I usually get 19 mixed.

 

If you're the type of driver that doesn't like to let other cars get ahead of you from a stop, you're not going to get good gas mileage. I've noticed with my car that there is a really big difference in mpg's between city and highway driving though. These 1.8 engines get thirsty when accelerating, compared to cruising on the freeway.

 

Okay so i was gonna go buy me the o2 sensor however the guy at ecs tuning says there's 2 in the car, front and rear. So which one should i replace when talking about bad gas mileage? Both, front? Thanks

 

Do you have VAG-COM or know someone who owns one? It could help to check the ECU for any engine faults related to O2 sensors, I know mine occasionally comes up with an O2 fault but doesn't show a CEL. You could also check the measuring blocks for the O2 sensors and determine if either of their readings are off.

 

The front O2 sensor checks the amount of oxygen or fuel left in the exhaust and tells the ECU to increase or decrease the amount of time that the fuel injectors stay open. The second O2 sensor checks the amount of oxygen or fuel left after the cat in order to see how efficient is your cat.
So, for bad gas mileage, the first O2 sensor should be replaced. Also a bad MAF can cause serious drops in gas mileage.

 

mine is a 98 2.8 Q, I get about 20-22. Seems like it should be getting better mileage. It is not running in top condition, but I'm work'n on that.

 

Ok i finally got my cheap vag cable from ebay and got it working. it found one fault and here it is.

17511 oxygen (lambda) sensor heating; b1 s1 performance too low
p1103-35-10--- intermittent
readiness 0000 0000

So which part is that exactly? Thanks again!

 

Just as I suspected, you have pre-cat a bad oxygen sensor. Replace it and you should get a better gas mileage. By the way, 20-22 mpg is on the highway or inside a crowded city?

 

Sadly 20-22 on highway... So pre cat would mean front o2 sensor right? Thanks for all the help.

 

You really have a low gas mileage. Yes, the pre-cat is the front one. I'm not sure but I think that you have to connect VAG-COM and clear all the codes after replacing the O2 sensor and you will notice the better gas mileage after a few tens of miles, after the ECU adjusts the learned values from the previous, bad, O2 sensor with the new ones from the good one.