97 2.3L running lean

[G-Man]

The check engine light came on in my 97 Ranger. Ran the diagnostics on it and the code indicates it's running lean. The oxygen sensors are original on the truck, (it only has 74K on it). Any guesses as to troubleshoot to why it's running lean? I'm guessing the oxygen sensor but just want to hear from the peanut gallery as to what else may be the cause for it to run lean. The air flow sensor was just replaced two weeks ago.

 

[G-Man]

Bump! Anyone have a response?

 

[ltbenji]

Vacuum leak is where I would start. Check for cracked rubber vacuum lines and/or loose fittings

 

[scotts90ranger]

Are you getting abnormally low gas mileage? If the MAF is dirty, it won't be seeing enough air thus giving it less fuel than necessary leaving the O2 sensor to do the work of moving the fueling up and causing that code.

Another possibility is a fairly significant air leak after the MAF

Yet another possibility would be an exhaust leak before the first oxygen sensor.

Get yourself a can of MAF cleaner and check that first as it wouldn't hurt either way, and while you are cleaning the MAF inspect the vacuum lines and intake ducting after the MAF.