The 99-00 are extremely rich. 01-02 are leaner and 03-04 leaner again.

If you want a cost effective fix, buy an 03-04 computer from the junk yard and a 90mm MAF and you will see a substantial difference especially with the 3.55 gears. You will also gain over 25hp in the process with a safe factory tune. Just keep in mind that speedometer error will be 8% on the low side or 5mph at 60mph.

TB

 

Hey thanks for the info. I actually put a tune on that came with the diablosport tuner and the mpg seem to be a little better, but I do still need to upgrade to the 90mm maf.

 

Hmmm, I average 14 mpg on my 99'.

 

good idea - however trying to find an 03/04 Lightning from a junkyard is (I suspect!!) going to be quite a thankless task... unless of course all you peeps out there know better

 

Do a search on carparts.com. Eventually one will show up. 03-04 is very similar. That's what I did and got one for $150. Always a bunch getting wrecked by the 20 something, eager to re-live their favourite scenes from the Fast and Furious...

 

Well I was talking to a buddy of mine who owns his own shop and I told him about my crappy gas mileage. He said that during the winter here in Iowa (the temp hasn't been over freezing in a few weeks) you will get worse gas mileage because the computer is reading the outside air temp, so it is sending all that extra fuel to help it get warmed up. It makes since especially since all of my driving is only a few miles each way so the engine doesn't always warm up completely. So hopefully that is all it is and I will wait and see if it gets better in the coming months.

 

Same for me...city! Between 13 and 15 combination city/ highway!

 

The 99/00 Lightning's generally see about 10.5 to 1 A/F which is rich. A good tune on that truck would be a bebefit to you and should increase your fuel economy to about 13MPG. A CAI would also help.