My '99 has the same issue with the fuel gauge. It's has been that way from the beginning.
I'm curious which tune you uploaded? I went thru all three and settled on the economy because it seemed to work great between power and shifting.
I haven't checked my mileage yet either but, like you, the gas gauge seems to move a little slower than before. It generally moves like a second hand on a clock. LOL!
I'm going to drive it to Greenville, NC (ECU) this weekend and I'll get some good mpg stats.

 

The gas gauge circuitry uses a moving-average sort of thing.

If it sees the float going up and down between two extremes, it tries to average that.

If, once it's got an average, you move it so that the float sits lower, it'll average the previous average and the new level. And vice-versa.

if you cycle the key, it SHOULD read the correct current level, but I think there's a delay built into it for that. If you notice when the low-fuel light first comes on, it stays on until you cycle the key.

 

I'm running the 5-Star 89 performance tune.<O</O
The gas gauge is defiantly moving slower then before. By 150 miles I would have been down around half a tank or less by now. I think Ford made it so that the gauge wouldn’t go back up quickly to prevent the needle from moving so much as the gas sloshes around in the tank. I'll have to leave the key on when I fill it and see how long it takes to detect the full tank.
My trip to<?xml:namespace prefix = st1 ns = "urn:schemas-microsoft-comWisconsin</ST1</st1:State> should be about 4700 miles round trip.

 

Hey Art,
Ya that's what I see. If I turn off the key sitting on level ground it comes up to a more acurate level. If I am doing some driving that sloshes the tank a lot it will read lower until I turn the key off again.

 

Have you tried the economy tune yet?

 

No I didn't get the econo tune. I didn't buy the truck for economy. I just got the performance and the tow. Mike recomended the tow for off road driving. I actually hadn't planned on even getting the tuner until I did a rebuild but after reading about what everyone was saying about it and a plug in power and fuel mileage improvment without making a bunch of mods to the truck sounded pretty good. So far it's been good.

 

I didn't realize you could get the 5star Tuner with just the performance and tow tune.
Anyway, I can't tell the difference in power between the perf. and econ. just shifts smoother.

I'd love to hear what others say about it regarding the '99 model.

 

I picked my tuner up used then just contacted Mike about the tunes. They sell them one, two ,or three. The price per is better the more you buy. The most is three. You just got to make sure the unit you get is unlocked or unpaired. It locks to your vehical once you load the new tune. To unlock it you have to reinstall the factory program you took out. It cost something like $150.00 to have SCT unlock it if let say the orignal vehical got distroyed so they sold the tuner.

 

The Xcal2 and 3 can only store 3 custom tunes at a time BUT that does not mean you cannot get more than 3 tunes. You can have 100 different tunes on your PC and upload them to your Xcal.(Only 3 at a time) All the tunes I have are the tow tunes and performance tunes. Mike basically told me I wouldn't like the economy tune for what I'm after. Also I would recommend saving a copy of your Stock tune to your PC as well as backing up the tunes stored in the Xcal.

 

Gotcha.
Yea, I can see where the tow tune would be good off roading or pulling a heavy trailer/camper. I have a 29' toy hauler that I have always pulled with a 6.0 psd. Due to the economy last few years we got rid of it. I'm going to have to pull it with the V-10 now. I'm curious as to how it will do.

 

That's true you can have as many as you want the unit will only hold 3. Thanks for the heads up on saving my OEM. Haddn't though of that. I've got my tunes backed up already. My computer does that automatically as soon as I downloaded them. So is that what the 5 unlocks are for. So you can do more then one vehical if you have more then one? Could I use it to program my Mustang (if I had one) with a tune for that?

Let me know how that tow goes. I don't plan on pulling anything big with it but it does already have a gooseneck in the bed just in case.

 

Yes, absolutely backup your tunes. Save them on a flash drive, just to be safe.

Better yet, burn them to CD or DVD

Talk to Mike directly, he is very accommodating

 

I drove it round trip 500 miles this weekend no trailer and got 12.2 mpg on economy tune. I have seen better on this truck w/o a programmer but not much, 13.1. I was hoping to get at least 13 with the economy tune. There may be other causes. Felt like it was missing a little on up hill pulls. I'll check codes tomorrow.

 

Okay, so while I didn't give myself a lot of untuner time I figured I was getting about 7-8 around town. This tank I ran 21 gal and got 188 miles. That's almost 9 (8.9). Mind you that all just to and from work, less then 10 miles each way and local runs to the store. If I drove a little easier I could have gotten it over 9 but I don't drive with a very light foot. It will be interesting to see how the freeway does. I always do well on freeway becauseI like to use cruse control. Keeps me from getting a ticket. That dam heavy foot problem.

 

You might want to load an economy tune for that trip because you are talking a lot of gas $.

If the tow or performance tune nets 13 MPG = 361.5 gallons
If the economy tune nets 15 MPG = 313.3 gallons
That savings of 48 gallons = ~ $200 in gas.

That 13 MPG and 15 MPG is just an example, but you get the idea. You could save a couple hundred bucks by using the economy tune for that trip.