Help! 92 civic cx d15z1 swap

[Onedopehatch]

So I bought this 92 civic cx from a buddy of mine for a daily driver. The motor and Trans had been swapped by the guy before my buddy. It gets around 35mpg combined (city/highway) and when I first got it I thought it was great gas then I started to look and it seems that the z1 should be getting well over 40 mpgs, so I started digging and looking through car more closely and found that it's running of a p05 but shouldn't it be operating off of a p07? Vtec isn't hooked up because It doesn't have a vtec ecu doesn't it mean it doesn't lean burn as well to save gas? Would swapping to a p07 fix the gas issue? I'm Nee to the whole ecomodding thing. I've done all of the maintenance on it and tire pressure and such. Any help is welcome, thanks

[Hicks]

P07 is what the z1 should be running off, depending on which p07 you get will let it lean burn (l01 or l02 I believe are the 2 different ones), either would help.

[Onedopehatch]

Do I need the wideband O2 as well for it to work properly?

[Farlander]

You are exactly right on both fronts. You need the P07 for vtec to engage, you would know if it worked because you would feel a distinct drop in power at light load cruising speeds between 45-65 mph at times. You also need the 5-wire air fuel ratio sensor for the d15z1.

[Onedopehatch]

Ok, if I switched to the p07 for a little bit then got the wideband O2 would the gas mileage increase with just the new ecu? Or will it run worse because it's missing the wideband O2?

[user removed]

The ecu needs the signal from the wideband (5 wire) sensor to operate a lean burn function.

regards
mech

[Onedopehatch]

Thank you!