W140 300 SEL air flow sensor - PeachParts Mercedes-Benz Forum

lester · #1 01-08-2007, 07:34 AM

I have a 1992 300SEL type W140 with a 3.2 engine, it does not seem to have an air flow sensor like my other 1995 w140. Can anyone tell me why it doesn't have one. It is not starting very well and the spark plugs show that it is running rich, I was told by a merc specialist that it would be the mass air flow sensor. Also will this year model have fault codes stored and does it have what people call "limp mode"
Any help wuold be much appreciated.

Lester.

wbrian63 · #2 01-08-2007, 07:46 AM

Unless you're overseas (and I'm not even sure about that) your car is a 300SE, not SEL. The 300 wasn't available in a long-wheelbase here in the US in '92. I've got one myself.

The mass airflow sensor is the tube that sits atop the electronic throttle actuator under the air cleaner. It's black, about 3" in diameter and 4 or so inches long.

I believe it does have limp-home mode, and I'm sure it does store trouble codes. By the passenger side hood hinge you'll see a rectangular black cover with a round cap at the forward-most edge. Beneath that cap is the X11 (I think that's the number) connector where you can pull DTC's for all of the car's various systems. I believe DTC's for a faulty mass airflow sensor would be stored in the LH module.

You can build your own (or purchase from various sources on e-bay) a impulse counter tool to allow you to pull your own codes. There are 3 wires, one for 12v+, one for ground and one that plugs into the proper port for the system you want to pull codes for. It's easy as pie to pull codes - suggest a membership to AllDataDIY.COM for $20/year to give you access to all the codes these beasties can throw.

mbdoc · #3 01-08-2007, 08:03 AM

The fuel system will generate codes...also with a HIGH-end scanner it will support LIVE data..also the ignition & electronic accelerator.

pcmaher · #4 01-08-2007, 10:03 PM

Quote:

Originally Posted by wbrian63

You can build your own (or purchase from various sources on e-bay) a impulse counter tool to allow you to pull your own codes. There are 3 wires, one for 12v+, one for ground and one that plugs into the proper port for the system you want to pull codes for. It's easy as pie to pull codes - suggest a membership to AllDataDIY.COM for $20/year to give you access to all the codes these beasties can throw.

http://www.v12uberalles.com/pulling_codes.htm