Gents,

I am at my wits end here. Hoping you can help me out. I have a 1997 4.2 F150 XL RWD.


My plugs that come with my rebuilt motor had 70k on them so i decided to replace. Went to Napa, and they didn't have Motorcraft, so i grabbed the Autolite Platinum and threw them in. Instantly my total miles per tank sunk from around 385+ to BARELY 350. And that was only if I was driving on the highway with a stiff tailwind.

After 2k or 3k miles I decided it wasn't worth the headache anymore so I went in to Advance and got 6 new Motorcraft plugs and replaced the Autolite. Drove around the block and almost immediately my engine starts misfiring so bad it throws the flashing check engine light.

I found out which cylinders were missing, looked at the plugs, and number 3 cylinder was ruined. After 5 miles. I was mind boggled with how quickly it went out. I took all of the plugs back out, compared everything to make sure I didn't miss something obvious like a different size or something, and once satisfied I put the 5 Motorcraft back in with 1 of the Autolite I had just replaced.

Now the truck is running perfectly fine, but I still am missing that extra 40-50 miles per tank!!! I am looking for advice as to what brand of plug might be out there to help me regain the lost MPG I am experiencing. I have looked into the E3???

Any help is greatly appreciated.

Thanks.

 

Go get another motorcraft one and replace that autolite crap

 

So I just need to take it on the chin on the 50 miles lost per tank?

 

I really like the E3 spark plug have ran it in three different vehicles and have seen a little increase in mpgs but not much. But I was also changing out half way new plugs nothing wore out.

 

I'm scared to do anything but use exactly what came in my truck. I've read too many stories like yours, but sure hope you can get'er back right!

 

If you venture from motorcraft I suggest ngk nickel. Was the rotor, cap, and wores changed on the rebuilt? Also how many miles on rebuilt motor? And how are all your filters?

 

When I put the rebuilt in I used a new coil, wires, and have kept up on air and fuel filters since I put it in. Engine has 50k on it. The MPG drop was distinct. I got about 18 before I changed plugs, and then once I got everything squared away with the new ones, I get 16.

I did see that the plugs that came out were Motorcraft double platinum that do not seem to be made any more. Do you think that is part of the issue? The replacement plugs i have in there are not double platinum, just single.

 

Man this is weird. What I would do is get a can of of spray seafoam and a can of regular dump the regular can in the tank and the spray can in the throttle body. Get a can of crc engine restore and that should get you your 2 miles back on top of 18. go back to all new double platinum or nickel plugs and if that doesnt do it upgrading all that has to do with the ignition system.

 

Thanks a lot. I am going to get some Autolite Double Platinum since it appears Motorcraft doesn't make them any more.

I will update once I have a few miles on the new system.

Thanks again.

 

Autolites are not spaced properly.