2001 Toyota Corolla MAF Sensor Feedback

Engine Performance problem
2001 Toyota Corolla 4 cyl Front Wheel Drive Automatic

I have a 2001 Corolla (recently purchased).

The P171 code came on and I searched the forums and decided to clean the MAF.

I used car chip to plot the feedback from the intake air temperature and intake air flow rate. I took the car on the highway, set the cruise control for 55 and drove it for five minutes. Then I took it home, downloaded the data to my computer and plotted it. The temperature is steady for the duration of the highway time but the intake air flow rate is all over the place. I thought, aha, the sensor is dirty. So I took it off, cleaned it with CRC MAF cleaner and I could notice a clear change in color. I put the sensor back on, took it back on the highway and plotted the results.

I got the exact same results, the intake air flow reading is all over the place despite a constant speed on relatively flat highway.

So my question is, is the MAF readings bad, or is this the type of feedback you would expect to see from the MAF. I could understand the readings from the O2 sensor changing but you would think that the air flow would be relatively constant. I don't see how any control system can react to what appears to be an almost random event generator. I have attached the air flow chart but I can email the plots (speed, o2, etc) to anyone interested.

Any thoughts would be greatly appreciated.

Thanks
Tom
[img:73bd0e00c2]http://www.2carpros.com/forum/automotive_pictures/581983_CarChipPlotAirFlowRate201010101403To1428_2.jpg[/img:73bd0e00c2]