Autozones computer and my own are pulling codes P0171,P0174,and P0101. Ive looked them up and get it for the most part but I dont know exactly what to change out first. The parts involved arent the cheapest so I dont want to buy and replace until its fixed. Ive so far changed the plug to the MAF sensor as I saw copper missing inside one of the contacts. That didnt fix it though. Wheres the next logical step with the given codes coming back?

 

P0171 - Fuel Trim System Lean Bank 1
P0174 - Fuel Trim System Lean Bank 2
P0101 - Mass Air Flow System Performance

Follow the links. They have diagnosis procedures.

 

With those 3 DTC's, fuel pressure and leakdown should be the first thing you test. Key ON, engine OFF, fuel pump running: Pressure must be 60psi to 66psi. Pressure must remain above 55psi for at least 10 minutes after the pump shuts off. Post your results.

 

96+ Fuel System Diagnosis - Blazer Forum - Chevy Blazer Forums

 

I had a p0171 and p0174 and it was a vacuum leak at the air intake.

 

Thanks for the help guys. I tried to listen for a vacuum leak but couldn't find quickly. With the addtional P0101 I'm thinking it might be something else?

 

P0171 & P0174 alone usually means there's a vacuum leak, and following the flow chart would find the problem. When you throw in P0101 after them, you have one of the few combinations of DTC's that the flow chart leads you on a wild goose chase, usually ending with an inconclussive dead end. Low fuel pressure, and or insufficient volume, are the two most common causes when you have all 3 DTC's, in that order.

 

K.I.S.S... When was the last time the fuel filter was changed....