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Thread: LS engine hard start and dies when pressing accelerator hard.

  1. #1

    Default LS engine hard start and dies when pressing accelerator hard.

    Having a little issue here. I put a LS engine in my 1971 Camaro and installed a Holley Terminator LS 550-609 Kit. I programmed it with a LS1/4L60E base and imputed my specific parameters and did a self Learning. Car idles fine when warm and sounds great. But on initial startup, I have to "give" it gas like an old carbureted engine, and baby it until it starts. After that I have to hold the gas in to keep it from dying. Once the temps goes up it will idle on it's own. But after that if I mash on the gas, the car will bog and spurt a little until I let off the gas. But if I ease into it, it's fine.

    Any ideas? I made sure to use all new Delco sensors and what ever the manual suggested to use. Basically all of the gaskets and sensors are new and I tried to pay attention to torque specs to insure no vacuum leaks. Brake booster and hoses are new as well. Fuel system is new and I installed a pressure sensor on the fuel rail. Looking at the screen when running the car it holds constant pressure. Around 57-58 psi. I'm using the firmware that came preinstalled on this system, hadn't updated that yet. Could it be the IAC valve? I'm running DBC and and contemplating converting this system over to DBW to keep it simple and not have to deal with those two sensors on the throttle body.

    Here's a list of what I have on my engine. Maybe someone can see something I don't. I just copied it from a spreadsheet I keep on hand.
    Part # or Name:
    Engine 2004 Silverado 5.3L Long Block (Stock)
    Transmission 2004 4L60E (Corvette servo) Stock Torque Convertor
    Coils Stock LS1 Camaro
    Spark Plugs NGK TR55
    Plug Wires MSD
    Injectors Stock LS1 28 # 0280158931
    Fuel Rail Stock LS6
    Fuel Pump Spectre Fuel Tank and Pump 2nd design
    Fuel Return Corvette Fuel filter regulator
    Intake LS6 Intake with LS6 PCV System
    Intake Gasket Fel-Pro 92438
    MAP sensor Delco 16212460
    Throttle Body LS1 w/Brown spring (Brand new)
    Throttle Body Gasket Fel-Pro 61069
    IAC Valve BWD 31033
    Exhaust Manifolds Hooker #850 1HKR
    Exhaust Manifold Gaskets ACDelco 12617944
    Exhaust 2.5" Pypes SGF11 with Street Pro Mufflers
    Lower Radiator Hose
    Upper Radiator Hose Gates 22352
    Water Pump ACDelco 252-846 Tapped for Steam Vent
    Valve Covers Stock 2004 GTO
    Valve Cover Gaskets Fel-Pro VS50504R
    CTS Sensor ACDelco 213-4514
    Knock Sensor ACDelco 213-3521 (2)
    Knock Sensor Harness Dorman 917-033
    Oil Pressure Sensor ACDelco D1846A
    Air Cleaner Temp Sensor ACDelco 213-243
    A/C Bracket Holley 20-134
    PS Alt Bracket Holley 20-135
    Belt Tensioner Dayco 89337
    Belt Gates K060990
    Brake Booster Vacuum Hose ACDelco 176-1708
    Alternator Large Case 145 Amp GM 15754097
    PS Pump GM 26120639 (Aluminum)
    PS Pulley Dirty Dingo 5" Pulley for LS Camaro
    PS Reservoir GM 26046502
    PS Reservoir Bracket GM 125552222
    PS Reservoir Cap GM 10317982
    PS Reservoir Hose GM 15907878
    Engine/Transmission Control Holley Terminator LS MPFI 550-609

  2. #2
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
    22,940

    Default

    Seems like the EFI system needs to be tuned. which base calibration did you use to create your base calibration? Is the ECU actually Learning (Learn Table values being populated)?
    http://forums.holley.com/showthread....ents-Read-This! (Initial Checks & Adjustments - Read This!)
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 11.8:1 comp, TFS R-Series intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 160A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, M4602G aluminum driveshaft, FRPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 tires.

  3. #3

    Default

    I'm pretty sure I'm still on Version 2 (I'll need to double check), but in the custom calibrations Global Folder I started with the file named LS1 4L60E - Cable Throttle Body.
    I left everything pretty much the same except for Engine Displacement under System Parameters. I changed that to 323 CID. Thanks for the info, I'll check that out and start going through the checks.

    Here's my Global Folder if anyone cares to look at it, maybe someone can see something I don't.
    Looked at my fuel Learn Table and it looks like a mess, lots of zeros, don't know if that's normal.

  4. #4
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
    22,940

    Default

    Quote Originally Posted by 1971camaroguy View Post
    But on initial startup, I have to "give" it gas like an old carbureted engine, and baby it until it starts. After that I have to hold the gas in to keep it from dying.
    Ensure the idle speed screw on throttle body, has been adjusted to achieve an IAC Position of about 5% at hot idle.
    Remember to perform another TPS AutoSet, whenever you adjust the idle speed screw on the throttle body.
    In the Idle ICF, the "Target Idle Speed (RPM)" must be programmed to the desired RPM speed at hot idle.
    Ensure the proper type of Advanced Idle Control is selected in Idle Settings. "Slow" may provide the best idle quality.
    FYI: Some throttle bodies require a 10% IAC Position at hot idle, due to increased airflow caused by further thermal expansion.
    http://forums.holley.com/showthread....neral-IAC-Info (General IAC Information - Read "IAC NOTES")

    Once the temps goes up it will idle on it's own. But after that if I mash on the gas, the car will bog and spurt a little until I let off the gas. But if I ease into it, it's fine.
    You may need to increase the Acceleration Enrichment parameters (especially the AE vs TPS Rate of Change).
    Acceleration Enrichment can't be tuned until the Base Fuel Table is well tuned.
    If you have a momentary lean spike, on light throttle acceleration, check
    your AE vs TPS/MAP RoC Blanking values (in Fuel Modifiers/Fuel Control):
    If they're 15 & 7, those are the old values from the V1 ECU firmware.
    Change the AE vs TPS RoC Blanking value to 4-6.
    Change the AE vs MAP RoC Blanking value to 5-7.
    Some users reported the need for an even lower TPS RoC Blanking value.
    Ensure there's no TPS/MAP RoC signal activity at idle, due to noise/kPa fluctuation.
    http://forums.holley.com/showthread....1379#post61379 (AE Tuning Information)

    I'm pretty sure I'm still on Version 2 (I'll need to double check), but in the custom calibrations Global Folder I started with the file named LS1 4L60E - Cable Throttle Body.
    Yes, you're on V2 EFI software/ECU firmware. Yes, that's the right base calibration.
    http://documents.holley.com/techlibr...0_overview.pdf (Holley EFI V4 Software Overview)

    Looked at my fuel Learn Table and it looks like a mess, lots of zeros, don't know if that's normal.
    There's nothing wrong with your Learn Table. Not every cell of the Learn Table will be populated, only the areas you operated in.

    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 11.8:1 comp, TFS R-Series intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 160A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, M4602G aluminum driveshaft, FRPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 tires.

  5. #5

    Default

    Thanks, I'll check what you suggested. You've been helpful.

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