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    Alfa 146 1.8 T-spark 1999 M1.5.5 ecu Archived Message

    Posted by Shaun Dale on April 1, 2008, 8:32 am

    Failed MOT on emissions.
    CO at idle is 0.15% and the lambda is within limits but on the fast idle test the CO is variable from 0.2 to 0.71% (ish) and the lambda varies but tends to be around the 1.04 mark, the HC's are also quite high in the 200-300 ppm region. It is also quite difficult to hold a stable 2500 rpm as the engine seems to keep cutting briefly (not a misfire as such but a complete cut as if the engine management thinks the engine is over-revving at idle and is trying to stop it by cutting the spark and injection).
    Driveability is fine you would not think there is anything wrong.
    The Lambda sensor is switching although it seems to be switching when the gas analyser shows the lambda is reading high.
    I originally thought that the MAF was dying but the customer wants to sell the car so he bought a secondhand one. Breather hoses are as clean as a whistle.
    Two fault codes in memory, P0170 Fuel trim and P0500 VSS.Both of these codes return when cleared.
    So now I don't know if the replacement MAF is just as bad as the original. I could replace the lambda sensor but as it is switching I thought a "brisk roadtest" might bring it back to life.
    Is the VSS code likely to be genuine or is it just displaying because the car is not moving?
    Some fresh ideas would help a lot.
    Thanks, Shaun

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