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Thread: is this normal overload protection?

  1. #1
    Mitsu booster
    Join Date
    Apr 2011
    Location
    Stockholm
    Posts
    6

    is this normal overload protection?

    This is my first turbo car so please bear with me...

    Background; 2.2 1989 GTC Lebaron, M/T, Garrett stock turbo, new cylinder head, recently remanufactured turbo, the only issues I am aware of are minor oil leak around the PCV valve + TPS fault code 24 (TPS is new and also SMEC/ECU, but thats a separate mystery I guess). Low oil consumption. Fuel consumption normal. I have changed ignition timing to just slightly earlier than when car was checked at shop - this is because it didnt run good (shop didnt have exact equipment so I am not sure they were right anyway).

    Anyway, this question is about the turbo overload. Acceleration is smooth and nice from vac to boost, specially with the boost gauge at 2-10, but when increasing boost the overload protection kicks in at 12-15. Which in it self is normal (and afterwards, I get a new fault code for turbo boost excess=OK).

    What I am wondering is about the way the protection kicks in - brutal. The whole car shakes, as if I had instantly stepped/released brake pedal. (It was there before turbo reman too, and also with other ignition timing).

    Is this normal? If not, theories on why? Something I can do to get a smoother protector?

    Thanks from Sweden

  2. #2
    turbo addict
    Join Date
    Dec 2005
    Location
    Pickering, ontario
    Posts
    2,670

    Re: is this normal overload protection?

    Exceeding 14 psi on a stock controller will get the harsh shut off of overboost protection.
    It's possible to remove the overboost protection through a custum made computer chip and associated fuel upgrades.
    It's also possible to defeat the overboost protection on the factory computer, both electrically or pnumatically.
    There is no changing the harshness of the overboost protection.

    I would look into the reason for the overboost condition. Your boost should be around 11 psi. The reasons for the overboost are incorrect vacuum lines to wastegate actuator, seized wastegate lever, incorrect or faulty actuator, or faulty boost solenoid.

    I would suggest you look into the actuator adjustment using regulated compressed air or possibly using a manual boost controller.

  3. #3
    turbo addict
    Join Date
    Dec 2005
    Location
    Spokane, Wa
    Posts
    9,046

    Re: is this normal overload protection?

    Sounds like you have a vac leak somewhere.

  4. #4
    turbo addict
    Join Date
    Jan 2007
    Location
    South Gillies, ON. Canada
    Posts
    2,923

    Re: is this normal overload protection?

    time to study your vacuum diagrams, start at the turbos waste gate actuator and work your way back.
    1988 Lancer Shelby 2.2TII 1989 Shadow ES 2.5TI 1992 Lebaron Sedan 3.0Auto 1993 Acclaim 2.5TI-A520 Hoard parts now!

  5. #5
    Mitsu booster
    Join Date
    Apr 2011
    Location
    Stockholm
    Posts
    6

    Re: is this normal overload protection?

    Thanks a lot guys, and yes it was a vacuum issue.

    One new OEM PCV + new 3-way rubber connector next to it + fixing a bad tape repair on thin vacuum line to turbo gauge = no overboost plus runs helluvalot better, at a more than reasonable cost.

    I guess I will do some googling on the PCV function to understand what I just did... Thanks again.

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