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So ive been trying to fix this issue w/out hopefully needing to change the intake gaskets. Seems thats the most common issue with both these codes simultaneously. Anyway, Ive checked for vacuum leaks, check the MAF, check both the intake/exh bolts. Most i found was a few exh manifold bolts were somewhat loose. Tightened everything. My friend has a smoke leak detector, but he works alot and is seldom available. What else can/should i check before going the intake gasket route. Im assuming this means the 8 individual rectangular gaskets and not the valley cover gasket when trying to resolve this issue.
This is an LS3 btw, ive taken some pics of the live data from my scan tool, but im not proficient at determining what its telling me.I know its short term/long term, bank1-2 and voltages(V) and short term should be almost constantly changing and long term should be mostly steady, but what are good numbers and what is not. Pics attached, both taken with the eng idling in park, any help appreciated, thanks.
Is this a problem that just popped up or is this a new build?
What does the MAF say at warm idle in grams per second?
Seeing as how both LTFTs are about even, and the STFTs are within a couplr numbers of each other, I would assume a leak after the MAF is the most likely culprit.
Not a rebuild, stock eng w/ about 8km miles. Problem started little more than a week ago. I didnt look at the MAF numbers when i ran the scan tool, but i could take another look. I also never did a scan before checking the above mentioned areas. So ive no idea of how much (if any) changed. Since both codes showed up less than 24 apart i assumed the issue is after the MAF as well.
I cleared the codes and driven the car about 18 miles since checking/tightening bolts. There were two ea for both codes (generic pending, generic stored, generic permanent). Only "generic permanent" remains for P0171/0174, but no MIL anymore. If the loose bolts were the issue, hopefully the last two "codes" should go away after xx amount of miles driven, correct? I will run the scanner again tomorrow and post new pics.
Well, after a short drive today the "permanent" code status went away, but about 45 min later both returned. Ive got a smog due at the end of march, so i really want to put this behind me. Here's some new pics, after the old codes cleared, but before the codes returned.
MAF in lb/min
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P0171, P0174 w/ LD 
