[Velocity211]

So, when I started to daily drive my NA-T, I noticed something very, very out of the ordinary, it was getting about 200 miles to a tank, which I figured is about 11MPG... I absolutely don't boost it and shift at around 2.5-3k RPM, every five minutes I look down at the fuel gauge it goes down a notch. A couple of guys on clubna-t recommended that I get the car tuned, I did, turns out it was running on such a terrible tune my engine could've popped any second I drove it any more.
Dropped $200, car now runs lean like how I like it (15-16 at cruise). Next refill, I looked at my trip gauge... I've gone 225 miles.. what else could be causing this horrendous mileage?

XSPower T61
525cc, Walbro Fuel Pump
HKS DLI
AEM EMS

 

[1sxyrxy]

replace plugs, do you do alot of street driving, whats your AFR under light accel and starting form a stop.

 

[Velocity211]

From a red light, I'd have to say around 13-14, light acceleration is around stoich.
I'll replace the plugs next time I change my oil, any brands you guys recommend?

 

[Boosted Rooster]

From a red light, I'd have to say around 13-14, light acceleration is around stoich.
I'll replace the plugs next time I change my oil, any brands you guys recommend?

i hear about alot of guys using ngk or denso...the iridium ones if you dont mind spending the extra $$$...i use regular ngk's myself, but im not really in any position to recommend them, my car has some crappy mileage too

 

[LastDrift]

For na-t cars I'd recommend NGK3330 or 6097 gapped at .028

 

[1sxyrxy]

i dont remember what i ran on my NA-T setup. you could run a little leaner on take off and light accel. dont know how much it will help. clubna-t.com has some help also

 

[Sleepr]

I get around 18mpg around town, generally shifting around 2.5-3k rpm. Run AFRs close to stoich on the stock W58 5spd. Lost probably 2 mpg with Crower cams, lost mpg with 285s out back. With the AEM, there is no reason you couldn't run 16:1 or 17:1 under light throttle, with good timing advance. That 18MPG is suburban driving - i.e. most speed limits at 35mph, a few stop signs, a few stop lights, but not downtown with a light every 1/8 mile.

I want better MPG and often thought about switching back to stock cams and running the AEM so that I can run leaner and more advanced more often. Also thought about the Auto TT LSD to get a little taller ratio.

the 3330 plugs are awesome if you want to change them every year. Denso Iridiums may not make the biggest power, but they sure do last.

I was going to mention the MSD 6BTM, but i see you already have the HKS DLI. The MSD box fires the plugs twice at low rpm. Changed the idle and perhaps increased the mpg a titch.

Oh, perhaps the biggest mpg adder: stock compression ;-) 8.5:1 doesn't do wonders for efficiency.

 

[Memphis]

My mpg is around 12-13. I have basically the same setup as the OP. I don't push it very often, maybe a few pulls every now and then. I think gas mileage really suffers on the highway, if you're 5spd like me. Sitting at ~3.8k the whole time you can pretty much watch the meter drop.

 

[twinturbosupra94]

My mpg is around 12-13. I have basically the same setup as the OP. I don't push it very often, maybe a few pulls every now and then. I think gas mileage really suffers on the highway, if you're 5spd like me. Sitting at ~3.8k the whole time you can pretty much watch the meter drop.

Yeah...W58 gearing is not exactly the best for highway.

 

[TRDmonkey]

Yeah, gas mileage with the w58 isn't all that great. What do you gap your 3330's at?

 

[Velocity211]

I'm gonna mess with my AFRs this weekend some more, go as lean as I can before the knocking and misfiring occurs
Yeah I'm sick of the stupid W58 rear, stop and go traffic wouldn't be as unbearable if 1st gear at 10 miles an hour wouldn't stay at 4k with my loud ass ricer exhaust droning out any sense of peace left in me.

 

[Ravan17]

i can get 200 miles on a tank driving my car hard..... with that said, i dont really avrg more than 220-230 miles per tank

im sure the car could get a lot more, and even when i boost only 7-8 psi in each gear from stop lights....i forget to realize how much more fuel it takes to make the power over a factory NA set up b/c at 16psi (top boost i run daily) i am making almost 3 times the power of an NA car. but anyways, i can get better milage... i just dont try hard enough

 

[Boosted Rooster]

i kno for a fact i can get better mileage than i do, if i had a better tune that is

 

[vreaux728645]

Yeah...W58 gearing is not exactly the best for highway.

I'd say the 4:27 rear is to blame. I got a bit over 30 mpg with my 3:73 mkii on the highway turning ~2250 rpm @ 60-65 mph.