Autolite Platinum Plugs Suck

[nofordstranger]

I bought this 1998 Ranger about 1 month ago, it was running bad but I got a great deal on it. It was misfiring big time. You could see that the previous owner had replaced everything he could think of, he had installed a set of Autolite Platinum Plugs. I replaced the plugs he put in with another set of new Autolite PP's and the truck ran great, for about 3 or 4 days then the misfire came back. For about 2 weeks I tried to figure out the problem, finally after trying everything else and replacing parts that werent bad, i installed a set of Autolite 103 copper plugs and now it runs great. I have had same problem on other cars ive owned. I put some new platinums in my toyota and ended up taking them out the same day and putting the old ones back in. I will use the good old proven coppers from now on.

 

[bhawk]

Were the Autolite plugs single platinum or double platinum? The reason I ask is because the Fords must use a double platinum plug once you replace the original Motocraft plugs. Apparently, one bank of cylinders fires from the bottom up on the plug, and the other bank fires from the top down on the plug. So, a single platinum plug won't hold up on 3 of the 6 cylinders. But a double platinum plug, which means both "tips" of the plug are made of platinum, will work fine. The above might explain the failure.