17 Grandsport A8
Got Btr stage 3 cam
katech ported heads
gpi 4.070 pistons & rods
Gpi sent a tune out to get the car started but unfortunately the car isn't starting. Just looking to see if anybody has an idea on what the issue is.

posted a short video of the example. Car just does it repeatedly. Help would be greatly appreciated

 

Almost impossible to diagnose with just a video...if you have a scan tool (not code reader) see what codes may have set....see what modules you can and can't communicate with.

 

It starts,,,,, it just doesn't keep running.
Seems like a fuel issue.

 

• Double check all your grounds
• Be sure the small black wire that goes to the negative terminal on the battery is in place
• Check the fuel pump module
• Check both fuel pump fuses. Should be one under the hood and one under the rear cargo area carpet

Check engine light?
Codes?
Other mods (like a flex fuel sensor)? If you added E85, disconnect the sensor and see what happens. There was a post on here awhile ago and the sensor was bad causing the car to shut down.

 

Edit* Uploaded pictures with readable code's & fueling data. With gm scanner. HPFP is acting like it is working.

This is actual vs desired on start up.

All necessary modules are talking and communication.

Chassis control module just has all the exhaust valve codes that can set check engine light.

 

Load your stock tune and see if it runs for more than a few seconds. It'll run like **** and set the CEL but at least then you can eliminate something in the tune.

After the car has been sitting for awhile, do you hear the fuel pump prime when you open the door to the car? Usually has to sit for a hour or more.

Did you check the small black wire going to the battery?

 

I don’t see how you are seeing that all modules are communicating ??…the U0422 is saying the EBCM is not receiving valid data from the BCM and you have 3 communication DTC’s for invalid data on the LIN bus…I don’t see which module in Service Data it is referring to with those 3 U codes…the Immobilizer Control Module is on that LIN Bus…diagnosing communication issues are way over the heads of most repair shops and dealerships…without valid data from the BCM the car isn’t going to start and also with the Immobilizer…I’d look at the BCM and Immobilizer and look at some inputs in those 2 modules to see what might be keeping the engine from starting…if this diagnosis is over your head find a diagnostic shop in your area…they will have advanced equipment like a lab scope to aid in a diagnosis…BTW desired and actual fuel pressure is OK…with engine off ignition ON I’d look at your MAP sensor data PID…you should see about 101 kPa…being that this is an engine rebuild I’d be doing a cam-crank relationship with my lab scope just to make sure engine timing is correct and with your start-stall a pressure transducer in a cylinder to see if spark is occurring BTDC would be helpful…you really need a lab scope to diagnose this…with ignition on if you can go into “live data” in the BCM and Immobilizer that module is communicating.

 

Found info on the 3 LIN Bus DTC’s…looks like the Immobilizer is not involved !!

 

As mentioned before, fuel pump, Maybe it's priming and you get that 1-2 seconds of run but the pump does not stay on to keep it running.

 

That may be a BCM issue.

 

Working on it. Will have an update Monday/Tuesday. Thanks everyone for the responses