92 civic dx with d15z1-p07l01 with d16z6 harness no egr only getting 35mpg
 

Ok well i have a 92 civic dx with dx trans d15z1 p07l01 cali ecu d16z6 harness no egr other than that all stock dx but i deliver pizza amd im averaging 35 mpg for about a month i was rilunning without the vtec harness and averaged exactly the same and when i put the harness on i couldnt tell much of a differance with the vtec i cant hear nor feel it at all i understand its not like other vtec in that sense but the cel went off but no noticeable differances i was expecting atleast 40mpg any help would be greatly appropriated

The z1 operates in 12 valve mode until vtec engages which makes all 16 valves open. It only effects performance

The egr valve controls lean burn.