Hi,

My 1997 4.6L F150 with 75k miles has been getting progressively worse gas mileage over the last year or so. I have cleaned the MAF but am still running the original spark plugs. I got out my SCT Xcal 2 tool to do some datalogging. I did two sessions, the first is just letting the truck sit at idle from cold to full operating temperature while datalogging the O2 sensors. The second is starting the truck from warm and datalogging the O2 sensors as well as the long and short term fuel trim numbers at ~2,000rpm for 15 seconds and then at idle for a couple of minutes.

It looks to me that the O2 sensors are taking about 1.2 seconds to cycle at 2,000 rpm and something closer to 2 seconds to cycle at idle. From what I understand, 1 second is considered the longest for a cycle.

http://www.autodiagnosticsandpublish...or-testing.htm

If anyone would mind taking a look at the two CSV files from the datalogging sessions and weigh in, I'd appreciate it! These files can be directly read into the SCT LiveLink software.

http://dl.dropbox.com/u/11232328/f150datalog1.csv

http://dl.dropbox.com/u/11232328/f150datalog2.csv

Thanks,
Chad