So I purchased a 2014 Chevy Silverado Z71 LTZ with the 5.3 with 141k miles. I've done tune up(Bosch double iridium plugs/ duralast wires), changed oil to royal purple, changed trans fluid with filter, changed transfer case fluid, has a rough country CAI, and have a diablo programmer.



I've noticed it consumes gas a lot average about 13.5MPG. Noticed at high RPMs when accelerating it pings and when I have AFM on and it switches from 4 to 8 cylinders it starts to detonate.



I've noticed the pinging happens with 87 tune or even stock tune. I've done fuel system cleaners and even used 91 octane with the same stock or 87 tune and issue still happens. I've been told it could be injector, fuel pressure regulator, or EGR value?



The truck drives pretty decent with normal driving besides the use of a lot of fuel averaging about 13 MPG. I've been told 16 to 17 should be normal?



Any help would be appreciated!

 

tune would have been my guess...ignition timeing to advanced or low octane fuel...but you addressed it. if you have the stock air intake put it back and reset the fuel trims. if it has flex fuel...reset the OH content

carbon filled combustion chambers...maybe do a compression check...maybe its high? have a look in there when the plugs are out.

 

So I replaced the wires and plugs with the OEM ACDelco, issue still happening.



I took my truck over to a local mechanic I know and give them the issues I am having with my truck. They hooked up my truck to their scanner and saw the low-pressure fuel pump loses PSI at high RPM's. They recommended replacing it to see if they might fix the problem but said it might not also, it could be something small or something else not working correctly.

 

What PSI is your fuel pump running at now? Should be 55-62 PSI in a normal modern fuel injected Chevy motor. 60 PSI is perfect-ideal.