Hi all,

Just wanted to post up a thread after going through my newly purchased car to work out what needed servicing and the general condition. One of the things I checked was the air filter which seems to be fairly fresh although not 100% new.

I then noticed that the grill of the MAF was very dirty so decided to pull out the MAF tube and check everything over. To my amazement the mesh was probably around 50% clogged with dirt and dust that would have stuck to it owing to the crankcase oil being sucked into the inlet just after it.

I then pulled the MAF sensor out (just 2 screws) but I could tell its never been removed or cleaned. I found that the sensor was badly clogged with all sorts of dirt which had stuck to it.

This would mean that the engine only thought that there was far less air than there actually was being drawn into the engine. I cleaned the MAF tube and tried to clean up as much muck as I could off the MAF sensor but decided to get another one.

I have reinstalled the MAF and put the sensor back in temporarily to keep everything airtight but didn't plug the MAF back in. Started the car up and went for a drive - massive improvement! Because the engine couldn't use the (incorrect) MAF reading it would go onto a fixed map of values, not that good for fuel economy etc but will actually be much better than a bad MAF reading.

On Saturday morning when I started the car up for a run around I found it coughed a bit and didn't feel like it was running very well, this then cleared up after everything was gently revved a few times. I was thinking that the glowplugs might be on their last legs and was just in the process of checking what I needed to order as well as a few other bits.

On Sunday morning (with the MAF sensor unplugged) I turned the key, waited for the glowplug light to go out and tried to start the car. It immediately and smoothly started up without any hesitation at all.

My car was on 230k miles, which I know is highish mileage, but I think that MAF sensor has been rather mucky for a fair while and could have been one of the reasons the car was for sale.

Anyway, just a 'public service announcement', next time you have a spare minute just unplug the MAF and see if it makes any difference, if it does I would recommend cleaning the MAF (usually with electrical contact cleaner). I would also check the mesh in front of the sensor which was very restrictive on mine.

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UK spec Mercedes W210 E300 Turbodiesel wagon - OM606.962 with 722.6 transmission - rust free!