94 E320 M104 Stalls unless MAF sensor is unplugged. What could this mean? SOLVED
 

I just bought my second M104 in an E320 wagon and as happy as I am to own a wagon (family of 7 in a few months so this keeps me driving a reliable old MB which I'm very happy about), I'm a little nervous that it will become a money pit.

Plug in the MAF sensor and it'll stumble, try to idle and kill. I happened to unplug the MAF and it actually runs! Enough to get me a 3 hours drive home thank God. I realize that this is called Limp mode (owned an E320 a few years ago). But anything else this means? I cleaned the MAF sensor with spray MAF cleaner and no change. I'm guessing that there could be other problems. Also the harness is original (looked and see a 1993 date). Not sure if the PO's mechanic changed the O2 sensor(s??). I checked the fuse on the OVP relay and it tested good. Haven't checked the relay itself. No CEL but the bulb may be gone who knows. Haven't had the chance to pull codes (have the Arthur Dalton code reader I built years back). I'm sure it'll give a MAF code since I drove with it unplugged. It doesn't feel like it's got an ignition/spark issue. Not really missing, just kills if the MAF is plugged in and definitely doesn't do low speeds well without stumbling and killing. But it halfway runs without the MAF plugged in. Just a low idle and surging if in park (limp mode). But much better than when I plug the MAF back in.

Thanks for any tips!!

My first guess would be bad MAF in need of replacement.

before you start throwing parts at it, replace the harness. a signal or 2 could be crossed and making it run bad. the more you move the harness, the worse it'll get. remember the harness that's part of the throttle body will rot inside the casing, so if the engine harness is 93, odds are the rest are original, also. good luck, chuck.

That's sort of what I was thinking. I'll be taking the harness out, cutting the wrap and inspecting before moving any further.

I just replaced my airflow sensor due to the exact same problem your having last wek, my 94e 320 s wagon was stalling , wouldnt stay running
unless i gased it , smelled light rotten eggs out exhaust at times, removed plug due to finally woulnt even run, limped it home , next day ordered a new new mass airflow sensor,installed it back to running perfect again

Check the seal (at the clamps) on the crossover pipe from the air cleaner to the MAF sensor to make sure it is tight. If it is not it will leak and a big leak will prevent the car from starting (my experience) so I assume a small leak will cause the problems you describe.

Changed the MAF Sensor and it idles great. Problem solved for now.

Welcome to plug n play.