Horrible , horrible MPG! - advice please!!!

[DonnieDark0]

would any of this contribute to getting 13 mpg?

2000 s4 6 speed stg 2 + 114k ( perfect psi in tires :) )

giac chip 16 psi
manual boost controller
SSAC full exhaust ( downpipes, test pipes)
leaky valve cover gasket / cam seals ( replacing this weekend )

CEL codes =
both post cat o2's not hooked up, throwing CEL.
n75 and n249 delete, both throwing CEL.



was going to get a custom tune and CODE those 4 codes out of the system in the spring when I got stg 3.....


Now my question is, before I get it custom tuned and coded out, are those CEL's giving me this horrible MPG? so will the problem go away when I get them deleted?

if not , then where the hell do I start? ( spark plugs?, gaskets? tune?)

thank you so much in advance. Just curious on if the answer if right in front of me cause of my current issues.

=D

[seanj130]

up stream o2? primary o2 sensor is what did it for me.

[RolledMySTi]

Primary O2's would be my guess as well.

[ThePeoplesChamp]

and you're also running 19lbs when you ecu is requesting 16 haha

[DonnieDark0]

and you're also running 19lbs when you ecu is requesting 16 haha

hahah, listen buddy!!! , i turned that sucka down to 16!! so dont give me that blasphemy! lol

[sturat_7]

up stream o2? primary o2 sensor is what did it for me.

either this or running 16 lbs is killing you. If its not those go with spark plugs and work from there, mpg is most likely related to O2 IMO.

[Dimcorner]

I'm guessing main O2 as well... I'm getting close to 22mpg with about 30% hwy time only.

[DRA4]

I am getting like 14mpg but no codes for any 02 sensors

[skinnytirez]

I think the biggest contributor to your shitty gas mileage is your right foot lol
My right foot likes to give me less than 10mpg as well, but that gets expensive real fast lol
Driving to my parents house from college one day on a back highway (50mph speed limit) resulted in this MPG average...

on the very same trip (very fun as there are lots of tight turns) with a heavy right foot results in 10-12MPG

...just my .02$

[KNaudi]

^^ you do know the computer is massively optimistic, right? I can play that game too... I actually got 370 miles on this tank (which is fantastic for me) but the computer was telling me this:



plus your pic is just of the "at the moment" economy which is easy to manipulate.

[skinnytirez]

i know it's optimistic...but it has to be somewhat close over a 24mile drive; and that's the average, not the instant

[DonnieDark0]

either this or running 16 lbs is killing you. If its not those go with spark plugs and work from there, mpg is most likely related to O2 IMO.

Thank you! this weekend I will do the spark plugs along with the gaskets and go from there. then if it doesnt get better I will replace both upstream o2's.



EDIT: cant blame my heavy foot cause I calculated this without going into boost AT ALL , monday-> friday ALL highway miles. no city.

still 13mpg. and im not using the computer generated MPG because my pixels are 99% gone.

[crashalot]

Yeah, sounds like o2's the engine is protecting itself.

[DxC]

i know it's optimistic...but it has to be somewhat close over a 24mile drive; and that's the average, not the instant

no thats the instantaneous, not the avg. the avg has a phi symbol

[Fourplay]

^^ you do know the computer is massively optimistic, right? I can play that game too... I actually got 370 miles on this tank (which is fantastic for me) but the computer was telling me this:



plus your pic is just of the "at the moment" economy which is easy to manipulate.

Mine has read 595 miles a few times, it's super inaccurate, as is the actual fuel gauge. The first half of the gauge I can go 200-210 miles, but the 2nd half is between 100-130 miles. The best I've ever gotten on a tank was like 342 miles on 14.5 gallons.

[TipTucker01]

^ Mine has the same problem. Do you know of a solution for it?

[Dimcorner]

^ Mine has the same problem. Do you know of a solution for it?

Get gas before the car stops dead?

Most I have ever gotten out of a tank was right at 400 miles with a 14.7 gal fill up. Last leg of the Boston to Ft. Lauderdale return trip.