As an update to this , since initially resetting the fault codes the aftermarket MAF has given no further trouble ( although there was a fault code there from the original one ) .
Unfortunately , the P0660 code returns every second or third day , with the car dropping back into limp mode . I presume this is the much discussed swirl flap problem .
Since the car remains mobile , albeit with a loss of performance , and the fault is easily reset , I will soldier on with it until the Christmas holidays when I can work on it .
I've read the various threads on this and other fora about removing the flaps and plugging the holes ( and can do this during the holidays if need be ) , but speaking to DRUK on the phone the other night , he suggested cleaning everything up and putting them back in again . I still need to look on EPC and see if the flaps etc can be bought separately from the manifold , as I know the whole assembly is £££ . Since I'd be doing the job myself I don't mind spending time on it , as opposed to money .
I had the manifold off the W124 E250D when I did the glow plugs and it was straightforward enough ; the 270 engine looks broadly similar .
While I'm about it , I also need to change the thermostat and the block heater , and , if having the manifold off helps , perhaps might be as well to do the glow plugs at the same time ... since all these things are in the same area it kind of makes sense to do them all at once .
No doubt once I get in there I'll find other things that need doing .
they probably won't be applicable to Mercedes cars post a 2007/8 date of manufacture. 
which may be out of date of course??
