q45 fuel mileage

[qship96]

well,after averaging 16mpg during these cold months,it was refreshing to get 22.58 mpg today on a round trip to the shore,total trip was 319 miles,light traffic,and kept below the 2499 rpm fuel enrichment mode! guess all is still well at 128,000 miles on the q!FYI- used sunoco 94 oxygenated fuel as usual.

[AZhitman]

I'm STILL lucky to get 220 miles per tank.

New O2's on the way.

[elwesso]

Ouch...

I just got about 20ishmpg on a highway trip where 75-80 was average cruising speed, with many bursts up above that......

[Q45tech]

They get what the EPA says 22/16 under each appropriate driving cycle with conventional gasoline and 5-10% less with oxygenated............assuming alignment [camber toe] and tires have oem rolling resistance at 35 psi.

A totally frozen locked up O2 sensor can only make it 20% [usually only 10%] worse.

[areznik]

How can I check whether my O2 sensors are good or not?

Thanks.

[Q45tech]

Connect the Consult and measure the cross over counts [how many times per minute the o2 voltages switch from rich to lean] at a steady 2,000 rpm.Most lambda sensors will cycle from rich to lean in about 50 to 100 milliseconds, and from lean to rich in 75 to 150 milliseconds. This is referred to as the "transition" time. If the O2 sensor is taking significantly longer to reverse readings, this too is an indication that it is getting sluggish and may need to be replaced.

http://www.picotech.com/auto/lambda_sensor.html

Pretty much if a 02 sensor has 100k on it it is always sluggish!

[elwesso]

Dennis.... What would you say the average service life of an o2 sensor is... Ive heard 60k before??

[Q45tech]

On the Q it Depends on gasoline quality. Plus how vigorously you blow the carbon out of the system weekly

The only detailed precise experience is changing mine twice at 120k each.

I guess if the annual mileage was lower than my 20,000 miles, one might revert to 6 years which might be 60,000 miles life or 90,000 miles.

The newer designs after 2000 seem to fail much earlier and more frequently but they yield more precise wider band control.

I try to check the cross counts every 6 months after 4 years and make a decision.

[elwesso]

So if I've had good indiana gas and redline it nearly daily then they've probably had a longer life than most..

When checking them via the OBD thing, what would you say is the acceptable blink rate of the CEL??? Or is that method an innaccurate way to measure it...?