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Thread: 05 GTO A4, cammed cold start troubles...

  1. #1
    Tuner in Training
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    05 GTO A4, cammed cold start troubles...

    I have a 2005 GTO Auto with a 3200 Vigilante converter, Pacesetter longtube headers, magnaflow catback, Lingenfelter cold air intake, ported throttle body and a 228/232 .588/.595 114LSA cam... When we first installed it, on stock tune it would fire right up and idle on cold start, warm start it did not like at all and would die instantly.

    Working with a friend that does a lot of tuning, we got the car warm starting and idling good last night, but as I feared, cold start this morning stumbled and died quick... my neighbors were not happy with me revving the car to get it running at 6:30am...

    Attached is the current work in progress file as well as a log from last night with it idling at 800RPM, I played with the Minus spark option in the VCM Scanner a bit in that log too.

    Also there is a log of my first attempt at starting the car this morning, and the next start where I held the rpms over 1000 and pulled the trans back into R. When I let off in R it surged back twice (You can see this in the log) and I almost hit my neighbors car.

    Any suggestions on where to go from here? I have been thinking making the Startup airflow in colder temps needs bumped up more?
    2014 Corvette Z51 M7
    A&A Vortech V3 SI on 3.8" Pulley, Texas Speed 1 7/8" Catless Longtubes, MightyMouse Gen 5 catch can, LT4 High Pressure Fuel Pump
    617rwhp/575rwtq

  2. #2
    Senior Tuner
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    A few things:

    1: Idle Base spark is too high. Put it back to stock for now on both the Base, High and Low tables.
    2: Set your High RPM Disable to 100 and your High RPM Re-enable to 0. You have it at 400/300 right now.
    3: Get your fueling right at idle via the MAF. You haven't touched anything on the MAF curve for idle.
    4: Once the above is done, and fueling is correct at idle, then you can dial in the Idle Airflow tables.
    Formerly known as RWTD

    Toys: '22 Tesla Model S Plaid / '20 Chevy Duramax / ?20 Sea-Doo RXT-X (2)

  3. #3
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    Quote Originally Posted by RWTD View Post
    A few things:

    1: Idle Base spark is too high. Put it back to stock for now on both the Base, High and Low tables.
    2: Set your High RPM Disable to 100 and your High RPM Re-enable to 0. You have it at 400/300 right now.
    3: Get your fueling right at idle via the MAF. You haven't touched anything on the MAF curve for idle.
    4: Once the above is done, and fueling is correct at idle, then you can dial in the Idle Airflow tables.
    But the fuel trims look pretty close? I am lost on getting this thing to startup and idle correctly and have read more threads on these forums in the past 2 days then I have in my life and doing so just confused me more

    I will set base spark back to stock (13*)... If the fuel trims look pretty decent how much is there to gain in messing with the MAF curve at idle?
    Last edited by SK360; 06-10-2009 at 01:02 PM.
    2014 Corvette Z51 M7
    A&A Vortech V3 SI on 3.8" Pulley, Texas Speed 1 7/8" Catless Longtubes, MightyMouse Gen 5 catch can, LT4 High Pressure Fuel Pump
    617rwhp/575rwtq

  4. #4
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    I made the changes you suggested

    And I followed 5 Liter Eater's Idle guide and while it did idle well I think the RAF numbers the histograms spit out were way too high, the car lunged forward in 1st with a slight throttle input, and letting off in 3rd the car would hunt.... Don't think that guide is too A4 friendly as doing the scans in gear with the E Brake on does not make much sense to me

    Fuel trims are within +/-2 at idle

    Ended up bumping the first few seconds on Startup Airflow by +7 to get the car to start in my driveway this morning

    Will post tune/logs soon
    Last edited by SK360; 06-11-2009 at 08:06 AM.
    2014 Corvette Z51 M7
    A&A Vortech V3 SI on 3.8" Pulley, Texas Speed 1 7/8" Catless Longtubes, MightyMouse Gen 5 catch can, LT4 High Pressure Fuel Pump
    617rwhp/575rwtq

  5. #5
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    Ok here is a log and tune file revised from yesterday... it sounded really nasty on start, couple of sounds that sounded like rod knock then it flared and settled down to idle... it idles really rough and I notice MAP is higher then with the increased idle spark table I had before...

    suggestions?
    2014 Corvette Z51 M7
    A&A Vortech V3 SI on 3.8" Pulley, Texas Speed 1 7/8" Catless Longtubes, MightyMouse Gen 5 catch can, LT4 High Pressure Fuel Pump
    617rwhp/575rwtq

  6. #6
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    I got the knock sound on startup a few times today... is this normal?
    2014 Corvette Z51 M7
    A&A Vortech V3 SI on 3.8" Pulley, Texas Speed 1 7/8" Catless Longtubes, MightyMouse Gen 5 catch can, LT4 High Pressure Fuel Pump
    617rwhp/575rwtq

  7. #7
    Quote Originally Posted by SK360 View Post
    I got the knock sound on startup a few times today... is this normal?
    Sounds like you have too much startup airflow.

    Are you running a wideband? If so, can you upload your config? Your VE and MAF tables are stock, so I'd start by tuning those. Your AFR can't be on everywhere with that big a cam and t/b with those tables stock.

    Just my $0.02.

    Gerry
    06 M6 GTO - L92 Heads - Flowtech AK-47 cam - ported LS3 intake - ported TB - Kooks 1 7/8 - Cats - SVEDE OTR CAI - H-Pipe - Flowmaster Super 40s

  8. #8
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    Quote Originally Posted by ShoddyHog View Post
    Sounds like you have too much startup airflow.

    Gerry
    good to know!
    love forum and all precious info!!!