Hey Guys,

I bought a 2001 a4 quattro 1.8T manual transmission, Chipped. Everything seemed to be in great condition. Once I bought it, immediately did the Tune Up, But there seemed to be a decrease on my MPG, Started off with like 21MPG and slowly went down to 19.5 or so for quite a while. Its been 2 weeks since its been decreasing like crazy, now im down to 15.5MPG!!!!
WATTA HECK? IS IT EVERY A4 LIKE THIS? ITS DRIVING ME NUTS, TOO MANY GUESSES...SPARK PLUGS, O2 SENSOR, FUEL PUMP, GAS FILTER??THOSE ARE MY GUESSES...
Any Help??

 

what about your guesses? did you actually change or swap anything?

you buy the car at 21MPG, you drive it and its at 15.5... ever consider your driving habits?

 

Just curious , did you change your oxygen sensors? Most people do not realize that they are probably the most important component in a tune up.
Also is your check engine light on? If not check for any pending codes. Could have a mass air flow or coolant temp sensor taking a dump. Is the coolant temp right in the middle? A engine running too cool will burn mor fuel.

 

^agreed with M5S5. That reminds me (CTM).

nice name by the way, i feel like i am almost in the twilight zone

 

Loorn: MMM no i have not swapped anything yet, I want to wait till I get a concrete answer and not spend unnecessary money. Sometimes I do drive a little abnormal, but mostly just drive around the city, but still, my friend has a GT and he gets like 23 or so stable city MPG. So im getting the miles a v12 would get. So thats just my big issue at the moment. Thanks!

M5S5: The previous owner said he has not modified anything, just chipped it and regular tune up. its at around 143K, so im guessing i'll probable need a new o2 sensor by now right?looks fine though, passed the smog test and all. It seemed to ahve statrted giving me the MPG problem after i did the tune up. Could be the spark plugs are not gapped correctly? I might have them gapped for a non chipped car, which is at 32''. No check Engine Light. and the temperature is always in the middle. never moves from there, unless the car is turned on in the mronings or after somehours.

 

BY THE WAY... I did put an aftermarket clutch and flywheel (F1), and thats when the MPG went downhill. Maybe the mechanics messed with something so I can go back to them?who knows nowadays.

 

is this 15mpg actually calculated? (take miles driven divide by gallons put in) Or is it what the little screen is telling you its getting? When you did the "Tune Up" what did you do? Even on a little k03 if you're boosting everywhere you go mpg will suffer. Do you have a boost gauge? No? get one. Vac leaks could be robbing mpgs too and don't always throw a code. A boost gauge that reads at least 25psi and -30in/hg vacuum is what most of us have/had.

 

Yes I have actually compared the Screen numbers and mine and its really accurate, now right after i switched the Clutch, the mpg are like going up and down while I drive. It is the stock turbo but I just met some other a4 who's getting 26MPG and its the same car and model. On the Tune up just regular stuff, Plugs, Air Filter, Oil..No i do not have one, I will look inot getting one of those then. But i Think 15 mpg is way too low for a 4 Cylinder vehicle.

 

Hard to believe you're getting 15 mpg and NO check engine lights whatsoever. I know this sounds like I'm treating you like a _______, but I might as well ask...

When you do your "mileage" calculation, I assume you:
1) Completely fill the car up
2) Zero out the trip counter or make note of the mileage
3) Drive until the car is almost empty
4) Fill up completely and make note of the amount of fuel you put in
5) Make note of the mileage or trip computer number
6) Take the number you got from step 5 and divide it by the number you got in step 4

So is this what you did to calculate your MPG?

 

I'm getting around 15 also but I have to change o2 sensors