Should I change my plugs and wires for +gas mileage?

[spta97]

Let me start out by saying I've got a 2000 5.0 V8 AWD with 36k miles so please no numbers from the V6's around here (I get jealous ). I've done the following in an attempt to increase my gas mileage:

Flushed Tranny and changed filter
Run tires at 35 PSI (255/70/16)
Changed air filter
Changed fuel filter
Took to the dealer

Out of those things, the tranny flush seems to have boosted the most (about +3 MPG). However, I'm still only getting 13 MPG highway and city is just aweful (60 miles on 1/2 a tank!).

I'm wondering if chaning the plugs and wires would help. I've dumped a lot of money into it (not only the above, but many other things) and I don't want to change plugs and wires if it is not going to help me increase my gas mileage. However, I've spent over $200 in gas just in September so I'm looking to increase my gas mileage to what the other AWD V8's are getting.

Will the wires and plugs make a difference?

 

[Joey P]

If the plugs and wires are bad, then it might make a difference. Maybe only 1-2mpg more though. I just replaced my Plugs/wires and they weren't that bad but I did gain 1 more MPG to up my MPG to 17mpg!

 

[spta97]

Are you getting 7 MPG on an AWD / V8?

Also, how can you tell if they are bad?

 

[Joey P]

No, I'm getting 17 mpg on an awd V-8. I do mostly highway driving so that may be why. In the city....I'm not sure what I get. I'm also not sure how you tell if there bad but when I compared them to the new ones, they just look "wore" down. Plus I had 115,000 on mine and the plugs had "motorcraft" printed on them. I assumed they were the original plugs.

 

[spta97]

Is there anything else you did to get that kind of mileage? I would kill for that. I just don't want to dump in wasted money if it's not going to help. I would gladly throw $500 in the engine if I knew it would pay back in better mileage. It's not the amount of money, it's wasting it that I don't want to do.

 

[SilverBullet]

Wow ,that's crazy.. I get about 17 mpgs city/highway, and I'm no easy going driver. I usually get about 325 before I have to fill up, a couple weeks ago I got 350 before I had to fill up.

 

[Electrohacker]

I get 17.5 mixed 20 + highway and wel over 360miles on a tank and my engine s over 141000mi... I still think the previous owner modified it a little since he worked at bosh automotive and all

 

[Ford_Racing_Guy]

i've heard that the throttle body spacers work wonders

 

[aldive]

Take a look at http://www.explorerforum.com/forums/showthread.php?t=44372&highlight=quest .

The test truck is a SOHC V6, however, the same principals should apply and help your mileage.

 

[CdnCory]

I changed my plugs and wires not long ago and my plugs were in rough shape (if anyone remembers my thread ), and I got a increase of 0 MPG.

 

[spta97]

I get 17.5 mixed 20 + highway and wel over 360miles on a tank and my engine s over 141000mi... I still think the previous owner modified it a little since he worked at bosh automotive and all

Wow - 250 is the best I can do on a full tank on the highway with low RPMs. Have you done anything?

 

[spta97]

Take a look at http://www.explorerforum.com/forums/showthread.php?t=44372&highlight=quest .

The test truck is a SOHC V6, however, the same principals should apply and help your mileage.

I'll have to give it another read, but since it was a V6 I didn't think things would work for me. If people are getting 17+ MPG without trying it makes me think that things are seriously wrong with my truck. However the power is good and it feels fine driving it. I'm hoping to stumble over one engine component that gives me a +4MPG increase. What that is has eluded me thusfar.

And eluded the dealer as well

 

[barneyrubble318]

I've got a '97 AWD V8 Eddie Bauer with 97k. The transmission fluid, plugs and plug wires have about 35k on them. I've got a K&N filter in the stock box. I get 16mpg if I set the cruise to 65mph. If i drive with out cruise it jumps to 17.5 or 18mpg.

I noticed quite a bit of difference when my plug wires went bad. I thought the tranny was going out. It would shift funny at highway speeds, felt like I was hauling a trailer. Ended up it was missing because of bad plug wires. The O2 censors can lower the mpg when they start to go out, too.

Anyway, I've found my driving habits make the biggest difference. Octain would be the next thing, 87 vs. 91 seems to be about 1.5 mpg. I normally get the 87 now. No pings either way. The K&N air filter didn't make much of a difference, but when it is dirty, the mpg drops.

Does anyone get 18mpg and still drive like a maniac? What bolt on parts give the most milage? Exaust or intake? Throttle body spacers? MAFS? Cutting holes in the stock air box for cold air?

 

[aldive]

I have a friend with a bone stock 99 5.0 awd and she gets 21-23 MPG at highway speed.

The concepts I use should apply to all motors.

I think that either its your driving style or you have some unknown problems with your truck.

 

[spta97]

I have a friend with a bone stock 99 5.0 awd and she gets 21-23 MPG at highway speed.

The concepts I use should apply to all motors.

I think that either its your driving style or you have some unknown problems with your truck.

Well, I just got through 8 pages of the thread and it seems that the driving style would dictate a lot. Last winter I didn't let it go over 2.5k for a whole tank and it made no difference at all. Good thing because I drive agressive

I'm hoping it is something wrong but I have no idea what - that's why I was looking at the plugs / wires.

 

[2NRFIXR]

Well, it's not just rpm level that may affect mileage but also throttle position. Meaning you can gradually let the tach go to 2500rpm or you can mash the pedal just to the point before it would down shift after each upshift to 2500rpm and get worse gas mileage. Simply put, a good rule of thumb is the g-force you feel, not just rpm level will dictate your mileage. Just drive like you have a full cup of coffee in your your cup holder and you're trying not to spill it (like me 99% of the time) and your gas mileage will increase!!!

 

[Electrohacker]

Wow - 250 is the best I can do on a full tank on the highway with low RPMs. Have you done anything?

all I did was run 34 psi in the rear and 32 in the front.... I took a look through all the parts of the ruck once and saw a lot of bosch electrical parts... I figure since it was a bosch company truck and was used to test parts in... some of those parts mihgt have stayed in it... besides the fact that the V8 makes more power and can move the larger frame better than the V6...

 

[4FordFamily]

Well let's see...

My truck had 130k miles on it before my spark plugs were EVER replaced. That's right, i had the original motorcrafts.

The best part of all is how the spacers were WAY off, probably double the space they should have been.
2 were apparently misfiring.
They were ALL in VERY BAD condition.

My check engine light keeps comming on (i was told it was likely an O2 sensor but who's to say)

Well so i replaced the wires with BOSCH premium and put BOSCH Platinum series +2 plugs in there.

Not only did i notice a smoother acceleration, faster acceleration, quieter running and calmer idle, My gas mileage increased SIGNIFICANTLY. So much so that my gas tank lasts twice as long. (I would go ahead and check my gas mileage but i never seem to be able to do it) Lets just say formely i was lucky to get 200, Now i likely get around 275-300

Sorry, i am a V6 but the purpose of the post was to tell you that if indeed your plugs just plain SUCK then yes it can have a major effect on your gas mileage.

Now what the hell else is wrong with my truck? (the question)