Throwing lean codes need help!!!

[JerseyTrueBlue]

Im throwing codes p1000 system test incomplete, and p0171 and p0172 system too lean. My car is idleing horrible, missfiring and almost stalling I need help finding out how to fix this it's dangerously lean. My vacuum lines are all good as well as exhaust leaks and any other hoses. Car is a 2001 GT with a new crate motor swap (same 2v motor just brand new) I'm running my old ecu and just lately a predator tune to try and fix the problem which did nothing for me. Motor is not modified besides full exhaust it keeps getting worse and I can't afford to ruin my new motor if anyone has any tips it's greatly appreciated I'm running out of solutions

 

[Crimson2v]

Check for any intake leaks also, or possible MAF. You are getting unmetered air into the engine and that is where the codes are coming from.

 

[squeak93]

90% of the time the lean codes are unmetered air. Check and triple check things. May try a new maf as they can cause the issue (had an aftermarket C&L trip these exact codes on mine, new/used stock maf fixed it perfect). Check all connections again and then again. Did u buy the crate engine from intake down? If so its possible the lower intake gaskets didn't seal. Good luck and take your time. Don't drive it till you find the leak.

 

[fast97gt]

check the silicone ducting tubes at the maf, if all is well then its possibly the maf. look also at the pcv lines and other LARGE lines. cracked intake, i wouldnt think so but also possible. i see you have a tb and upper plenum, check the gaskets there

 

[joshjwc9]

If you cannot find any leaks in the intake side, try adding some fuel to your Diablo tune...

 

[lang williams]

i chased that problem recently an it was the maf. spraying around the intake didn't reveal a leak