Alright heres my ordeal. I have a 2002 3.8 with a 5 speed and 116k on it. I bought the car with a hollowed out cat and a flow master. Recently I have had a misfire problem and its been going on for a few months now. I have replaced the 1st coil pack and the ignition control module since they seemed to have burnt out. That took care of the misfire for a little while. Now it started back up again! This time I had a spark tester and found out the #2nd coil pack was misfiring. So i decided to replace the 2d and 3rd coil packs and it seemed to have worked for about 10 minutes. Now the 2nd coil pack is STILL misfiring! I have also replaced the ignition switch as well because the voltage was gradually going down when the voltage was checked in the fuse panel. What the hell is wrong with this car?! I have searched on the forums but still didnt get a clear answer. Could it be the ground wires on the car? Or is there something that I am missing? Or is the voltage regulator messin up as well? (that was checked too by AutoZone and the volts were 13.8 to 14.1)

Parts that have been replaced so far:

1. Ignition control module
2. All 3 coil packs
3. Ignition switch

 

Voltage going down? Wire corrosion can do that and so can heat..

Give this a try.. get some water and a little bit of soap in a mist type spray bottle, and spray it around your coils and plug wires at night, and see if it jumps toward the mist. Also, check the gaps on the plugs on the 2nd coil. Check the boots at the spark plugs make sure they're all connected right.

I know it sounds silly, but also make sure the plug wires are not hooked up backward, no offense intended but it can be easy to do.

Do you know it's misfiring because of a check engine light?

 

Well lets see, I have been noticing the volt guage needle jumping arounda bit but when its hooked to a voltmeter, it stays consistant. As far as the gaps on the plugs, they cant be gapped due to them being the new style E3 Diamond Fire plugs. The check engine light was due to a catalyst effciency code and i believe that was from when the cat started to go out. After it went out and glogged the exhaust system, it was hollowed out. Could it possibly be due to the type of wires I have? Im not quite sure because the spark tester is hooked to the coil and then to the plug wire.... but i do believe they are 7mm wires. Ill check the ground cables and the voltage again. AS for the incorrect wire location, i double checked everything and even labeled the coils and plug wires when i first did the plugs and wires. I even printed out a little outline of the firing order and the cylinder banks using a label maker and just stickered it on the shock towers near the coils.

 

Also backprobe the primary ignition and make sure you're getting source voltage to the primary coil.

Did you use Dielectric Grease on the ICM?

 

Yeah I did use dielectric grase. i put some on the tabs where the coils sit and on the bottom where it bolts down to the bracket. As far as back probing, im not sure where to even start with that. my skills are limited with electric diagnostics.

I tried the soap and water and I didnt see any arcing anywhere. I still had the spark tester hooked up and it still missed. I cleaned all the ground wires I could find as well. Not sure if its the TPS or Crank P.S or the computer is going bad. Someone told me that with the cat being hollowed out, the O2 sensor was reading bad and that it was causing the miss. But wouldnt it be all the coils and not just the middle coil?

 

If it was the O2 it would probably be whatever bank the O2 sensor was bad on, but to cause a misfire it would have to be a lean condition, like pre-ignition. Besides, being a rear O2 it would just throw a check engine light, because all it does is confirm the Cat is working or not.

Since you run waste spark you would notice it on one cylinder and not the other, but you're saying it's at the coil implying it's both cylinders. That makes me think there is something wrong on the primary side of the coil. Which comes down to battery power and ICM... Unless you just got a bad coil..

This might be kinda strange sounding, but take an AC voltage reading across the terminals on your battery. It should be <500mvAC. Then do a DC voltage reading on your battery it should be 13.5-14.6V. Also do a resistance test on the connector side of the coil, it shuold be <5ohm and then do it across both plug wire connection points, it should be between about 5k-10kOhm. Lemme know what you find.

If your TPS was going bad, yeah it could misfire in certain areas of throttle position. If your CKP was going bad the car wouldn't start most of the time till the PCM got signal from it.

Where did you get coil from?

 

Lets see the first coil is from autozone and the second coil is from NAPA. The third is factory. I will do the tests u said to do and let u know. Thanks for everything.

 

Also, switch the coils around, and see if the problem follows the coil.

 

I switched eveything around and I even replaced the ICM again and STILL i get the same missfire. Check engine light came on and said I had a random missfire and thats why I replaced the ICM again. But still dont have any luck. Everything is brand new right now. Plugs, Wires, Coils, ICM. Not sure what else to do.