped) to any cylinder. They are not specific to a cylinder.

 

Hi,

Yes, the old Triumphs I rebuilt used the lost spark at the top of the exhaust stroke too.

I did not mean they were sending voltage to the spark plugs continuously. But that they were sending the spark out simultaneously to both plugs.

Assuming they are only sending the spark when one or the other is at TDC of the respective firing /exhaust stroke.

If the coil packs have one circuit inside then I don't see how it could be any other way.

The point is that I see a lot of people buying new coil packs when they have a misfire on one cylinder , yet the coil pack serves two cylinders. Which means that you would only need a coil pack if the two cylinders the coil pack served were misfiring. Unless the circuits in the coil packs were separate.

Anyway, I'll swap out the coil packs and see what happens.

Thanks,

Lou

 

The coils charge until they receive the "fire" signal from the engine ECU.

 

Yes, from the ECU. Which means the signal is going to two cylinders or to just the cylinder that is at TDC to fire, which means separate circuits in the coil.

 

One zap goes to two cylinders simultaneously - one at TDC on compression stroke, the other wasted on the exhaust stroke of the companion cylinder.

 

The "zap" does not come from the ECU. The "zap" is from the coil's built up charge. Each cylinder has its own coil.

The ECU only sends the "fire" signal, although it may send the fire signal to 2 cylinders simultaneously.

 

My engine has one coil that has two wires each. 1 and 4 and 3 and 2. I just swapped them out. Total of two coils. The terminal on each coil has four tabs which might mean that each spark plug wire gets a separate signal to blast off.

 

Negative, this is a waste spark system. There's only half the number of coils as plugs. One coil is wired to two plugs.

 

Ok......based on your description......

YOU have 2 coils each firing 2 cylinders. I assume there is a spark plug wire running from the coil to each of it's cylinders.

I suspect when the ECU fires each coil, the coil "unloads" to both it's cylinders at the same time, one will detonate the fuel/air mix, the other will be "lost spark."

Your misfire is on Cylinder #4, not on #1. This would eliminate the coil as the problem. Do a close inspection of the spark plug wire. Look for insulation cracks, bent terminals....... Or you could try an old school method. Run the truck after dark, no lights turned on, watch for arcing from the plug wires.

Or completely swap the coil positions, be sure to maintain the correct connections from the coils to it's respective cylinders. If the misfire remains on #4, then the coil has been eliminated as a problem.

 

...and your results?

 

OP.....have you pulled the spark plug from cylinder #4?

If so, what is it's condition?

 

Give me till tomorrow afternoon. I need to put in my new fuel filter which arrived today. Denso. Looks like a perfect fit. Will update on the fault reading then.

Thank you,
Lou

 

Doesn't look any different than the other three. They are new but look a bit dirty from a rich mixture.

 

I guess I should've been specific. The plugs from the "misfire" code. Not the new replacement plugs.

 

You can test the coils with a multimeter. There is a procedure to test resistance to determine if it is bad. Let me see if I can find my post with the instructions...

Found it...

(c) Inspect the primary coil resistance.

Using an ohmmeter, measure the resistance between the

positive (+) and negative (–) terminals.

Primary coil resistance:

Cold 0.67 – 1.05 Ohms

Hot 0.85 – 1.23 Ohms

If the resistance is not as specified, replace the ignition coil.


Inspect the secondary coil resistance.

Using an ohmmeter, measure the resistance between the

positive (+) and high–tension terminals.

Secondary coil resistance:

Cold 9.3 – 16.0 Ohms

Hot 11.7 – 18.8 Ohms

If the resistance is not as specified, replace the ignition coil.

 

Hi,

Back again. Started early. Got the Fuel Filter in. So easy and quick to write that. Completely opposite the angst of figuring out how to reinstall once you have it ready. I guess that was an hour and a half later. Put the tire back in place, etc. Started the truck and she ran smooth. Buuut was stalling out. So I got back under the hood and found a vaccum hose disconnected. Those things are critical. I got the OBDII in place and the torque APP going. Crank it up and it's running smooth and stays at a good idle. I have no fault codes and she's not misfiring. So far so good. Took it for a spin and everything is smooth except there was some hesitation. It runs smooth but there was some surging. I'll keep driving and see if it goes away. I left the coil packs flipped since everything is working. No point in changing them back. Could throw everything into a tail spin. No water on the number four plug. Must have been when I sprayed the engine bay. What a relief that is. Thanks for all the help. Not real sure if there was a serious problem in the first place but the new fuel filter did not hurt anything. Let's hope this stays fixed.

Thanks again,

Lou