Troubleshooting MAF Sensor for '93 240

[marinman]

Hello,

My 1993 240 wagon with 239k has been idling quite rough, hesitating at slow engine speeds, and seems to be running rich at idle. While it hasn't thrown any codes, I'm leery of the MAF sensor (Bosch 0 986 280 101). The LH2.4 factory service manual only suggests a resistance range between pins 2 and 3 of 2.4-4.0 Ohms (I'm seeing 3 Ohms). My question is, should there be predictable voltage range across pins 1 and 3? Engine off, ignition on, I see ~1.5V. With the engine on at idle, it jumps to ~2.4V. No matter how hard/fast I rev the engine, the voltage never goes over 2.8V. Based on other MAF sensor specs, I would expect a wider range - however, I can find much about this particular beast. Anyone have experience with this one? I cleaned it today and it made no difference.

Thanks!

Joel