Lambda negative percentages?? Running Lean, Stumbling, Trims all over the place....

[PierceS4]

Hey guys so i understand lambda and how that works. But I don't understand why my car is running super lean and then when I use vcds it gives me a negative lambda percentage. How do I interpret that? And why would the readings from bank 1 to bank 2 be so different.

Check out the log reading below

[PierceS4]

Address 01: Engine (8K5 907 551 F)

16:09:16
IDE00597 Long term adaptation of mixture formation bank 1 16.4 %
IDE00598 Long term adaptation of mixture formation bank 2 3.1 %
IDE00604 Short term adaptation of mixture formation bank 1 -4.7 %
IDE00605 Short term adaptation of mixture formation bank 2 -4.7 %
Saturday,07,April,2018,16:15:49:56854
VCDS -- Windows Based VAG/VAS Emulator Running on Windows 10 x64
VCDS Version: 18.2.0.3 (x64)
Data version: 20180212 DS287.0
www.Ross-Tech.com


VIN: WAUKGAFL8DA069740 License Plate:


Address 01: Engine (8K5 907 551 F)

16:15:44
ENG102144 Lambda control value: bank 1 -7.347 %
ENG102393 Lambda control value: bank 2 -0.848 %

[95blkmax]

large correction gaps between banks can be caused by faulty O2s, OR a problem with the fuel system. I'm assuming you're taking these readings from the primary lambdas, so clogged up catalytics wouldn't be a factor.

Could you tell us what car and engine you have so we can better try to help you?

[imnuts]

What vehicle do you have? Did this just happen, or was it something that has progressively gotten worse? Did you have any work related to the fuel system or around the O2 sensors done recently?

Sent from my Pixel 2 XL

[PierceS4]

It's a 2013 Audi S4 and yeah I've replaced all the O2 sensors and injectors, plugs, fuel pressure sensor fuel control module, fuel filter, and I cleaned the hpfp but I haven't replaced any of the pumps. I have an aftermarket crank pulley and supercharger pulley and I'm running the EPL stage 2 91 tune

[PierceS4]

The problems started when I switched to the E85 tune but remained when I switched it back to 91 and have been getting progressively worse. It stumbles on acceleration and misfires but doesn't throw misfire codes

[PierceS4]

I also have the Autotech upgrade for the hpfp

[imnuts]

Are you certain you switched from one tune with issues back to the one without? When you switched tunes, did you switch fuel as well and get most of the E85 out of the tank and refill with regular gas?

Sent from my Pixel 2 XL

[PierceS4]

Yeah I ran both of the tunes without problem before and yeah I drained the tank before starting on the new tunes