crx si from canada eh.... bad mpg
 

anyways i got a 1990 crx si which i swapped a jdm doch zc engine in a year or so ago. i never really looked at my mpg before or after until now that i came across this site. anyways i calculated my mpg from a long 300+ km highway trip and came up with 22mpg which really sux cuz i got 420km total on the tank of 45 liters. i was reading briefly on this site, would changing my
o2 sensor increase my mpg? cuz its possible that its the original sensor ( the previous owner did very minimal maitnance to the vechile). also any other tips on increasing my mpg? :thumbup:

How fast were you driving?

With that kind of MPG, I would give the engine a full tune up, including 02 sensor, that engine isn't particularly inefficieny. What transmission are you using?

i was driving 100-120km/h not stop and go i dont really push the car i drive very fuel effecientcy (sp) aware. its a si transmission

hmm. That is really strange that you only got 22mpg. Was it really cold while driving? My Geo Metro showed 24mpg @ 65mph when it was -40*C/F with the windchill.

By the way, welcome to the site. Your car looks very nice!

-20 to -25 c maybe
originally from toronto area now living in north bay ontario temporarily, making quite a few trips back and forth.

Yeah, cold and wind can definitely be giving you those low numbers. I still wouldn't hesitate to go over the car with a fine comb though. Check out the forums about increasing fuel efficiency and make sure stuff is up to snuff. He hehe, it rhymes!

Higguns -

Welcome to GasSavers. Don't know what is wrong. Sorry. How many horses does a "jdm doch zc " have? Is that the same type of engine as the original SI?

Beautiful CRX.

CarloSW2

the dohc zc should have a four wire o2 sensor... I think. I've also been told that a few JDM engines used a single wire o2 sensor, but I think that's rather rare.

a new o2 sensor could really help, but I agree with SVOBoy and think a full tune up is in order.

I would say that it's your oversized ZC engine that is giving you a bit of the low MPG, I know a number of people who have or used to have the crx SI, and they alwas got close to 40mpg with it with the stock engine, but you did a swap.
If you put in a "full flow" exaust, you are most likely hurting your mileage, and power, same thing with the short air intake, as they have a tendency to de-tune your engine so it has a very narrow range that it runs efficently at.

Welcome to Gassavers. I don't know how much of what is affecting your mileage, but it sounds to me like it is enormously low, for that car, even with an engine swap. I'd definitely do an O2 replacement, new spark plugs and so forth. Additionally, if you did go with a full flow exhaust, you should consider switching it back to stock. For some reason those full flow exhausts seem to really kill the mileage.