so ive done a little reading, and so far ive come up that maybe im a bit lean or something to the matter maybe a boost leak. but lately ive been getting poor mileage, barely or less than 300 on a tank, and my boost sometimes ramps up kinda funny. ill hit 5 psi for a second then stop at 15 then peak at 24 then settle at about 17. seems normal, but the weird thing is that it seems to jump instead of steadily climb, and my exhaust tips are jet black. i dont have any constant codes. the light pops on for a day or two then shuts off, hasnt been on for some time now though.

let me know what yall think

could be a dirty/dying MAF causing the bad gas mileage and wierd boost. Atleast those were the symptoms on my A4. I unplugged the MAF and took the car out for a spin and it drove a lot better. So its either my MAF or air leaking around the MAF. Could be a similar issue with your S4.

thanks for the tip man, ill check into it

That boost dosnt seem normal..... i would think it should sweep up to maybe 19 on GIAC hold a little below that, then taper off as you go towards redline.

I bet you have a boost leak. Start by pressure testing and finding what the codes are. Even if the CEL goes away your car saves the DTC, some CEL's automatically reset after XXX miles or shut off's

When it spikes to 24psi do you get throttle cut?


The black tips is carbon & fuel not that itsnt normal. Mine are allways black except right after i wash and clean em up.

But if you have a boost leak youll be running rich so there would be more unburnt fuel and maybe that would make it happen more

cool cool, ill do the pressure test, and i dont remember any throttle cut but i havnt been driving much lately, pretty swamped with classes so ill take her out and give it a try.

also i do have an apexi autotimer, what kind of readings would i get if i were running rich?

all right, had to go to work today so i did a little boosting, no problems everything normal. so the only question still remaining is the 277 miles on a tank of gas?

277 miles on a tank!!! your lucky, i get like 200 miles to a tank of gas because most of my driving is city. But on highway i get about 275 miles to empty on a tank so that seems normal to me. Im not talking about the driver information system but the tachometer. I reset it everytime i fill up.

i got gas today at about 1/3 tank of gas left maybe a little more and i was at 220 miles

yeah there is no way your getting over 300 miles to a full tank.

wow guys im sorry for your crummy mileage. i also reset everytime. i used to get like 350 but i guess that was before the chip( i figure keep it under boost and im good to go) but a lot of people say they still get about that with a chip. im about half and half city highway and hen i am in the city i tend to keep it running under 2k