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I am new to the Evo community and the forum as well, so please forgive me for my noob-ness and possibly posting to the wrong place.
I recently got my car back from the tuner, where they installed 1000cc injectors (FIC), a Tephra tune, AEM wideband and boost gauges. The first two days the car was fine, minus the occasional increase in AFR during idle. When idling, the AFR was at around 14.5 and fluxed upward to 16ish then back down to 12ish until it returned to 14.5. This didn't bother me much, as he said idle on the X's was difficult to stabilize perfectly. On the third day, the car stalled upon reaching a stop & the CEL turned on. The car starts back up no problem, but occasionally (I'd say 50% of the time) when I come to a stop the idle and AFR is jumpy, to the point where the car will go so lean it stalls, unless i give it some throttle. Under load the car performs great, its only during idle that I encounter issues. Its a 2008 Evo X GSR with 140k miles.
The code being thrown is P0133 1. Oxygen Sensor Slow Resp. (B1S1) 2. Oxygen Sensor (Front) Response
I just purchased the car this year so I don't have tons of information on previous modifications, but it appears to be relatively stock, minus:
-An aftermarket air intake (I have no idea what brand it is, there are 4 seemingly Japanese letters on it, I will attach an image below)
-1000cc injectors
-Tephra Tune
As I said I'm new to this, so please forgive any mistakes or information I could've left out!
If you have any idea as to the steps I should take to fix this please let me know! Thanks guys!
UPDATE: I replaced the front O2 sensor with and OEM Denso 234-4116 and it ran fine for about 30 minutes until code P0133 returned. It still leans out at ideal and dies.
Any help would be appreciated!
