I have a 91 CRX HF with the D15B6 all stock besides a header, test pipe and a 2.5 inch catback exhaust. I have done a tune up on it that consists of plugs, wires, cap, rotor, and fuel filter. Just for ***** and gigs I unplugged the O2 senser to see if it would through a code, but no CEL, I don't know what else I could do besides a new O2 sensor. Any help would be GREATLY appreciated, thanks in advance guys!

 

pull the head off. i bet there is **** all over your pistons. i get 36mpg on my a6.

 

I can't really do any type of work like that bc this is my daily and I don't have any other transportation.

 

thats weird how you get 22mph. i honestly couldnt think of what it could be. maybe try cleaning your injectors?

 

Do you think an additive could do that?

 

this stuff does wonders it cleans out your injectors and stuff, just put it in your gas tank with a full tank of gas and I usually get 2-5 mpg better. Plus i believe it makes my car run a little better.

 

I'll give that a try, thank you!

 

maybe ur intake manifold is all gummed up try takin it off and clean that thing out with carb cleaner to the throttle body too put new gaskets of course and check lil things like timing and set ur idle and that will prolly cure that right up try it and let me know,im from milwaukee i travel to green bay to do work for a guy so i cant do some work for u if need be

 

Test your PCV valve. It will move freely when you shake it or if you blow it from one side, it will open but stay close on the opposite end.

Or test your injectors. One may be sticking open dumping fuel

 

Also check air system... good air filter, clean, etc...

New O2 sensor is cheap enough if you don't know when it's been done last. Check wiring if disconnecting isn't throwing a cel.

 

The air filter is brand new, the o2 sensor has 10,000 miles on it(previous owner told me)

 

i wouldn't try any fuel injector cleaner. Consumer Reports have tried just about every one on the market and all of them don't do much to improve mpgs that a simple tuneup wouldn't fix.

If I were you I would replace your 02 sensor. If it is bad it might be making your car run way rich which would cause the mpgs to go down obviously.

I have the same engine. I can't think of anything else that would be causing you to get such bad mileage.

 

Start with the easy stuff. Lift the car and make sure the wheels spin freeely.
I would suspect the injectors are flowing too much or even leaking internally.