Misfire with new autolite double platinums

[tompumped]

I just recently changed out my motorcraft agsp32pp plugs, for autolite double platinum plugs. I didn't know the mileage on the motorcrafts that's why I changed them. Anyway I now have a miss occasionaly below 3k rpms under load. Has anyone had this problem? I never noticed a single misfire until I changed these plugs so I know it's the plugs. The gaps were good.
I'm about to try and bring them back to walmart without the boxes. 5 year warranty was written on the package. I guess i'll try the sp497s instead.

 

[Shopower400]

Are you sure you didn't cross a wire?? I'd do a search for the wiring schematic, and make sure. I've crossed wires several times, when i could've sworn they were right! The plugs should be fine.

 

[Big D]

hmm....

when you pull the plugs make sure they aren't fouled! BUT.. Before you do that, make sure all the wires are down on them! (you should here them snap on)

 

[Vnuk1]

 

[rubydist]

In addition to the possibility that you have a bad new plug (which does happen from time to time), you also could have damaged a wire when you changed the plugs. I've had both happen to me.

 

[tompumped]

When I got home the first thing I checked was if the boots were pushed all the way one and they were.
It's not a constant miss so firing order is correct.
I changed them out a few days ago, and today was the first day I drove a while and noticed it.
It only happened a few times under load below 3 or 2k. I just wanted to see if anyone has had any issues with these plugs.
I'm probably going to change them out when I finish the rest of the 60k, the front is done.
I changed them out because my gas mileage got worse recently, I don't know why I suspected the plugs. Stupid on my part because there was no misfire.
thanks

 

[1995SHO9]

Did you gap the new plugs?

 

[Mr Anonymous]

In addition to the possibility that you have a bad new plug (which does happen from time to time), you also could have damaged a wire when you changed the plugs. I've had both happen to me.

Exactly right.

I've seen this "only under load" situation a few times. It's always been traced to a bad plug that otherwise looks fine. If you still have your old plugs, just take one and start swapping it out for one plug at a time until the problem goes away and then you'll have identified the bad plug and can get it replaced under warranty.

 

[93rev2sev]

get it replaced under warranty.

Or unceremoneously tossed into a chipper.

 

[Big D]

Or unceremoneously tossed into a chipper.

Definitely more gratifying!

 

[tompumped]

I'll have to go through the trash to check for the old plugs.
I did gap them and I was careful, all the gaps were within spec except for one. I remember reading on another forum that you have to be very careful gapping any plugs with precious metals such as platinum or iridium.
I don't have a chipper so I guess i'll exchange it.