Shouldn't I be getting better MPG
 

My 89 Civic STD HB now has an 89 CRX HF California edition 5 speed. I drove around town a little and then to work and back and put on about 200 miles and got around 41 MPG. Was hopping for a little better but it still need an alignment. So I hopping that helps a little. The final drive is 3.25 witch is the same as the vx(I believe). so I am going to call it an 89 Civic VX. I also put in fuel injector cleaner because it would run rugh and die at stops every ounce in awhile(not all the time).Would the injector cleaner affect MPG badly?Could this be form a bad O2 sensor? Mine also dosent have v-tech. Dose that make that much of a diffrence. Mine is only a 1.5 Liter. Shouldn't I be getting better MPG.

Running rough and stalling out could also be a sign of needing a tune up or a vacuum leak. Have the plugs and wires been changed lately? Most people change their plugs at least every few years, but most people never think about the plug wires. If the car was in need of the injector cleaner it should have helped the mileage rather than hurting it, because it would have a better spray pattern. A bad oxygen sensor will really decrease mileage. I have had them go bad before and my mileage drop about 25-30%. I don't know much about Hondas so I don't know what kind of mileage you should be getting.

How about battery condition or alternator output? If that's crummy, it will affect things too. Ignition and everything requires and amount of power. Might just need the battery terminals cleaned.

Sorry, but if your 89 Civic STD HB has the original engine in it, it is not even close to being an "89 Civic VX". Why? Well, because the VX has a very special engine (the VTEC-E) and the whole vehicle is tuned for fuel efficiency. I'd say getting 41 MPG is pretty good. I'm sure some improved techniques could raise it, but the EPA MPG for your car is around 30 (mixed driving), so 41 is definitely higher. I'm sure the tranny is helping.

Note that the CRX HF also had a slightly different engine (D15B6) and better Cd.

Hey, some of us would be THRILLED with 41MPG. When my car is working completely right, I get 31.

Ah, but if the car was in need of professional injector cleaning or injector replacement, injector cleaner could just exacerbate the issue by loosening the gunk long enough for it to recombine into a worse obstruction or just a different shape with a worse spray pattern.

The VX engine has lots of economy features not present on other engines, such as lean burn mode.

the alignment can have a big impact on the FE if it's your toe that's out. caster/camber have a lot less impact on it since they don't cause the tries to be dragged sideways across the pavement.

One time when my car was dying sporadically it was due to a plugged fuel filter.

I've had two different EF standard hatches, a 91 and an 89, and with the original transmission they would consistantly get 34-36 mpg without any hypermiling techniques or mods. You should be pretty happy with 41 if you're driving normally.