I run the STS rear mount 8psi...Car is suddenly running lean at idle and cruising speeds..system uses UTEC. AF ratios under full boost are 10's to 11:1 (happy with that) but highway cruise in 6th at 70 mph is 17 + :1 and idle is 16 to 17:1. I have a two day race this weekend I can't miss or I will loose first place standings for the season. I NEED HELP NOW. Thanks- Jim

 

add fuel, adjust your 0% column only.

 

^

you may also want to look into what caused the sudden change to ensure it doesn't happen again or get worse during your race.

 

Any chance its just your wideband being stupid? Maybe recalibrate if thats an option on your particular model.

 

Goosegoose had the same problem way back then were he lean out (around 18-21 A/F) at 0 column but fine under boost. I think cleaning his Throttle body fixed it. See if reseting the ECU help too.

PM Goosegoose and here is his thread...

https://my350z.com/forum/tuning/313435-utec-tuned-sts-leaning-out-to-21-afr-on-low-map.html

 

Thanks AthenG...I'll clean out the throttle body today and see if it helps.
I'll also check the zero column but my car doing exactly what goosegoose car did. Thanks again. -Jim

 

make sure you dont move the throttle plate by hand unless its unplugged!