2003 Tacoma, V6. A few weeks ago I started getting a misfire. Read the codes, misfire on #3 cylinder. I swapped the #1 coil & #3 and the misfire moved to #1 cylinder so I knew it was the coil. Changed the coil, problem solved. A week later #3 cylinder misfire again. But since I had swapped with the #1 I thought maybe all my coils were going bad. Changed the coil, problem solved. Now, a couple weeks later, #3 cylinder misfire again. I checked the resistance in all three coils and they're all pretty close to eachother. Now I'm lost and done throwing parts at it. Any ideas?? Thanks

 

Fuel injectors...check those. They tend to be behind these type of mysteries...

 

Would the injector make the coil go bad?

 

I can't speak from experience on the issue of injectors, but it would make sense to me a bad injector could result in damage to a spark plug. When your spark plug is damaged and cannot ground or "spark" it will ground back out through a coil pack. This could be the reason #3 keeps blowing coil packs. Check your plug first, then move on to injectors on that cylinder. Either way, its something in there that keeps blowing packs. Check for burn marks around the screw holes on the coil pack as this would be an indicator of faulty grounding. Keep me posted, Im curious...

 

More infomation that I didn't put down before: Engine only misses under load, not at idle, and not when reved in park. Checked all the plugs, they looked fine. New plug wires.

 

Did you use OEM plugs?

 

Yeah. I just replaced them with plugs from Toyota, cleaned the MAF sensor. We put it on the diagnostic computer and everything looked good (after i replaced the coil again). So, guess I'll see if it develops again. It wouldn't surprise me if it was the old plugs.

 

bump....stlstrs, did you ever get this issue resolved? I'd love to know what ended up being the problem.

 

Sounds like injectors to me as well if the injector is burnt it will dump too much fuel in and cause a misfire especially under load Fouling the plug!!! Coils most likely are not at fault!!

 

I did get it fixed. I was just thinking the other day I better post my results.

The best I can tell is the gap on the spark plug on the #3 cylinder was too big, making the coil work too hard. When I first check the plugs, they looked fine, but after comparing them to new plugs, the gap did look too big. I just did a general tune up and it seemed to fix everything. I had 3 coils go bad in a month, now is been 3 months and no problems and the truck runs great. I guess there is something to be said for the good old fashioned tune up.

Thanks for the help.

 

always tune up when misfire occurs to eliminate cheap aspects first

 

Should be using dual-ground spark plugs for the V6, which do not require gapping. (Even if you wanted to gap them, you can't.)

 

you can gap them you just need a wire gap tool.
http://www.google.com/images?q=wire%...w=1136&bih=688