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    Audi S4 1998 2.7 AGB Low boost and multiple codes. Archived Message

    Posted by Michael Whitworth on September 6, 2007, 9:47 pm

    I have in an Audi S3 Avant with a problem with boost and multiple codes, I don't have all info to hand but seems a strange one so I am hoping for any suggestions that may help.

    The car came to me from a trade customer who had previously read and cleared multiple codes which subsequently returned. The main complaint from the customer is his loss of boost.

    I used Vagcom to extract DTCs which I noted and cleared then road tested again. The codes stored were multiple misfire codes, lambda sensor/fuel trim, exhaust gas temperature bank 2, cam sensor bank 2 And positive boost deviation.

    During roadtest I can feel boost but its not fantastic and sometimes it will just lose all boost, when this happens it flags:

    17965 - Charge Pressure Control: Positive Deviation
    P1557 - 35-00 - -

    it will also flag:

    17861 - Exhaust Gas Temp Sensor 1 (G235): Open or Short to Plus
    P1453 - 35-00 - -

    AND

    Acode for camshaft sensor 2 short to plus, I didnt get a copy/save of this one. Although it is noted on jobsheet at work along with all the original codes.

    No previous history with this one I am afraid, I had a good cam sensor available to me so I substituted that with no effect, I have rewired plug at cam sensor due to dirty/coroded terminals, I have isolated and run fresh wire to ecu, I have tested boost from both turbos, although I have no figures I can feel each turbo blowing substantially. I have swapped plugs on exhaust gas temp sensors and this causes it to flag a code for EGTS B1 so I have either got a faulty sensor or more likely the fault is affecting temp on Bank 2.

    The engine runs quite smooth and sweet with no apparent misfires, just a general lack of effective boost when required.I may have missed quite a lot out but only have half the info to hand as I type so I can add more tomorrow.

    Any clues or suggestions would be apreciated.

    Thanks in advance,

    Mike

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