cold weather im gettin 17-20 mpgs depending on how i drive, let the car idle in the mornings... i only had it for a week and a half before the cold set in and the snow came and i think i got about 21ish, would anything be worth buyin that might help me increase the mpgs? maybe intake etc.? 03 a4 6 spd quattro

 

1.8t or 3.0 ?

 

woops sorry... 3.0

 

As long as it's cold out and the fuel blends are crappy, there's not much you can do, but a seafoam treatment sure wouldn't hurt.

 

True enough. Also, do you have service records for the car? If so, when was the last time the O2 sensors were changed? They'll have a bigger impact than anything else on fuel economy. Double-check tire pressures too - in the cold, your pressure will drop and add rolling resistance, which can hurt mileage more than you might think. Also, at least on the B5s, the coolant temp sensor (CTS) is a pain in the *** and it can have quite an impact on mileage as well. I'd check all of that out, and maybe clean up as many electrical connectors as you can (with electrical contact cleaner from Radio Shack) - particularly, hit the O2 sensor connectors, MAF, CTS (if it's accessible on that engine), check your air filter, check spark plugs (and regap or replace as needed). Individually, you may or may not see much from any of those, but do all of it and you could see a nice bump, depending on how far out of whack things are already.

 

Does that go for the post-cat o2 sensor?

 

I suppose it could but not in the same way as the pre-cat O2. The pre-cat O2 sensor is the primary sensor, which measures the oxygen content of the exhaust gases to determine the air/fuel mixture and adjust the fueling accordingly. The secondary, post-cat O2 sensor, is there to monitor cat efficiency and function. Basically readings are taken from both, and the primary sensor is used to determine fueling (along with CTS and MAF readings and a variety of other factors). The value from the primary is also used and compared to that of the secondary to determine how well the cat is working at scrubbing the exhaust gases. If the secondary was out of whack, the car might determine that the cat is not working right and trim the fuel accordingly. I think it'd probably enrich the mixture somewhat since a lean-burn situation in the engine creates (to the best of my recollection) more NOx (oxides of nitrogen) particulate pollution. By enriching the mixture this way, the car can take some of the burden off the cat. If that's the case, that richening of the mixture could be contributing to your crappy gas mileage. I'm pretty sure that's the way it trims but if someone else knows differently for sure, please chime in and correct me.

 

Oooo if you do have bad front O2 sensors...............I would rather beat my teeth in with a sledge hammer then change those on a 3.0L. Those suck. [:'(]

Got any fault codes? That, and if you have a VAG COM check the OBDII data and look at the live CTS data and look for any wierd temps, like -50 or something dumb like that.

 

LOL, that's encouraging. But yeah I bet they're a pain - I've seen underhood on a 3.0 and it doesn't look like a lot of fun to get at them.

 

haha thanks guys... it doesnt look like alot of fun under there no, but when do the o2 sensors normally start going bad? because thats still under the factory warranty from audi 8 year emissions i do believe... and do you guys think that my gas milage is bad? i didnt really think it was that bad considering the weather and the fact its quattro 3.0... but hey im always open to better feul economy