2011 5.3 having lean codes P0171 P0174. and the truck doesn't run like it used to it drinks gas bad. we put new gm intake gaskets, new maf sensor, checked ohms on injector, checked injector orings, replaced the driver side valve cover, and prayed carb cleaner around intake no change in rpm, I've attached a data log any info I would appreciate it.
correct data log
Just a couple of thoughts since don't have a tune or anything to go by. It looks lean, substantially so at points and then goes back to normal like fueling. Are any codes at all set? Does it sputter at idle particularly at any time at all? Idle weird at times? Engine make any noise or getting gas at a different "cheaper" station recently?
Check to make sure your MAF is clean. Check to make sure your plugs are good. Check to make sure your purge valve isn't leaking. Might also want to check fuel pressure with a gauge while driving and hitting wot...
2010 Vette Stock Bottom LS3 - LS2 APS Twin Turbo Kit, Trick Flow Heads and Custom Cam - 12psi - 714rwhp and 820rwtq / 100hp Nitrous Shot starting at 3000 rpms - 948rwhp and 1044rwtq still on 93
2011 Vette Cam Only Internal Mod in stock LS3 -- YSI @ 18psi - 811rwhp on 93 / 926rwhp on E60 & 1008rwhp with a 50 shot of nitrous all through a 6L80
~Greg Huggins~
Remote Tuning Available at gh[email protected]
Mobile Tuning Available for North Georgia and WNC
Smoke test for leaks.
2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.
If you don't post your tune and logs when you have questions you aren't helping yourself.
the only codes i can get it to set are p0171 and p0174 and the rarely seen p0300 and it does have a random rough idle in park after it gets to operating temp. engine sounds good and acts healthy still pulls good and starts fine. as far as gas goes I fill at one place and use 93 since the build. I really do appreciate all the help sir.
is there any areas i should look for in particular when doing the smoke test ? or places i can check before i go get one done ?
Intake gasket area, injector o-rings, brake booster fitting, map sensor seal, exhaust manifold gaskets and y-pipe connections.
Those are the most common spots.
2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.
If you don't post your tune and logs when you have questions you aren't helping yourself.
From the looks and sound of it, especially with it "drinking" gas it's most likely a vacuum leak. Throw in the random misfire code setting at idle and the fact that I am "assuming" your checking and clearing codes as they're setting, I would say you either have a brake booster issue as previously stated or a stuck open purge valve. The purge valve will "usually" set unwanted flow codes, but that's if you haven't already deleted some of the evap codes or don't have other evap issues like a vent valve that's not sealing (fuel tank has to see a vacuum being pulled on it to set the unwanted flow codes).
Other things that will cause this - air leaks on the engine itself - ie oil cap, broken or missing dipstick, cracked rubber breather plugs around the intake or valve covers or seals or gaskets on the engine in general.
Smoke test will show all of these although you can test while watching fuel trims and then unplugging and plugging off hoses by hand - basically any line attaching to the intake. I would go straight to the purge and brake booster first, then start really digging deep for the other hoses and connections.
2010 Vette Stock Bottom LS3 - LS2 APS Twin Turbo Kit, Trick Flow Heads and Custom Cam - 12psi - 714rwhp and 820rwtq / 100hp Nitrous Shot starting at 3000 rpms - 948rwhp and 1044rwtq still on 93
2011 Vette Cam Only Internal Mod in stock LS3 -- YSI @ 18psi - 811rwhp on 93 / 926rwhp on E60 & 1008rwhp with a 50 shot of nitrous all through a 6L80
~Greg Huggins~
Remote Tuning Available at gh[email protected]
Mobile Tuning Available for North Georgia and WNC
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