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Chevy HT383 , more cold start problems, engine dies

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  • Chevy HT383 , more cold start problems, engine dies

    Edelbrock kit #357800
    Chevy HT383 Vortec crate engine, brand new
    Duration-196-206 Lift .450" , 21" Vacuum at idle when engine is warmed up
    340 advertised HP
    ACDelco R44LTS Spark Plugs .040" Gap , Pertronics Flame Thrower #40111 Coil Chevrolet Performance spiral core plug wires
    18* Idle timing, 32* total @ 3000 RPM , advance starts at 1200 RPM
    IAC% is at around 12when warmed up to operating temperature
    43-44 PSI fuel pressure, Edelbrock fuel sump, PWM turned on, 29Lb injectors
    MAP # 5017
    Video https://youtu.be/Boofzq9ER1k
    I finally got this thing to cold start somewhat tolerable. But by the time I back out of my driveway and shift from reverse into drive the engine dies. When I start it cold and shift immediately into gear it doesn't die. After 30 seconds the closed loop light comes on and the computer starts leaning it out, then it dies when shifted. When the engine reaches 165* and goes into closed loop self learning mode it shifts and runs perfect. If I add fuel to the cold start modifier it does not help. What really bothers me about this system is I can not wrap my head around how the cold start section of the map works. What is the point of having modifiers if the closed loop is just going to remove the fuel you added? Please watch the whole video before you start sending comments. Yes I did try adding more idle timing and it did not help. If you notice in the video the spark advance jumps to 41, the IAC goes to 78, the inject goes to 12.4 the instant I shift it into gear. I have searched the forum and still have not been able to find an explanation of how the cold start section of the map works that matches the experience I have had with it. Thanks in advance for help!

  • #2
    have you called the techline?

    I wonder if you should try a leaner map like 5006. You're AFR is super rich when the 02 sensor comes online and your Short Fuel trim maxes out at -30. It's trying to remove fuel but then on top of that then you keep ADDING more fuel with the cold enrichment. Somethings not right.

    Comment


    • #3
      Originally posted by CMerchant View Post
      have you called the techline?

      I wonder if you should try a leaner map like 5006. You're AFR is super rich when the 02 sensor comes online and your Short Fuel trim maxes out at -30. It's trying to remove fuel but then on top of that then you keep ADDING more fuel with the cold enrichment. Somethings not right.
      If you notice, I shift it into gear before the closed loop light comes on and it does not die . In fact it pulls so hard that I have to really clamp down on the brakes to keep the truck from moving . If it is too rich before it goes into closed loop and removes fuel, why does it run perfect when put in gear and not even try to die. It only dies after going into closed loop.

      Comment


      • #4
        How miles have you driven with the PF4 kit installed?
        Don't get too caught up in the numbers.
        Just give the Engine what it wants &
        Let the numbers be what they are.

        Jim McFarland....

        Comment


        • #5
          Originally posted by 2700 Cast View Post
          How miles have you driven with the PF4 kit installed?
          About 1000 miles. Startup has been terrible, but when it is 165* and in closed loop self learn it runs extremely nice, and working with Tommy in the tech department I have been able to get the startup much better , but it still misses a lot on startup and has the problem shown in the video.

          Comment


          • #6
            Watching the video & it dies, is it doing this when in Park ?

            or only when shifting out of Park into rev/drive ?
            Don't get too caught up in the numbers.
            Just give the Engine what it wants &
            Let the numbers be what they are.

            Jim McFarland....

            Comment


            • #7
              Originally posted by 2700 Cast View Post
              Watching the video & it dies, is it doing this when in Park ?

              or only when shifting out of Park into rev/drive ?
              I am shifting from park to reverse in the video when it dies .

              Comment


              • #8
                Cold start fuel adds/subtracts fuel to the Calibration map, only when cold.....it doesn't care what the AF ratio is......it just adds/subtracts fuel.

                Minimum learn RPM is 1200 I believe......its adjustable.

                It's basically pointless for a EFI system to Learn a idle setting.....only altitude changes, and that's covered by a vacuum referenced fuel regulator.

                Yes there are 2 different "Normal" idle's.....ingear, and out of gear.......tune these first.

                The Cold Start Idle is always tuned last.



                Jackrabbiting a cold motor is not a wise thing to do.

                The system will naturally raise the idle speed to warm it up faster.....it can't do this if your moving the gas pedal around, and putting a load on the motor.....you just lost all the cold start fuel settings. So now it's going to rely on what the AFR setpoint is.

                In my neighborhood, if you open your hood to check your oil, and the vehicle still runs after you close it.......Then your labeled the Neighborhood Mechanic.
                https://forums.edelbrock.com/filedat...?photoid=42773

                Comment


                • #9
                  Originally posted by BITE_ME View Post
                  Cold start fuel adds/subtracts fuel to the Calibration map, only when cold.....it doesn't care what the AF ratio is......it just adds/subtracts fuel.

                  Minimum learn RPM is 1200 I believe......its adjustable.

                  It's basically pointless for a EFI system to Learn a idle setting.....only altitude changes, and that's covered by a vacuum referenced fuel regulator.

                  Yes there are 2 different "Normal" idle's.....ingear, and out of gear.......tune these first.

                  The Cold Start Idle is always tuned last.



                  Jackrabbiting a cold motor is not a wise thing to do.

                  The system will naturally raise the idle speed to warm it up faster.....it can't do this if your moving the gas pedal around, and putting a load on the motor.....you just lost all the cold start fuel settings. So now it's going to rely on what the AFR setpoint is.
                  And how do I tune these 2 idles in cold start?

                  Comment


                  • #10
                    Originally posted by wims58ej View Post

                    And how do I tune these 2 idles in cold start?
                    IN GEAR:
                    The motor is cold, and has a load on it ( automatic in gear= foot on brake pedal. Manual in gear= Dyno { poor man's dyno is blocked front wheels on pavement, rear wheels on constantly water sprayed surface }.
                    In the App:
                    Home Screen.
                    Advanced Tuning.
                    On/Off Options.
                    Make "Idle Control" turn RED..........if motor runs better when it's GREEN. Then change it back.

                    If the above doesn't work better.

                    Let the motor cool down for 1/2 hour.

                    Change the Idle Air Fuel Ratio to be richer ( this will help replace the extra needed fuel the O2 sensor takes out, when it comes on line ) in 0.20 steps, till you have a usable, smoothest idle.

                    ​​​​​​

                    OUT OF GEAR:
                    Do the above first ( In Gear ).
                    If idle is not smooth. Then adjust timing.....you will most likely need to drop it down 2 numbers.


                    You can try the above to see what works best.
                    In my neighborhood, if you open your hood to check your oil, and the vehicle still runs after you close it.......Then your labeled the Neighborhood Mechanic.
                    https://forums.edelbrock.com/filedat...?photoid=42773

                    Comment

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