"System too lean" Any suggestions?
 

Wishing a Happy New Year to Everyone!

Get messages P0171 (Bank 1) & P0174 (Bank 2) which suggests something like an air-intake leak common to both sides?

The fault occurs in cold weather, so I'm thinking maybe its a gasket leaking somewhere?

Any suggestions very much appreciated...

Could be air leak but also check fuel pressure along with looking at the fuel trims ST & LT to see what the ECU is trying to do about it

If possible take a look at the MAF sensor and see what the flow is at idle,

Neal

Thanks for the suggestions.

The fuel pressure side is complicated by my LPG conversion ( Liquefied Petroleum Gas) with the truck able to run on Gasoline or Liquid GAS (slightly confusing terminology)

As MAF sensors work on temperature differences and cold temperature cause the issue, this could be a a good call. I'll check it with the TECH2 and of course the ST & LT.

I'll report back to the forum with the results.

https://cimg5.ibsrv.net/gimg/www.hum...7be1124b6f.jpg
Air Intake Seal Issue
Well you were right, it most likely was an air intake leak (will need to wait for freezing temperatures to be 100% sure)

When I replaced the A/C compressor I managed to badly "kink" the rubber seal connecting the air-intake to the engine, looks like it would leak (see pic)

Thanks for the support!

when I bought my hummer it had the same kink in the same spot but it had not set a code.
I found it when I went to clean the MAF and throttle body since I did not know any history on the truck. but there is a TSB on our engines that require the orange intake gaskets be replaced with teal colored ones and also to check the intake plenum for square across a 200mm section of the intake runners. if it is warped more then 3 mm it should be replaced. the TSB is for lean/ misfire or hesitation when cold and might trigger a lean DTC