RE: eep! Motor stumbling, wanting to die
Michael, you never bothered to tell us anything about your car. A lot of Sherlock Holmes type deducing is required:
You're in the MarkVIII section, so I assume that's what we're dealing with.
You mentioned boots, as opposed to plug wires. This might mean it's a 2nd Gen. If it is, the diagnosis is very different than it would be for'93-'96.
Assuming it is 2nd Gen/OBDII, the PCM flashes the MIL while it is actively detecting an ignition misfire. If the misfire continues long enough, the light will stay on until turned off with a scan tool.
As soon as the PCM begins the misfire flash sequence, it holds a code in memory indicating which cylinder(s) it saw misfiring. This makes diagnosis much more accurate.
Trixie's right about the water entry. You'd be amazed how common that is.
COP coils are sensitive and prone to failure.
Engine oil is a great conductor. It doesn't take much to wick up the coil boot and give spark voltage a path to ground.
Once you get the PCM scanned and find out where the miss is, remove that coil from that spark plug well and turn it sideways so you can see the business end of it. Leave the 2 pin primary connector plugged in, run the car, and see if spark jumps out.
If it does, you need a spark plug.
If it doesn't, use a test light on the two wires to the coil. I prefer to use a "logic probe" type that can check for both power and
ground.
This part is no different than any distributor type or pack type coil.
The red wire (common colour on all coils) will have power with the key in the Run position. The other wire (different colour for each coil) will have a ground pulse from the PCM with the engine running.
If you've got power and a flashing ground but no spark, the coil is bad.
Now, if you're missing either one of those signals...
That's a can of worms we'd rather not open yet.
