I have a Hummer H3 Alpha 5.3l 2008. 172000 miles. Over the last year I have replaced MAF sensor,all O2 sensors All injectors
coil packs plugs,wires all pvc hoses …. Recently I have gotten codes P0171 and P0174. See attachments for fuel trim…
checked for vacuum leaks with carb cleaner couldn’t find any. Still need to check fuel pressure. Any help would be appreciated

2500 rpm


Idle

 

Check fuel pressure!

 

reset your fuel trims so that it relearns.

 

How do you reset fuel trims? Ty

 

with a good scan tool like a tech2 or equivalent featured one.

 

Reset trims with Tech2. LTFT went back to 27 after a while ran bad at first

 

then next step is to check your fuel pressure like you stated. or there is an air leak between the MAF and the intake. check the accordion bellows for cracks

 

Check fuel pressure not running 60 psi drops to 56 when pump shuts off. Running at idle 60 psi
some needle movement..checked all air intake lines no cracks or issues.

 

are you sure they sold you the correct parts like the injectors or the MAF? do the injectors CC flow like the originals?