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    Porsche Boxster 2.5l high lambda Archived Message

    Posted by Shaun Dale on July 14, 2008, 12:19 pm

    This car seems to have done the rounds!
    Gas results after a fast idle to light up the catalyst:-
    O2 0.92%
    CO2 13.2%
    HC 136ppm
    CO 0.06%
    Lambda 1.044
    The problem is fairly old as the lambda on the 2006 MOT was 1.006 but in 2007 it was 1.023, although the car does a fairly low annual mileage.
    It has a very slight misfire and sounds just tiny bit lame at tickover/fast idle.
    Previously a "Porsche Specialist" has tried a new MAF which didn't help so they refitted the old one. Another garage fitted new lambda sensors and stripped the threads in the cats so they are all new. Still it has the problem.
    There are no codes in memory (not in EOBD anyway).
    I have checked for manifold airleaks, blocked off the breather pipe, servo vacuum hose and evap canister hose.
    STFT is about 0% (it goes pos and neg by about 4%). LTFT is about -4 to -5% on both banks.
    Both pre-cat lambda sensors are switching but possibly rather slowly.
    I was worried that there might be faulty injector (delivering short measure) but surely that would cause an imbalance between the banks and also cause the other cylinders to richen up.
    Or am I still looking at a tired old MAF (it is Bosch after all).
    I think I may have to check the plugs for colour and do compression tests, but the layout of this engine makes all that a right pain!
    Any ideas, what am I not seeing?
    Shaun.

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