Help with Negative Fuel trims with stock 2016 Tahoe

[doseri]

hello all

i need your help to figure out why my car have negative fuel trim, my car is new model 2016 Tahoe ls z71 stock car 17000km only, i bought hp-tuners to tune it because i was lossing gas mileage !!!! and having rough idle!!!!

first time i did data-logging for it, i find out that the car have negative long fuel trims (bank1 -9% bank2 -7% in idle at 550rpm):bigshock , and 2 to 4 degree knock retard at 1800rpm to 2100rpm i attached the log file

i was thinking that i have dirty or clogged fuel injector but negative fuel trim

so any suggestion on how to address the issue with my car ???

:run 1.hpl ,

[5FDP]

Clean the MAF with MAF cleaner and reset the trims, see how they react over a day or two. See what they go back too. On a stock calibration anything within 5% of zero is pretty normal from what I always see.

Knock is normal, it's all stock, haven't seen one yet that doesn't show some knock from the factory. It's like they basically build the calibration with knock in mind and all those predicted knock tables. I bet if you ran some premium fuel (91-93 octane here in the USA) it would surely help reduce some of the knock.

[doseri]

Clean the MAF with MAF cleaner and reset the trims, see how they react over a day or two. See what they go back too. On a stock calibration anything within 5% of zero is pretty normal from what I always see.

Knock is normal, it's all stock, haven't seen one yet that doesn't show some knock from the factory. It's like they basically build the calibration with knock in mind and all those predicted knock tables. I bet if you ran some premium fuel (91-93 octane here in the USA) it would surely help reduce some of the knock.

doseri said:1 Minute Ago

Hi

Thank you for you info

I was thinking to cleaning the maf and throttle body and do reset for it

One more thing, the air-fuel command is 14.11?? Is it normal, I was thinking Mast by 14.7

Regards

[5FDP]

What's your stoich table set too?

I thought most of the newer trucks run 14.1 because most places run ethanol in their fuels.

[doseri]

What's your stoich table set too?

I thought most of the newer trucks run 14.1 because most places run ethanol in their fuels.

the stoick AFR table set to 14.10840 in the stock file

stoich afr.PNG

what do you think ???

[5FDP]

Then it's normal, that is just how they calibrate them from the factory.

[doseri]

Then it's normal, that is just how they calibrate them from the factory.

thank you