my crx hf is running to rich i have a d15b2 bottom end and head with hf manifold it constantly throws a code 1 for o2 sensor . i replaced the sensor with a shitty bosche one and im not sure why it keeps throwing the code forcing it into open loop and getting terrible mileage like 25 mpg
help please

 

you sure it's not leaning out due to the larger motor causing the code and fail safe pig rich?

 

D15B2 and D15B6 have the same size bottom end (1.5ltrs) so its not a bigger motor. It might be due to you running a 16 valve head on a 8 valve ecu (pm8). Try a pm6 si/ex ecu and go from there. Your o2 code is most like due to your egr and causing your poor mpg, every HF I've owned I've had to clean out the egr passages or I would constantly get o2 codes. Leaning more towards your egr passages being the real problem, not the ecu.

 

il try a pm6 ecu n see if it cleans up everythign and clears the code

 

tried a pm6 and it cleard up the o2 code