Xixal, mine is 1996 C220 WDB2020222F385849 Auto Sedan. I hear you re possibly not the air mass sensor (silerarrow, I have not yet bought a new one, still on the original), but given the age, you'd advise me getting a spare air mass sensor right? This 8 yr old component is bound to give up ... and since the benz dealer here quoted me AUD$1600 for the part (!!!he must have got it wrong!? perhaps including labour??) I better get my hands on one whilst in UK. Right, since you mentioned cleaning the pins of the sensor, I am going to try to pen down what (cryptic) my mech detailed/performed for the service he did since the erratic idling reared its ugly head.
He said the diagnostic output these:
MB010 hot film air mass sensor 77935 open circuit
MB036 fuel adaptation (lamda) control mixture too rich (lean stop)
MB007 idle speed control (malfunction) cause by MAF
MB032 knock sensor (KS) defective cause by wiring
He had the car for 4 days but I suspect he wasnt working on mine exclusively! He performed lots of scans, diagnostics and testing and cleaning all the sensors/wiring/terminals. I remembered he specifically said he did clean the air mass sensor foil. No parts were replaced, he mainly tried best to clean, reset the ECU and by process of elimination/tweaking got the idling under control. He only charged me GBP100. However he has one warning note that the auto kick-down cable needs to be replaced - the adjuster is broken. Does this ring a bell and should I be getting this part too, what is it? You talked about throttle actuator - is this about the same thing? All sounding awfully similar to me. What should I do? He said it isn't all perfect as he was worried it might be the almighty Idle Speed Control 'Actuator' which he says contains loads of other units within that may be at fault and need replacing - do you know this part? Its $$$ according to him and the failure may be in it. I told him I'm off to UK and said parts may be cheaper so he said to get the:
- air mass sensor
- idle speed control actuator (he alerted it had many devices within that may have failed but always replaced as a whole pack)
- spare radiator! (yep mine has a leak at the neck of the sensor and that radiator part in australian models is different!)
He tuned it so much when I got back the car I could hardly hear the engine from within the cabin. It now idles just above 500. However these are the outstanding issues we both noted:
- when in Drive and idling and I switch ON the aircon it places a load on the engine and rpm drops sharply below 500 and usually car shudders heavily as it tries to stay alive. In Neutral or Park no shuddering cos engine not under the same load as Drive. FYI in Feb 2005 I got aircon specialist to overhaul the whole aircon system with a refurbished condensor/compressor - a full job (GBP640!) done on the car.
- when I have driven about 20 - 30 minutes (and never sooner), stopping at lights I am aware the idling mucks around and dropping below 500 either causes the ECU to compensate and up revs the engine OR engine cuts out altogether. No prob starting if it does (so far).
- there is a occasional and slight, very temporary loss of power as I accelerate from standing still
Any engine gurus please shed light.
