Okay I have posted questions about this topic, but did not get any real answers. Right now I have an obd2 b18b1 in an ej1 ('94 civic ex), with an obd1 p75. I have the engine harness that came with the engine. For some reason the car revs only to 6200 rpm and gives about 17-18 mpg. I put in an automatic p28 and the engine revs to 6500rpms and gives about 20-21 mpg. The car is running and drives good other than those two problems and need help.

 

Do you get a CEL when running the OBD1 P75?

 

Try a PR4 or P7H ECU??

 

There aren't any check engine lights, which is why i am stumped.

 

I'll rack my brain on it a bit more, maybe RonJ will pop in. You are going through way to much fuel. I have a B18B1 in my 93 EJ1 and I average 35-36MPG and that's with the shorter geared GSR tranny over its long geared LS brother. 17-18 is WAYY off.

 

I have a b16 hydro tranny.

 

I have a 95 cx with the same setup. b18b1 with the integra wiring harness, obd1 p75 ecu, and car has no where near the power it should and burns gas like crazy too..

 

Wow, me and a buddy built a CRX with a B1 and it gets like 35-38 mpg and has plenty of power... even with 240K on it.

 

Mine to, I average 35-36MPG as I said above and mine runs like a champ with an OBD1 P75.

 

damn, maybe i need to switch my b16 out for a ls...any takers???







i kid, i kid

 

Did you guys chip the p75 or did you just plug it in as is?

 

My P75 is a Virgin.

 

I just plugged mine in too

 

does it really matter if the ecu is a canadian ecu vs an american one?

 

No it shouldn't. I have a simliar setup, 1994 B18B1 running virgin canadian P75 and I get 35+mpg and has expected power with LS trans.
Are your ecu's 5 spd or auto? Was your engine from a 5spd or auto car?
I've got a virgin OBD1 PR4 5spd ecu if interested.
Are all sensors hooked up correctly and known to be good? Especially the O2 sensor?
Correct spark plugs, wires, etc?

 

Well my car was an automatic that I converted to manual. It still has the neutral switch (the little white piece that connects to the bottom of the shifter). The computer itself is a manual p75. One of the things I don't understand, I had an ls vtec and a virgin automatic p28 ecu with the intake/exhaust and neutral switch and got 24-25 mpg and that was on the lean side.

On my current setup you can actually tell the car is running rich and also won't go past 6200rpms

 

Is the ecu known to be good? Can you swap in a known good P75 or PR4? Hows the fuel pressure? Ignition system? Does it idle fine and just cut out at higher rpm? Have you changed the O2 sensor with a known good one?
Obviously something is wrong, but it's gonna be hard to narrow it down.

 

It just cuts out like it hit the rev limiter, the ecu I got off of ebay. The O2 I know is good.