So I did a tune up on my 94 with a 4.9 before i leave for my trip tomorrow and it took three days because the first day i did plugs wires cap and rotor. well it ran great for about a half hour then it acted like it was missing. so the next day i went and checked everything out and noticed the yellow wire goin to my coil was showing wire. so i went back and redid all of that. and still the same thing, i was stumped. so this morning i went to the parts store and got a set of cheap motocraft plugs and put them in place of the autolite platnums that i had gotten a few days before. and it runs just fine, ive been drivin around all day to make sure it would work, and not a problem.

My stepdads friend said that platnum plugs run hotter and that my engine didnt like it. oh also when i took the autolites out the electrodes were a tanish color, like it was burning right. i was just wondering if anyone else has ran into this before?

 

All I've ever been happy with in the 300/302/351 are the simple motorcrafts.

Adrianspeeder

 

Yep. These old engines don't like Platinum plugs. Cheapo Autolites from WM work the best.

 

Yeah, I also found out the hard way that the 4.9L just doesn't like platinum plugs. It does, however, have a perpetual hard on for Champion Truck plugs.

 

Nice

 

Yeah dont spend the money on platinum plugs unless your engine was designed for them and always use a plug thats similar to the oem. Motorcraft, Champion, and Autolite (copper) work good in domestics. NGK plugs are good in most imports and Bosch work good in euro cars. Thats my opinion anyway. I've seen lots of drivability problems in Toyotas caused by Autolite and Champion plugs.

-Jon

 

Platinum plugs actually have higher resistance and require more voltage to deliver an equivalent spark. They are really only useful on engines which employ a "waste spark" technology to assist with emissions control.

 

I've noticed that type of thing. My GTP HATES Bosch plugs, but my friend's Saab loves them. If I run the Bosch, I'm lucky to get more than 500 miles on them, wheras he has 20,000 and still going.

 

Well, how's about this for timing!
My truck has had some 'platinum' plugs in it for the past 3000-odd miles, and today it started missing... Off to ford tomorrow for some boggo motorcrafts

Interstingly, in my boosted mini all i ever run is Champion C57's or Motorcraft racing plugs. NGK's are horribly unreliable to the point I swear I'll never buy any NGK's ever again...

 

Thats all I've ever ran in my truck is autolites or motorcraft plugs. I also found that Fram oil filters dont mesh well with my truck either. I usually pick up the FL-100 filters or Penzoil filters.

 

Autolite 25s is what I use in my truck. Anything Platnium is garbage.....