Hey guys, so over the weekend I swapped my 4.8 out for a 6.0, I had the computer tuned and put all new sensors and everything on the 6.0 along with some other upgrades such as cam and tbss intake. I go to start it and all it does it crank, no starting, no sputtering, nothing. I swapped the new crank sensor out for the old one that I know works. I have spark, I have fuel in the rails, but after I crank it for a while there is no fuel on any plugs, that makes me think the injectors aren’t firing at all but I’m completely stumped. Tripled checked every connection and grounds. Anyone have any suggestions?

 

Could be something wrong with the calibration in the computer.

Even if the security system was tripped, it would fire and run for 2 seconds before dying.

What vehicle is this in and what camshaft and stuff did you install?

 

yeah the computer did cross my mind. I don’t thinks it’s the VATS because like you said, it won’t even kick on for a second and then die like the vats system does. I am going to call the tuner tomorrow and go through it with him to double check. It’s in a 2000 Sierra 1500, it’s just a lq9 with stock 243 heads. A tsp 228/232 @.600 lift, and a tbss intake.

 

Did you keep your factory MAP sensor with the intake swap?

What about the MAF?

And I assume a throttle body adapter or new larger cable throttle body?

 

I did keep the factory map sensor, swapped it from the original intake to the new one. MAF sensor has been untouched. It is a knock-off throttle body of the Holley 92mm

 

An LQ9 with 243 heads has alot more compression than a 4.8L. That intake and throttle body flow alot more air than the stock unit ever did.

​​​​​​​If the Tune File Does not have the correct values for all the changes you made, It may not want to start.

Discuss with your tuner and let us know.

 

I talked to the tuner and he said the tune looks fine and is a custom tune set up for what’s in the truck. That size intake and tb should work no prob whatsoever. I even tried the carb cleaner in the throttle body and no luck there

 

I'm in the dark without a data log or tune file.

 

Have you checked for power at the injectors using a test light?

 

If you didn't do a re-learn with PCM, you'll have no power to the injectors. I had the same problem with my last build. Did a re-learn and all was well. Once the motor stars, however; you'll need a live tune to get timing just right.