Hey guys,

I bought my truck, an '04 4.0 v6, with 80k on the odometer. From day one, the engine had always made this knocking/pinging that I had attributed to spark plugs. It only did it starting at 2500 rpm up a steep incline. I read in the owners manual that it is normal for these engines to have some knocking under load, so I just let it go at that. I changed my spark plugs the other day, and it made of world of difference, better mpg, smoother shifting etc. It feels like a new truck! However, the knocking is still there, only it has changed to about 2000 rpm and still only up big hills.

I replaced them with Autolite 5144, gapped to .54. The truck was still on the original plugs when I changed them, and the gap on these oem motorcraft was off the chart! ( as in it was so big my gap gauge couldn't read them)

So what would you guys do?? Change the plugs again? Maybe just regap them?? Or should I just accept the noise and live with it as I 've been doing? I really don't want to redo the plugs as it was a huge PIA, but....

I appreciate any input and experience ya'll can share with me.

 

Pull the plugs and check the gapping and make sure its at OEM specs on the gap unless you have an upgraded coil pack, gap it according to the upgraded pack

 

do not use any plug besides motorcraft double plats. i had the autolites too and the truck ran great except for pinging, no matter how perfect the gap was it would do it. soon as i put motorcrafts in it went away COMPLETELY.

you will never get the prob fixed if you dont get motorcraft. they were engineered around the engine, no matter how much ppl say "this company IS motorcraft, or this company WAS motorcraft" they arent. just spend the extra 10 bucks one time and get factory plugs.

 

You CAN run Autolite, or Motorcraft or even NGK as long as it's double platinum or iridium. The 5144 is a standard copper plug and I hope the parts person didn't just grab those to sell you. Anything with a coil pack or coil on plug MUST run one of these 2 style plugs.

Set the plug to it's proper gap. The pinging is caused more from weak voltage than anything else. Upgrade the coil pack with a new stock unit or a higher voltage aftermarket unit.

Never use those multiple ground strap plugs. They are a gimmick.

I'm running NGK iridium, NGK wires and an Accel coil pack on my 94 and at 206,000 miles it doesn't ping. On my 93 I'm running Autolite XP105 iridium, MSD wires and an Accel coil pack with 109,000 miles no ping.

25 years as a parts and mechanic jockey I've seen what works and what doesn't but I only use what I know works and only the best of the best on my babies!

 

ill go and pick up some motocraft plugs. do you happen to have the part number for the double plats?is . 54 the proper gap for the 4.0 v6 sohc?

 

Motorcraft # SP498. The gap is .054.

80,000 mile. Have you changed the fuel filter & pcv valve yet?

 

ya i meant .054 lol. half an inch would be a hell of a gap. i just changed the fuel filter but havent got around to anything else. will it damage my engine to run these copper plugs for a while or should i run out and get those motorcraft asap?
ps thanks for that parts number

 

It won't hurt it but they will wear out much faster. The old style copper plugs just aren't designed to run as much voltage. That's why they came up with platinum plugs. Platinum wears at a slower rate. Years ago copper plugs were the cats a**. Course coils put out 20,000 volts then. These days coil packs can generate 40,000 volts. Coil on plug even more so they came out with iridium plugs. Iridium is the hardest metal that conducts electricity but it is so rare. That's why they cost more.

Anyways the copper plugs will work but if left in will fail within 10 to 15,000 miles of not sooner.

Double platinum should go 75,000 miles provided you keep the maintenance up on your truck. Iridium will go over 100,000 on the same principle.

 

Well, I just stumbled upon my spark plug packaging. And it says right on the Autolite package "platinum" so i guess I installed the right ones after all. Maybe they have both copper and platinum under the 5144 number?? I got them at walmart for like $5 for two. Seeing as they are gapped correctly and are the right kind, do you guys still recommend replacing them with the motorcraft platinum plugs? The bastards are still pinging at 2k rpm so something isn't right here....