18MPG around town on 03 5.4l

[Jdcline54]

So it started out with a p0304 and right bank lean code. After doing a little reading I came to the assumption that it was cops and plugs. So I avoided doing the job for 2 years because I was afraid after what I had read...2 years later it got bad enough I had to fix it.

So without doing any diagnosis at all I swapped out the plugs and cops, using motorcraft of course. Didn't use liquid wrench or anything, just light pressure and a combination of extensions und universals. Everything went as smoothly. It was obvious that the right bank was running super lean, wish I had done it sooner..

After getting it back together it ran smoother with no codes appearing, but still had a slight miss that was hard to notice. Couldn't figure it out so I went to basic thinking..

What does an engine need to run?
Air, fuel, compression, ignition.
I had fuel and ignition for sure so I ran compression and got some funky results. Moved to leak down and everything showed fine. Found out I was doing compression tests wrong, redid it and all was good.

At this point all that was left was the air factor. So I went to the shop at the college and ran smoke through the vacuum lines. There was the problem... Smoke poured from brake booster, EGR, lower intake, and valve cover on left side. Spent about 120 bucks fixed all this, which was relatively easy no special tools required, except Ford fuel line tool. (which I made from a sharpie lid) the result was 18ish MPG around town 25ish on freeway after 200 miles.

Imagine how much time, energy, and money I could have wasted with properly diagnosing the issue..

Moral of the story:
Stop throwing parts at an issue until you know what it really is.

I was ready to pull and rebuild or replace the motor.. Or drive it off a cliff... That sure wouldn't have been cost effective.

 

[Gary Waugh]

That is a great MPG for town, you must drive like a saint!! I only manage 14mpg in town!

Gary

 

[Esat]

View attachment 27639
So it started out with a p0304 and right bank lean code. After doing a little reading I came to the assumption that it was cops and plugs. So I avoided doing the job for 2 years because I was afraid after what I had read...2 years later it got bad enough I had to fix it.

So without doing any diagnosis at all I swapped out the plugs and cops, using motorcraft of course. Didn't use liquid wrench or anything, just light pressure and a combination of extensions und universals. Everything went as smoothly. It was obvious that the right bank was running super lean, wish I had done it sooner..

After getting it back together it ran smoother with no codes appearing, but still had a slight miss that was hard to notice. Couldn't figure it out so I went to basic thinking..

What does an engine need to run?
Air, fuel, compression, ignition.
I had fuel and ignition for sure so I ran compression and got some funky results. Moved to leak down and everything showed fine. Found out I was doing compression tests wrong, redid it and all was good.

At this point all that was left was the air factor. So I went to the shop at the college and ran smoke through the vacuum lines. There was the problem... Smoke poured from brake booster, EGR, lower intake, and valve cover on left side. Spent about 120 bucks fixed all this, which was relatively easy no special tools required, except Ford fuel line tool. (which I made from a sharpie lid) the result was 18ish MPG around town 25ish on freeway after 200 miles.

Imagine how much time, energy, and money I could have wasted with properly diagnosing the issue..

Moral of the story:
Stop throwing parts at an issue until you know what it really is.

I was ready to pull and rebuild or replace the motor.. Or drive it off a cliff... That sure wouldn't have been cost effective.

Tell us about the smoke testing and the fixes you made a bit more (a lot more)[emoji16]


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[Jdcline54]

Gary, when I'm driving with my foot in it, I manage about 15.5 to 16.

Esat, you want more details for real? Or was that sarcasm? Lol

Because this is the short, edited post. Lol but if you honestly want details I'll post them.

 

[Bain64]

Gary, when I'm driving with my foot in it, I manage about 15.5 to 16.

Esat, you want more details for real? Or was that sarcasm? Lol

Because this is the short, edited post. Lol but if you honestly want details I'll post them.

He's serious, and if he isn't I am. Yes please share more about the experience with the smoke test and subsequent repairs.

 

[Gary Waugh]

yes, I was serious, I can't get anything like the MPG you are getting around town. I have not heard of the smoke test and would be interested in hearing how it is performed. Don't think I have a leak but always like to learn new techniques to find problems. Please share..

Gary

 

[Esat]

He's serious, and if he isn't I am. Yes please share more about the experience with the smoke test and subsequent repairs.

Dead serious, I would like to learn and check my expy ,if it will go 18 in City.

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[Prince_Polaris]

Woah woah woah you're getting 18MPG with the 2003's 5.4L V8????? I GET NINE POINT SIX! D:

 

[Trainmaster]

... I thought better of what I was going to say....

 

[Esat]

Reality is on highway 14 miles or so



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[Prince_Polaris]

I need to remember that because I live in western maryland, my MPG is gonna be lower than all of you guys who live in flat states- everything out here is a mountain!

 

[Jdcline54]

okay.. Sorry it has taken me so long to reply...

So a smoke test is for finding vacuum leaks. because if you have a vacuum leak you have air entering your system after the MAF sensor, which is unmetered air. the computer adjusts fuel/air mixture based on what the sensors have told it, so if you have unmetered air the air fuel ratio is out of line from what it should be, thus creating a lean condition...

