Truck is running rough. Pulled off the plug-wire connections to the coil pack and found the pin and coil pack connection on #3 corroded, not shiny like the others. Cleaned it up but truck still runs rough. (Runs just as rough when I disconnect #3 altogether).

Now it's one of three things. Plug...wire...or coil pack. Is there an easy way to check a coil pack to see if it is the culprit before I replace the plug and wire? Also, why would the connector corrode like it did?

Thank you in advance. Any help is always appreciated...Scott

 

<edited 'cause I thought COPs, not coil packs>

If the #3 wire or plug was compromised at one time or another (dead skip or whatever), it'll overwork and damage the coil pack. If it's been ran for any amount of time with that misfire, it's very possible that the coil pack is bad.

 

Problem started yesterday during a trip to the SPCA. Rainy that day (if it matters at all) and truck ran fine getting there, but when I started up for the return trip, started running rough and CEL went on, steady at first, then blinking. Trip was about 30 miles and took about 50 minutes. Is this enough time to kill a coil pack?

 

Possibly. I dunno what the resistances are for checking one of those things off the top of my head, so I honestly can't give you any specific methods of testing 'em. If you were closer, I'd give you one of my known good test coils and see if it helps any. Hopefully someone better versed than I will be along shortly to give you some more info. Sorry I ain't worth much more right now.

 

Just bumping this up to see if I can get any more responses...Thanks

 

You can test the COP's easily with an ohmmeter. The primary coil should read .55 Ohms, secondary(spark plug tip and pin 2) should come in close to 6K ohms.

 

Im not sure what year the truck being tested is but I believe it was described as a coil pack, not a Coil On Plug.

My Haynes manual for 1997 thru 1999 Electronic Integrated EI Systems shows Primary resistance of 0.3 to 1.0 ohms and Secondary resistance of 6.6 K-Ohms to 11.5K-Ohms.

 

Fantastic guys...exactly the info I was looking for. Will test them tomorrow.

If I could, I'd buy you all some

Thanks again...Scott

 

You're getting way ahead of yourself. First, besides the corroded connector, what makes you suspect that the #3 coil is bad? You mentioned that it was rainy and that the your CEL came on. Did you have the code pulled for the CEL?

Here's what you need to do - go to AutoZone and have them pull the codes. If its a missfire, the code will tell you which cylinder. Next, remove the COP (assuming this is what you have) that is indicating a missfire and check for moisture in the spark plug well. If there is not water or moisture in the well, then you will need to purchase a new COP. Cost is about $50 at Autozone. Replace the bad one with the new one. This should solve the problem. If there is moisture in the well, remove it and reinstall the COP. If the truck runs ok, problem fixed. If not, replace COP.

Lastly, checking the resistance on the COPs is useless. The only real way to tell if the COPs are going bad is to test them while under load. You can only do this if you have a 'high-dollar' scanner or by taking it to the dealer. Trust me on this - I've 'been there done that' with these COPs. They are a pain.

Also, you should post the year and model of your truck/engine. Would help us when trying to provide advice.

Hope this helps.

Anthony