Cylinder misfire coil question

Hey guys!
So I was driving home from work today and for the first time my car started shaking pretty good for a couple seconds with the check engine light on.

It seems ok now (at this moment anyways) but my code reader pulled off cylinder 4 misfire.

Tomorrow I plan to pull off the coil that fires up cylinder 1 and 4 and test the ohms as per the factory service manual to see if it needs replacing, however I just have one question:

If a coil did go bad, wouldn't it throw two codes? One for each cylinder it's attached to? Since my car only through one code, should I assume its something other than the coil?

Just wondering where I should start with this.

 

I have no idea how the ignition is set up on an 02. Regular plug wires or a Coil On Plug design?

if COP...remove #4 coil. Switch it with a known good coil in another cylinger, like cylinder 3. Clear lights and restart vehicle. Does light come back on? Did the misfire move along with the coil? Replace the coil.

Quickest, simplest way of testing for bad coils. Move the coil, did the misfire follow it? If So, it's a bad coil.

 

On my 02, looks like I have 3 coil over plugs with dual plugs. Each coil over on the left side of the engine has a wire going over to the right side of the engine where it connects to a second cylinder.

I was going to try to swap as mentioned, but at this point the problem seems intermittent.

I haven't been able to reproduce the problem by just starting the vehicle. It only happened once so far on the hwy at about 90kmh

 

Most likey the plug wires for cyl 4. Just swap a wire from another cyl and see if the misfire jumps. If it doesnt, than its the coil.

Its easier and generally the problem.

 

Ah, just regular ol' plugs and wires. Not a Coil On Plug style. Wires run back up to a distributor correct?

-Check to make sure #4 is getting spark to it.

Several ways: (#1): if you have a spark tester, great! Install the tester and disable the fuel system, then crank the truck and make sure you have spark on that cylinder.

(#2, backyard style, requires a helper person): Remove the wire from the plug. Remove the plug. Place the extracted plug back into the loose plug wire. Ground out the plug wherever you can. Again, fuel disabled and have helper person crank motor. Does plug have spark?

If #4 is getting good spark, move on from there.

-Check the plug gap and condition of plug(s). And overgapped plug will cause a misfire. A plug by it's self can go bad. Excessive whiteness or blackness of the plug and ground is a definite issue, however an even browning of the plug is considered more normal wear.

If it's got a distributor, check that out next. Make sure to know where all the wires come and go before disassembling. Remove the cap and check it. Are the contacts nice and clean or they look worn out, used and got white crap building up around them? Or are the contacts black and burnt? If anything looks even slightly fishy, replace it. Check the rotor button for the same kind of wear as the cap. Replace it if fishy.

Check some of that stuff out, post up any pics you feel necessary.

 

Crap, I should have mentioned I have the v6, and it is coil over plugs on 6 of the 6 plugs.

Drove it today without any issues. Intermittent it seems...

 

The reason why it won't show a misfire for the other cylinder (typically) is based on how misfires are calculated out. It does not measure spark or anything like that at all. The crankshaft sensor measures the revolution of the crankshaft. When the engine is running normally, it sees a smooth signal from the sensor. If a cylinder misfires, the engine speed will slow down at that point. YOU detect it as a shake, the computer detects it as the crankshaft speed not responding like it should. Since the engine knows which cylinder it just fired, it knows which one is the culprit. Also the cylinder has to misfire several times before it will set a code.