A while back I was pulling a hill and heard a pop and since then truck has lacked a little power and fuel mileage went down to 13. Just replace injector pump and lift pump, lift pump is block mounted FASS unit. When you drive it you can fill the turbo working but on the scan tool the MAP sensor will not move off of 14 ever. Is there a way to hook up a pressure gauge to manually check boost pressure before replacing MAP sensor? Or is there something else that could be the problem.
Thanks,

 

You heard a pop? If it came from the engine compartment and not the exhaust id start checking your boots from your turbo all the way to the intake horn. You may have blown a boot and that's where the pop came from and that could be causing the low boost. Easiest way. To check is to first look for a visable hold or damaged boot, if you can't seem to find anything you can take the boot and tube loose from the turbo and the intake horn and pressurize it to say 30psi and see if it holds pressure, if it is loosing pressure get soapy water and spray over the boots and tubes to try and find bubbles. If nothing there try pressurizing just the cac same way minus the tubes. If you loose pressure there in the intercooler than your cac is cracked. If you cant get parts to pressurize it you could put a mix of soap and water (heavy on soap) on the boots and take it for a quick drivetrying to build high boost and pull over or turn around and look for any spots where there is a dry spot or bubbles, that should help find a boost leak if that's your problem. Hope that helps

 

could be your waste gate. i have the exact same truck and the waste gate control piece snaped and i lost boost even with the chip turned full it wus gutless wired the waste gate shut and it works great now

 

With the wastegate stuck open would it blow black smoke? This truck is not smoking, still scratching my head.

 

Depends on how much fueling you have above stock on smoke level and color. Check for boost leaks or like he said the waste gate which I forgot to include

 

mine didn't when it went out