I have a 2008 silverado that we took the engine out and put in a 6.0 stroked to 390 with ported prc heads, ls3 intake and injectors, and a 235/239 cam in it. We finished the swap about 2 weeks ago and haven't been able to start the truck.

The truck starts for about 2 seconds and shuts off. We have check all the grounds are connected, we have spark, we have fuel, the ecu is tuned, and the passlock has been removed. We also tried different injectors and throttle bodys and we have the same issue. We tried the ecu on another truck same year and the other truck starts, so we ruled out the ecu. We even changed the crank and position sensors and no good. Wiring seems to be good as the truck was working fine before the engine was taken out.

Anyone that can help me pin point the problem would be appreciated. And I know it is my first post but I been reading threads on here for a long time lol.

Thanks for your time guys!

 

Does it just shut off or stumble and die?

If it just shuts off, Id lean to the VATS;stumble and die, fuel starvation. Do you have a way to log whats going on, HPT or EFILive? What was "tuned" on the ECM?

 

Ask your tuner the status of the VATS (vehicle anti theft system)

It sounds like thats what is shutting it off. Of course this is assuming a strong fire and a sudden shut off.

 

Unfortunately I do not have a way to log what is going on. The truck starts for like half a second then stumbles and dies. I tried changing the injectors to the stock 6.0 injectors and got the same result.

I got the computer tuned by a guy with hptuners. He supposedly adjusted for the ls3 injectors, throttle, and intake. He lives 2 hours away and a friend took the ecu with him to the guy as the engine was rebuilt and needs to break in. He also removes the VATS and passlock.

It starts strong and suddenly shuts off sometimes too, but thats after a few tries.

Also the clock spring broke when removing the airbag. Would that affect anything?

 

Send a note to your tuner and ask him. If the VATS are still active then it could be a likely cause.

 

Yea I did ask. He said it is removed and the truck will start better with starting fluid. Which made me check the fuel pressure. Seems fuel pressure is where its supposed to be.mI'm all out of ideas haha

 

Ask tuner if he did a write entire or write calibration after turning off the VATS. A write entire must be performed to turn off VATS on that model.

 

If VATS was still active, does that mean it wpuldnt work on another truck? Because I tried it on a friends truck and his has VATS Removed and his struck started with my ecm.

 

Better question....is that a AES 390

 

To be honest I dont know. The engine was already stroked out when I got it with a truck we bought at the salvage auction. Just rebuilt it and swapped it in my truck.

Had a tech check it for me with a computer. And it seems everything is working and only codes I get is from the airbag from the clock spring. The other code comes from the cluster u0168-00 "lost communication with security module"

I don't know if thata because VATS is removed.