richiekie

Replaced MAF sensor per the CEL code. While I was at it, also replaced the plugs and air filter. Still running rough, idles rough, and at high speeds, seems the engine is not getting enough fuel. Put some techron in the tank , because it was running real rich with the old sensor. any ideas on what to do next. I was careful in following directions when replacing the MAF, although its hard to see if there is a solid fit with the air box and hose underneath. It sounded like it went in properly.
Thanks in advance for any help.

Rich

Jeff W

The engine may take a little while to adapt to the new MAF sensor. Mine took a few cycles to run properly after I cleaned my MAF sensor.

Glyn M Ruck

Hope you bought the genuine Bosch MAF for Benz. P/N is on the black plastic cover. Audi MAFS look identical but don't work.

Other possibilities:

Dirty injectors.
Oil in engine harness from front cam sensors.
O2 sensors.
Dirty throttle body.
Damaged throttle body actuator.
MAF not yet adapted.
Faulty coil pack.
Faulty or fouled cylinder head - common your year. Do a compression test.
Clogged or damaged fuel filter (includes fuel pressure regulator).
Lazy fuel pump. For filter & pump check fuel pressure on the injector rail.

Is the car storing any codes? - check with OBDII scanner

Good luck!

richiekie

Thanks for the replies and info. I bought the oem part from autohausaz.com. Its a new vdo/Siemens part. When I changed the plug in cylinder 4, there was oil on the old plug.

Glyn M Ruck

Oil on the threads?

Or oil here on the tip?

richiekie

hi Glyn,

Oil on the threads. By the way, the car seems to be running better, so maybe it is the MAF meter needing time for adjustment. How many miles does it usually take for complete adjustment? At lower speeds it runs okay, but at around 80 mph, it stalls out. I'm wondering if that's part of the adjustment process?

Anyway, thanks for everyone's help so far

Rich

cjennjr

When I changed my plugs last weekend, I found oil on the threads of plugs 1 and 2. What is this an indication of? Bad gaskets?

Glyn M Ruck

Oil on threads is nothing to worry about. Weeping gaskets or a spill.

In 100 miles ECU/MAF should be totally happy with one another.

richiekie

thanks Glyn

Cheers, Rich