Why does my W202 need a MAS

Discussion in 'Engine' started by JDP, Aug 12, 2006.

  1. JDP

    JDP New Member

    Aug 12, 2006
    I have had a problem with my W202 for a few weeks where in the morning, especially when it is cold it mis-fires a lot and there seems to be a complete lack of power until the car warms up. Having read some threads on MAS problems I disconnected the MAS unit (un-clipped it) and like magic the car seems to be transformed. No more mis-fires and performance is like it used to be before the problem started. If I reconnect the MAS the problem comes back. My question is, why should I replace the MAS unit? Can I simply not leave it disconnected. Can anyone help.
  2. Dieselman

    Dieselman Banned

    Jul 13, 2003
    Peugeot 403 Convertible
    The MAF (MAS) senses the amount of air being injested by the engine and alters the fuelling and timing to suit.
    With it disconnected the ECU adopts limp home mode and runs a pre set map which will err on the side of caution. Your car won't be delivering full power or economy without the MAF connected.

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