mpg improvements
#11
01-08-2008, 10:53 PM
RE: mpg improvements
ORIGINAL: CoBra03TerminAtoR
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
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
#14
01-11-2008, 05:50 PM
RE: mpg improvements
ORIGINAL: UpstateNYA4
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.
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.
I ask because I keep getting a code (from vag - not a cel though) for my rear O2 sensor. Additionally, I don't think I'm getting the best of gas mileage, so I'm wondering if that's the problem.
#15
01-11-2008, 08:04 PM
RE: mpg improvements
21 sounds just about perfect for a 3.0 and quattro... i saw a pretty good increase after i addedan intake and even better in the spring... it all went to hell after installing my test pipe and nowi wanna run into a knife every time i fill up...
