6.4 No Start issue

[WJW]

Hi All
Looking for thoughts and suggestions
I have a 2020 6.4 w/ 8hp70, Sublime quick start set up with stock engine harness. I connect the battery power to engine harness, grounds are all connected, I connect ignition to power, then connect key on which cycles the throttle body and fuel pump primes system, all good to this point
Then I go to hit start button, engine cranks, fires and runs for about 4 seconds and dies. I thought it might be gas pedal calibration but pedal seems to work in the 4 seconds or so that the engine starts.
Then thought maybe it TPS, so I bought a OBD2 code reader, no luck there as it is asking for a vin number. I bought the engine from a salvage yard a year ago, yes I saw it run, but never got a vin
Any thoughts on what might be causing this?

 

[PLUM_72]

Hi All
Looking for thoughts and suggestions
I have a 2020 6.4 w/ 8hp70, Sublime quick start set up with stock engine harness. I connect the battery power to engine harness, grounds are all connected, I connect ignition to power, then connect key on which cycles the throttle body and fuel pump primes system, all good to this point
Then I go to hit start button, engine cranks, fires and runs for about 4 seconds and dies. I thought it might be gas pedal calibration but pedal seems to work in the 4 seconds or so that the engine starts.
Then thought maybe it TPS, so I bought a OBD2 code reader, no luck there as it is asking for a vin number. I bought the engine from a salvage yard a year ago, yes I saw it run, but never got a vin
Any thoughts on what might be causing this?

What harness did you use? The old ballast resistor wires, the Blue and Brown, should be connected to the pink wire on the Mopar/Direct Connection Harness. Other harnesses have similar connections. If you're running a Sound German trans controller, their yellow wire gets hooked up here too. The blue and brown give both cranking and run voltage.

 

[WJW]

What harness did you use? The old ballast resistor wires, the Blue and Brown, should be connected to the pink wire on the Mopar/Direct Connection Harness. Other harnesses have similar connections. If you're running a Sound German trans controller, their yellow wire gets hooked up here too. The blue and brown give both cranking and run voltage.

Hi Plum_72
I am using sublime technology quick start system with stock engine harness, I do have the Sound German connected to ground and power when trying to test start. Cranks and fires up but dies right away.

 

[heminut]

I recommend you post this over on the forabodiesonly forum in the late model hemi swap section too. There are a lot of guys over there dealing with the aftermarket systems being used in this type of swap and they seem pretty knowledgeable about this stuff.

 

[Challenger RTA]

In general.
If you are referring to a vehicle ignition system that starts and runs for a few seconds then dies, this is a known diagnostic scenario often linked to fuel, spark, or security system failures:

• Fuel System: A failing fuel pump check valve, clogged fuel filter, or bad fuel pump relay can cause the engine to run briefly on residual pressure then stall.
• Ignition/Security: In fuel-injected bikes (like Harley-Davidson), a P1010 or P1009 error code indicates a missing/VIN (VIN on the motor?) or incorrect password, often caused by a turn signal module not receiving a complete message from the ECM. Disconnecting the battery or ECU can reset this.
• Sensors: A faulty Intake Air Temperature (IAT) sensor or crankshaft position sensor can cause immediate stalling after startup.
• Immobilizer: In cars, an anti-theft immobilizer may cut fuel or spark if it fails to recognize the key, often flashing a security light.
• A bad or disconnected Mass Air Flow sensor will start and run but will have no power.

Here again back to basics. Check if you have fuel and spark.
I have to say. I'm not an expert on this but experienced my share.
As @heminut said. You may be contact someone there.

and they seem pretty knowledgeable about this stuff.