Wrong spark plugs / 96 crown vic cng

[pollitosrus]

Does anyone know if using the wrong spark plugs would cause a misfire? My local mechanic put in the AGSF-32-FM and they worked for a while but now i am getting a backfire. New wires and replaced coils. Now i am finding out the CNG needs AGSF-22FM1-F4. Would those other plugs make that much of a difference or should i be looking for another reason for the misfire ??

thanks

[Mshepcomm]

Re: Wrong spark plugs / 96 crown vic cng

I don't know if this helps but I was having a bad misfire on my 1999 Vic.
It turned out that it was just ignition.
I had 2 bad coils and a few questionable plugs. We replaced my plugs with new Autolite XP103's, $5.99 each at Kragen, and I took someones advice and replaced ALL my failure prone Ford Coils with a set of Hi-Performance MSD Ignition Blaster coils, P/N 82428, about $390 for the set of 8.
Mine was bucking and running like crud before, and now she purrs like a kitten at idle, and goes like a bat out of ....

[smartineau]

Re: Wrong spark plugs / 96 crown vic cng

Your car has distributorless ignition. Basically the spark leaves the coil, jumps the gap of a plug (porcelain to ground), runs through the block & then jumps the gap of the companion cylinder (ground to porcelain) and returns home to the coil that created it. Every time a spark jumps the gap it carries a small amount of metal with it (elecrolysis) which is why the plug electrode rounds off. The wrong plugs on your vehicle can start to cause a miss (sometimes in less than 5,000 miles) caused by electrolisys fouling the porcelain side of the negative spark plug.
You should be using double platinum spark plugs. Without going into an in-depth discussion I tried to answer your question as to what happened & why. The parts house will always show (and many technicians will use) the least expensive plug because they are focused on the consumer understanding only one thing -- cost. There are a lot of complaints when you install an $8.00 spark plug when the guy down the street only charges $1.95 because the consumer has no idea what the difference is. They see only the price.
Stan