wcaskey

Looking for better gas mileage: I have (2nd owner) a 96 Ford F150 5.0L Automatic with overdrive trans. 94,000 original miles: Ever since I've tuned up my truck (2 years ago, maybe 5,000 miles) my gas mileage has decreased. I've pulled the old parts out and compared them: Original wires were 8mm Motorcraft -each numbered to match firing order with year 1996 on them. I replaced w/NAPA (Belden Max) Premium 8mm wire set (box & NAPA stated better energy flow & protection index). Plugs pulled out were Autolite 25; I replaced w/Autolite ASF42P. Mileage is averaging 13.39 without A/C on normal city/country with some hwy driving. Highway only w/o A/C on - 17mpg; all utilizing overdrive.

I just discovered wires# 5 & 6 were loomed next to each other (apparently a no, no because of spark over). Wires# 1 & 3 look to be loomed with greater distance as well. Any ideas how to get better mileage? Tires are inflated properly and automatic trans was flushed at Ford Dealership (a special additive was introduced by Ford for shuttering problem).

A year ago, after I tuned this truck up, I was driving through the mountains of TN, check engine light came on. Pulled over at another Ford dealership, they stated there were no specific problems, but they noted my spark was jumping all over the place (could this be because wire#5 & 6 were loomed next to each other). They told me don't worry, drive on. Light has never come on again. Gas mileage & power still stinks. Not ready to drop the cat. converters yet, but I need to get better mileage than this.

1: Any ideas on how to improve my mileage?
2: Should I revert back to the Autolite 25 plugs (thought hotter was better)?
3: Obviously cross spark can reduce gas mileage, but I've never heard of looming spark over issue with #5 & 6, then #1 & 3 before? At night I didn't see any physical evidence of spark over, but have just moved them (just to be safe).
4: Do I need to go back to O.E.M. 8mm Motorcraft wires? Not sure I understand why?
5: Is there something I'm missing to get better mileage?

wde3477

Welcome to the site!

What were the codes that were pulled? What was your mileage before? Have you pulled codes recently?

Plug wires should be OK - I put a set of the Belden blues on my Pontiac - no problems.
Plugs should also be OK.
Wires should not be crossed, but run parallel to each other. When they do have to cross - best to do so at 90-degree angles as much as possible.

A blocked cat is a possibility, as are any other issues that block air or exhaust flow.

Have to remember that a truck presents a large frontal area - lots of air needs to be pushed out of the way. One suggestion is to drive slower. I would be doggone happy to hit 13mpg on the highway, even more so the 17 you're getting.

wcaskey

Thanks wde3477. Happily, no codes have registered lately. Yesterday, I performed quite a bit of research and studied the old parts I removed 2 years ago when I originally decided to tune up my Ford F150 5.0L.

I found two articles discussing "cross talk" warnings about wires# 1 & 3 then# 5 & 6. I inspected and ensured these wires were clipped into the farthest channels of each loom. Even as they entered the distributer cap, I ensured they didn't come in contact with each other (used some of the other wires to twist/block between them).

I left the NAPA (Belden Max) wires on, but will borrow an Ohm meter to check my original wires. I guess I should have checked to ensure their resistance was greater than 20 Ohms, before I replaced them (but I didn't originally); lucky that I kept them around after replacement.

I reinstalled the original Autolite 25 plugs, which I had taken out, then put the Autolite platinum ASF42P back in their boxes. One mechanic told me the cheaper Autolite 25 is what is considered O.E.M. and that the less expensive copper plug has less resistance than the platinum plug, so it should perform better and get better mileage.

Checking mileage now, but I must say, I believe it's running better. I can state that I don't see the gas gauge moving quickly to "E" like I did after the tune up. Obviously viewing the gas gauge doesn't mean much, so I'm checking the mileage by the numbers. It does have greater response, now that the old plugs have been re-installed. More to come...

skidmarks

my ''90's 5.0 did worst on power after i got rid of the cats but only went with some blue thunder glass packs that i had on my 390 but went out both sides in front of the tires so i think if i went out behind the tires would of been a lot better or in front with turbo mufflers of some sort . but i had alot of fun driving it ,sounded realy mean then i blew up the trans mission and sold it to my bro's buddy for $3,400 and he put a flat bed on it. was a 3/4ton i kinda whish i kept it specialy after watching it pull a suburban out of a ditch with a ton of snow! my brothers 95 f150 was fast a heck and it was all stock. funny thing on that truck is he traded it for a 94 f250 with 460 and a week later the 95 got stolen from the dealer ship. he got an exhaust on the 95 and offed the cats just seemed to run weird with out them , i think if he had high flow ones might been better. thought some of this blabber might help with ideas for you ?