That being said, a smoke tester is a machine(that happens to be very expensive) that you hook into a vacuum line or directly into the air ducting that goes up to your throttle body/intake. it's forced in with compressed air to pressurized the system with smoke...then you just stand back and watch for anywhere you see smoke leaking out, and Bam! you know what to fix...

In my case I had smoke coming out from the lower intake area, and the EGR valve. also had some coming out the power brake boost plug but that was fixed simply by pressing it in a little better.

so at that point I knew without a doubt that I needed lower intake gaskets and an EGR valve. once I got the Intake off I discovered that I had a leaky valve cover gasket also. so I went ahead and changed them all... Upper/Lower intake and valve cover, along with the egr.. BOOM 18 MPG! Also I should note, I live in a mountainous region of Utah...So if I can get 18 so can you.

Now as I mentioned the smoke tester being expensive...like $2000... don't worry, I know of a cheaper alternative. dang near free...If you have a little bit of D.I.Y. skill.

Heres a couple links to a diy video for a smoke tester:

I don't really like this one, but its super cheap and easy.

This dude is kinda ghetto, but his method use compressed air rather than a bike pump which would work better, in my opinion.:

 

[Dwilds]

Woah woah woah you're getting 18MPG with the 2003's 5.4L V8????? I GET NINE POINT SIX! D:

I second the 9 MPG. With a newly remanufactured engine.


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[ExplorerTom]

I need to remember that because I live in western maryland, my MPG is gonna be lower than all of you guys who live in flat states- everything out here is a mountain!

The thing about hills though is that going up hills isn't nearly as inefficient as going down hills is efficient. Meaning: if 14 mpgs is a good "flat" terrain average, going up a hill may drop you down to 6 or 8 mpg, but coming down a hill can see 75 or more.

At least that is my experience. Any time I have a tank of gas that includes mountain driving, that tank is always noticeably better than a tank where I stay out of the mountains.

 

[Plati]

The thing about hills though is that going up hills isn't nearly as inefficient as going down hills is efficient. Meaning: if 14 mpgs is a good "flat" terrain average, going up a hill may drop you down to 6 or 8 mpg, but coming down a hill can see 75 or more.

At least that is my experience. Any time I have a tank of gas that includes mountain driving, that tank is always noticeably better than a tank where I stay out of the mountains.

I enjoy math and physics ... so this is a fascinating observation. I don't doubt your experience. Intuitively it seems like it would be a wash, not an increase in gas mileage. Reminds me of riding my bicycle through West Virginia. I would struggle to make it up a steep hill and then coast down the other side. Overall it was a lot more brutal and took longer (for a given distance) than in Kansas.

There are a lot of factors with the mountains in Colorado. Its cooler so maybe you're not running air conditioning at elevation? Air is thinner (and cooler) at elevation so engine combustion "efficiency" is different. Air resistance is also lower at elevation. Might be going slower than on an interstate on the flat? Many factors besides just uphill vs downhill.

If I run the numbers to compare 1000 miles on the flat vs hills (assuming 50% duty cycle). Assume 10 mpg uphill, 100 mpg downhill, 18mpg flat. You end up burning about 55 gallons either way. OK I'm a geek!

 

[ExplorerTom]

I'm also basing this on my observations of the "instantaneous mpg" readout on my OBD reader. Going up the mountain, I'll see it drop to 7ish while flogging the engine: 65-70 mph at 4000 rpm going from 9,000 feet to 12,000 feet over the course of a couple miles. Going down the other side, coasting, it'll read anywhere from 50-90 mpg.

You'd think, based on those numbers, my combined average would be significantly biased to the higher numbers. But if my normal average is 13, a tank with mountain driving might be 15. 2 mpgs isn't much, but it is noticeable and it seems to be repeatable.

If my dad used to walk uphill both ways to school, why can't I drive downhill both ways to work?

 

[Jdcline54]

I'm also basing this on my observations of the "instantaneous mpg" readout on my OBD reader. Going up the mountain, I'll see it drop to 7ish while flogging the engine: 65-70 mph at 4000 rpm going from 9,000 feet to 12,000 feet over the course of a couple miles. Going down the other side, coasting, it'll read anywhere from 50-90 mpg.

You'd think, based on those numbers, my combined average would be significantly biased to the higher numbers. But if my normal average is 13, a tank with mountain driving might be 15. 2 mpgs isn't much, but it is noticeable and it seems to be repeatable.

If my dad used to walk uphill both ways to school, why can't I drive downhill both ways to work?

yeah. I haven't been relying to much on my dashboards instant MPG readout. after I run a tank, or half a tank through and do the actual math I am realistically getting about 17.4 miles to a gallon. and that's with combined, driving nicely and driving like a real a-hole, some in town some freeway/mountain travel.

 

[ExplorerTom]

I always do the math too- or at least plug in the data to the Fuelly app and it does it for me.

 

[1955moose]

Guys our op hadn't stated whether 2 or 4 wheel drive. If 4 wheel drive, I doubt it, best is usually 12 city, 16 highway. 2 wheel will bump about 2 mpg avg. So 13 on a normal running no codes no rich motor. If he's got the smaller 4.6 two wheel drive and drives like your 80 year old granny, yeah he might be able to squeak out 17-18mpg. But he's not having any fun doing it.

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[blue oval guy]

Mileage claim might be a little optimistic