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Cobb N54 - AFR too lean in spool mode accelerati​on (short log and map attached)

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Hello all,

I have this strange problem with my Cobb N54 which puzzles me. I have full bolt-ons and RB turbos and using 91 octane fuel with no methanol and no e85.

I tuned the car myself for a 95RON (91 US) daily driver map, and everything works perfectly but I am worried about some AFR values. I have enabled spool mode (wasn't by default but I need these to fix the RB turbo lag) and left the "disable torque safety path" parameters checked, as default.

Basically, if I accelerate moderately, the car enters spool mode and this is great but the AFR values are much leaner than what I requested in the Fuel (spool) map. As you can see from the log, instead of 13.5-14 (requested AFR) the AFRs are 16-17. The STFTs look fine (to me).

If I accelerate more abruptly, the AFR values are correct most of the time.

Attached you will find two short logs and the IJEOS map that I am using (based on the Cobb Stage 2+FMIC Aggressive but with tuned WGDC, AFR, timing and load). One has a "good" AFR (mostly) and one has a "bad" AFR...

Any idea about this ?
Thanks !

PS: I did find a 29E0 (or 29E1) "fuel mixture control - too lean" code a few days ago. It happened at idle (800RPM) according to the BT tool. I could not reproduce that code again no matter what. No other error codes to speak of.


logs_map.zip
Attached Files

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