w202 - Running Rough

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New Member
Sep 19, 2008
First of all thanku to everyone who assisted me....

My car finally starts with a new key, however Mechanic states that it is running rough even when he revs it makes a poping noise and it doesnt accelrate. It has been parked for a month never had a problem like this before...He thinks its some air pump... any ideas.... Please.. Or is he trying to make more money out of me...
It sounds like MAF sensor..

Mass Air Flow sensor.. works out how much air is coming into the car and works with the ECU to control the amount of fuel going into the engine..

If faultly the car will run poorly.. over or underfuelling and generally very poor running.. bad or no idle.
Have you tried unplugging the MAF sensor first to see if it improves?
A popping noise can be indicative of excess unburnt fuel in the exhaust. Some cars have an air pump which injects air into the exhaust to burn up this access fuel under certain running conditions e.g. on the overrun. It's part of the emissions control system in some cars in some parts of the world but I am unfamiliar with it on your car. Your mechanic could be correct but there are many other reasons why your fuel/air mixture is not correct. Ranging from the ECU to the lambda sensor to the inlet MAF to the engine temperature sensor. You need to get the engine fault codes read to see what's causing the problem.
How do I disconnect the MAF sensor, and if i was to get a new one how much do they usually cost i.e Part + Labour. My car has been parked up for a while and during this time i have tried numerous time s to start it.. can this cause the fuel overflow. Thanks
Don't recognise the description- might be the crankshaft position sensor? Normally if they go faulty the engine just dies.
Might they mean the MAS Graeme ?

As RPM increases so will airflow , so perhaps they mean this ?
it is not the crankshaft sensor. the car will not start if it is this.
the maf sits on top in between the air filter and the engine intake.A black plastic culinder with a plug on top of it.
Might they mean the MAS Graeme ?

As RPM increases so will airflow , so perhaps they mean this ?

Don't think so Howard but who knows? Other possibility is the camshaft position sensor or the throttle plate position sensor??:confused:
hey guys...

Thanks it was the MAF sensor.... But one more problem... car was working f9 and the alarm went of the other day and now the central locking does not work... any ideas.. thank u for ur help so far
Try disconnecting the battery or alarm to reset it.
Boy, I bet you are glad you joined this forum:D

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