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Thread: Hot start issues (low mount turbo heat soak)

  1. #1

    Hot start issues (low mount turbo heat soak)

    Hey Guys

    Im having some issues with a 2011 Holden VE SS that has had a low mount twin turbo kit fitted. blower cam, ZL1 pump, xspurt 725cc injectors.

    If you let the car sit for a minute, Manifold air temp rises to between 60 - 90 degrees Celsius. When you attempt to start the vehicle it coughs and splutters
    for a few moments, then dies. My wideband shows AFR in the 20s. Injector pulse width fluctuates up and down, but stays around 1.0 - 2.5.
    If you give it throttle it still dies, spark fluctuates but should have enough for idling 12 - 20 degrees.
    It definitely feels like a lean issue, once running my VE is pretty much spot on at idle (maybe slighty rich). Im running a 2 bar operating system.

    I do have some doubts with these injectors, as they have no plug and play data, I usually use Deatchwerks. I have had hot start issues in the past
    with uncommon injector brands, but these had a leaking issue.

    I have played around with cylinder charge temp bias with no luck, The only way to improve the issue is to add to the charge temp multiplier.
    With a 1.3 multiple it takes my Commanded AFR down to around 12.0. The car starts fine but with the multiplier set at a specific charge temp
    it stays active and richens up my Idle AFR all of the time.

    This does not run an IAT2 sensor so Manifold air temp is calculated.

    Is there a way to have After start enrichment without it affecting fueling under normal operation?

    Thanks in advance.

  2. #2
    Senior Tuner kingtal0n's Avatar
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    Sorry but i Don't have a gen4 to compare with, so I am curious: How does the IAT rise when its shut off, if there is no IAT sensor? is that what you are saying?

    Surely the coolant temp isnt rising causing calculated manifold air temp to rise?

    In either car. I had an issue like this with iat rising from heat soak.
    My first response was to install an adjustable resistor so I can turn it right or left and increase ~1000 ohms to drop the air temp as necessary while driving

    Next I decided to relocate the IAT to a more favorable location. To eliminate the dial.

    Finally I learned in the computer to disable the charge bias (after playing with it for some number of days) because it was playing my IAT adjustments against coolant temp adjustments and screwing over the entire VE map everytime the coolant temp went up or down some, in the areas I specifically asked coolant temp to 'help' with correcting false IAT. In other words, It sounds like a great plan to use coolant temp to help 'stabilize' the iat. However there were so many situations where this screwed the fuel tables up, I stopped using it.
    Last edited by kingtal0n; 07-16-2019 at 01:23 PM.