FI tuning

[robfajita]

I have a 99 Tacoma TRD SR5 V6. My check engine light came on a while ago. I had a friend pull the code from the ECU. It comes up as PO172, which is "too rich" according to "troublecodes.com"

So heres my question: How do you lean out an EFI system? I thought the computer was supposed to do this automatically.

Oh, and I live in Colorado at about 9000 feet above sea level. Wht do I do?

[4xfred]

;D You're right. You can't change the factory settings. Sounds to me like you have a problem. My 1st guess would be press. regulator. Pull the vac. line & see if it's wet inside. Let us know. Later...

[BurntOrngeLonghorn]

My first guess would be the Mass Airflow Sensor......I would try cleaning that.....it's simple to do, and if your rig is to rich or to lean, it has to do with air/fuel mixture....so that would be my first guess. Dirty sensors don't give correct measurements.