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Discussion Starter · #1 ·
As of late I have been battling an on and off again P0171. I ended up taking it to a shop and they have been running tests for days now and finally just did a smoke test and are claiming my catch can is leaking air as well as my XAIR intake. I recently installed the XAIR, however prior to that I had a Vararam on my car for the last 10+ years. I find it interesting it's only throwing the code on bank 1 and not bank 2 if it's unmetered air getting in. Does their diagnosis make sense? I plan to replace all the hoses on my catch can and rework the couplers on my XAIR intake regardless.
 

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do you have a way to log fuel trims?

one bank is usually slightly different than the other. One may have trims just high enough to trip the code.
 

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Discussion Starter · #3 ·
I have an ultra gauge so I can monitor them real time, but no way to log. They eyeball test does show bank 1 adding more fuel on average.

do you have a way to log fuel trims?

one bank is usually slightly different than the other. One may have trims just high enough to trip the code.
 

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Are the mods in your signature up to date (besides the Vararam)? Stock tune? The XAIR could have just leaned the car out enough to trip a bank 1 lean code. Able to put the Vararam back on and see if the trims come back down?
 

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Discussion Starter · #5 ·
Yeah, other than the XAIR everything else is up to date. The code actually first tripped a year ago when I had the Vararam on, but eventually cleared on its own. It just came back again after having the XAIR on for a few hundred miles.

Are the mods in your signature up to date (besides the Vararam)? Stock tune? The XAIR could have just leaned the car out enough to trip a bank 1 lean code. Able to put the Vararam back on and see if the trims come back down?
 

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The Entenmann's Shim-Sham
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I would also shoot some carb cleaner around the fuel injector ports and intake ports for Bank 1, just to make sure that an o-ring hasn't failed.
 

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A stock motor with a stock tune shouldn't set a lean code with just the addition of a CAI, so you very well could have a small leak somewhere that just enough to trigger one of the banks to go lean.

Are you able to see what percentage the trims are at on each bank? A lean code gets triggered whenever either bank is adding more than about 15% fuel.
 

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Discussion Starter · #8 ·
The shop did a smoke test and said there were no leaks around the intake manifold.

I would also shoot some carb cleaner around the fuel injector ports and intake ports for Bank 1, just to make sure that an o-ring hasn't failed.
 

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Discussion Starter · #9 ·
Yes, I do see it occasionally jumps above 15% on bank 1.

A stock motor with a stock tune shouldn't set a lean code with just the addition of a CAI, so you very well could have a small leak somewhere that just enough to trigger one of the banks to go lean.

Are you able to see what percentage the trims are at on each bank? A lean code gets triggered whenever either bank is adding more than about 15% fuel.
 

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What does bank 2 look like? Ideally you want your trims to average between +/- 5%.
 

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The Entenmann's Shim-Sham
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The shop did a smoke test and said there were no leaks around the intake manifold.
Smoke tests don't always reveal a leak. I've seen instances before where a leak source wasn't discovered until the engine was running and an indicator was sprayed in the direction of the airflow.
 

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Was dealing with the same issue. I replaced my evap purge solenoid and o2 sensors code never came back up.

As of late I have been battling an on and off again P0171. I ended up taking it to a shop and they have been running tests for days now and finally just did a smoke test and are claiming my catch can is leaking air as well as my XAIR intake. I recently installed the XAIR, however prior to that I had a Vararam on my car for the last 10+ years. I find it interesting it's only throwing the code on bank 1 and not bank 2 if it's unmetered air getting in. Does their diagnosis make sense? I plan to replace all the hoses on my catch can and rework the couplers on my XAIR intake regardless.
 

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Freedom Fighter
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@skipopeye helped me troubleshoot this issue a couple years back. My driver side fuel trims were jacked and the car was running like dogshit. Turned out after a shorty header and midpipe install, the primary o2 sensor wire was leaning against something hot and burned through. I replaced my o2 sensor and it'd been good ever since. You might have a front o2 sensor on the fritz.
 

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Discussion Starter · #14 ·
I reinstalled my XAIR and installed a new oil catch can from Elite Engineering, also put hose clamps on all the catch can connections. Today my P0171 came back on with his friend P0174. All my connections looks secure and I don't see any obvious places where a leak could be. I plan to try cleaning my MAF next, however at idle is ~ 7 g/s which seems to be within spec.

My o2 sensors are fine, no issues with those.
 

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GR-RRR!
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I think it is time to pull the intake manifold off and look for cracks or for misaligned or damaged gaskets. Be sure to check that the fuel injectors are well seated and have undamaged o-rings and that the MAP is properly seated and that the vacuum lines at the back are not leaking. If this is an LS1, make sure the TPS and IAC are working and not leaking.
 

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FWIW, the most likely possibilities are that the MAF is either reading incorrectly (dirty or bad), or reading correctly and there is unmetered air getting in.

you can get wonky readings if you either plug the MAF connector in backwards (hard but possible) or have the MAF itself installed backwards, but IIRC it results in the opposite effect of what you are dealing with, i.e. "system too rich."
 

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is the maf screen still intact? was your car tuned for the vararam, or did you have it retuned after adding the xair?
 
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