Coil Igniters

Same old 2.7 liter 98 4runner with auto tranny. On these engines, are the igniters for the ignition coils actually housed in the body of the coils themselves or 1) is the igniter a separate component by itself, or 2) is that function carried out by the ECM by itself? Recently found (by pulling the plug wires from the coils and then starting the engine with them close enough to fire) the spark from coil pack for the #2 and #3 cylinders has the proper blue white spark while the other one feeding the #1 and #4 cylinders has a yellowish and considerably weaker spark. Ideas here folks?:runaround: Recently replaced all the plugs - the old ones were worn but looked ok. Idles with a consisent missfire and the my shop hooked up his code reader to the brain and it came back reading one or two cylinders not firing.

It sounds like you need a new coil. Check the resistance of the plug wires, but most likely is the coil. Resistance of the plug wires should be 25 kOhms or less.

The igniter is separate from the coil, at least the troubleshooting guide says you can try a new igniter if nothing else is found to be at fault. There again, it wouldn't be the first time the manual has been wrong because of a new configuration. If an igniter is separate from the coil, it would be in the circuit just before the coil, in the circuit with a wire not supplying battery voltage to the coil when the ignition switch is on.

You can make sure the coil is getting battery voltage at the coil positive terminal. There is no good way to check a coil except by the appearance of the spark. Measuring the coil resistance with an ohmmeter is not very useful unless the coil is totally dead. Its performance under kilovolts is different than at the voltage used in a volt-ohmmeter. Coils are the most likely point to fail in the ignition system.

Thanks for getting back to me Brian. I replaced the coil and definitely have more power most of the time. Hit and miss right now on the misfire problem still. I'm going to do some random checks on the strength of the spark of both coils under different time frames and operating conditions to see if it is still the one coil giving the problems. I'll keep you posted about the results.