P0171 and Snorkel

Fellow taco scuba divers, have any of you had an issue of throwing a P0171 (too lean) code with a snorkel? I don't know if it's a coincidence or not but it seems ever since I put the snorkel on it's throwing a lean code whenever I do longer highway drives. I haven't been able to locate any air leaks, cleaned my MAF, and air/fuel sensor reads ~3.5V on the highway at cruise. Should the MAF not have the ability to compensate for the extra air (in theory) being rammed in through the snorkel? I'm also consistently throwing P0136 "O2 Sensor Circuit Bank 1 Sensor 2", but I don't believe this has any influence on engine performance.

 

I should also add that on one occasion I threw a P2A00 "O2 Sensor Circuit Range/Performance Bank 1 Sensor 1" code but have not done so for a while.

 

Had the same code after my snorkel install. I rushed to button it up as the evening approached. Forgot to tighten the hoseclamp just after the MAF. Snugged that puppy down, cleared the engine light and it's been good to go since then. Just over a month now.

 

I had noticed that mine was loose as well, tightened it up and it's still persisting. I'll have to take another thorough look. 250km/tank is not a great time.

 

It is more likely there is a leak after the MAF allowing unmetered air into the intake, or that the snorkel has introduced turbulence causing the MAF to not properly meter the flow*--there is no "ram air" effect at speeds of less than 225 mph--more about that here...

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* - MAFs measure just a small sample of the total flow through them, and report total flow based upon that and assumptions of the total flow's charcteristics. A screen placed in the MAF inlet can often make the flow more laminar--Ford used such a screen on the V8 "new edge" Mustangs.