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  1. #1
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    Default Ignition Cut at 0.5 Bar boost

    So, the car is all back together, fuel pressure is set at 2.5 Bar (confirmed with external gauge as I didn't trust the plumbed in gauge) starts and runs absolutely fine, no misfire at all.

    However when I'm out in the car and it starts making boost, feels totally fine until it hits 0.5 - 0.6 bar boost. At which point it feels like the ignition cuts. Not a misfire, definite ignition cut.

    I can see fuel pressure rising with boost, and at 0.5 Bar boost, fuel pressure is 3 bar.

    Anyone have any ideas? Car feels great apart from this.
    1994 Alfa Romeo 155 Q4: Dozeing in the garage.
    2009 Audi A4 tdi: Everyday drive.
    1994 Alfa Romeo 155 , 1995cc Std Standard Black

  2. #2
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    Ok, so reading the manuals tonight, and looking back over what has been done to the car, new fuel pump, new fuel pressure regulator, moving ingnition modules, and what needed to happen to facilitate that, TPS removed from throttle body, I think this is going to be the first place to look, Going to reset the TPS tomorrow, details are in the ignition section of tha manuals.

    One other thing that was a little odd was the fact that the car struggled to start when warm this evening.
    1994 Alfa Romeo 155 Q4: Dozeing in the garage.
    2009 Audi A4 tdi: Everyday drive.
    1994 Alfa Romeo 155 , 1995cc Std Standard Black

  3. #3
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    Success!!!

    Hooked the laptop up to the car this evening, dug out the old VAG connector and fired up StarTrek. First thing noticed was the fact the the TPS was showing an error of Open Circuit.

    Multimeter out and found the TPS was showing 15mV between pins 2 and 3 instead of the required 120mv to 420mv. Adjusted the TPS to 270mv and took the car out for a test.

    Boosted with no problems at all all the way up to 1.35 Bar, or maybe a little more.

    Just goes to show, even the smallest issue can cause big problems.

    Onto the next job.
    1994 Alfa Romeo 155 Q4: Dozeing in the garage.
    2009 Audi A4 tdi: Everyday drive.
    1994 Alfa Romeo 155 , 1995cc Std Standard Black

  4. #4
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    Default

    I am still not fixed/cleaned my Pierburg Valve which is probably causing my ignition cut when my car reaching 1.1bar. Seeing your 1.35bar boost I might have to do it soon
    1995 Alfa Romeo 155 Q4 , 1995 cc Standard Standard Black

  5. #5
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    Default

    Nice one Steve. Will be tempted to check mine for adjustment now!

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