Factory Ignition Coil
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Senior User
Joined: Sep 2000
Posts: 385
Likes: 0
From: Flat Rock, Michigan
Factory Ignition Coil
I have a 81 F-150 4.9L with 187,000 miles. I am the original owner so I know everything under the hood is stock. The wires and plugs are new. I get around 15-16 MPG (with 92 octane) in the summertime and 12-14 MPG wintertime driving. Anthing less then 92 octane cause a nasty spark knock. The carb is a rebuilt 1 BBL. With the coil being 19 years old could it be slowly breaking down causing a decrease in performance?
Any suggestions on the coil would be very much appreciated here.
Any suggestions on the coil would be very much appreciated here.
Postmaster
Joined: Jul 1999
Posts: 3,172
Likes: 4
Factory Ignition Coil
That coil should be put up on the mantle when it does die .... Its hard to say with coils , sometimes they just die & then you have some that last as long as yours has been working . Its possible the spark knock is coming from carbon buildup on the tops of the pistons . The compression is raised from the carbon buildup so when you use a lower octane you get the knock . You might try using some Chevron Techron or other quality products designed to remove carbon etc to see if that helps .
