I just wanted to post this as it might help someone else. My Bronco is a 91 302 with the 5spd manual. Good running truck. Today I noticed my plug wires were mismatched so I bought a new set along with plugs, cap and rotor. Installed them and went for a ride. The engine started pinging when I shifted to third gear under moderate throttle. It hadn't done this before I put in the new parts. I came back home and put the timing light on it. Timing was set at 12 degrees with spout disconnected so I moved it back to 10 degrees and drove it again, still pinging! Stopped and backed timing to 8 degrees, still pinging! Came back home and did a search on this site and found someone mentioned plug wires #7 and #8 touching could cause problems. I went out and checked and yes they were touching so I re-routed those two wires and went for a ride, NO PINGING! I reset the timing back to 12 degrees and still no pinging even in high gear going uphill. I was amazed! I have never even heard of plug wires touching causing this. Especially new wires. By the way the wires are 8mm Accels. Everything is good now and the truck is much smoother than before. I just wanted to say thanks to the forum and whoever posted that little bit of genious. If anybody is having problems with pinging, check those wires! Thanks guys.

 

I have never heard of that, but I will go home and look at mine. Thanks for the tip.

 

that is a known issue, running ford 9mm wires would help some but still important. Ive had bad luck with Accel wires.

 

There's a sticker under my hood relating to this wiring problem.
95 F150 302.