wow ill try to kept a long story short. my 97 hx died after 260k. i got a new used egine from jdm engine corp. the motor runs great, but i got the sohc DUAL v tec. i put on a header and exhaust. i replace the stock cat exhaust manifold cause its hard for my ac condser to cool down. i heat wrap the headers and the ac blows cooler. i live in tx it gets real freakin hot here. i make 24mpg hwy and the only code i throw is cel 45 (p172) runs too rich and my rear bumper is black. got a fuel regulator turned it down to 18psi, stock psi read 28psi, still too rich and now i make 26mpg hwy "ppl" say because i free up my exhuast, there is more air flow from the intake, thus the map sensor is reading more air, thus letting more fuel being injected. can this motor be fuel efficient? did the aftermarket exhaust sys effect it that much? so im thinking of raising the fuel pressure to stock and installing a apexi neo afc to trick the ecu on map inputs. do you think this method will acheive 40+mpg? thanks guys

 

The HX motor is one of the most fuel efficient motors with it's VTEC-E system.

 

nope ive had more upgrades then this and never had a car run rich enough to blackn my bumper. i would say do the tune up. plugs. wires. cap. rotor. also make sure the timing is right. check for vacuum leaks. also replace air filter

 

Don't forget fuel filter! Helped my MPG a lot.

 

you should be able to get 40 stock.

why are you messing with fuel pressure? stock is supposed to be 38-46 with the vacuum line disconnected. put an oem regulator in good working order back in. i would first do a tune up (oem fuel filter, distributor cap, rotor, ngk plugs). if it still is crappy, i would go and replace the 5 wire o2.

 

i did all that (tune up) but i figured it out, it was the injectors. but thanks guys

 

nice find. mine actually started feeling boggish today did a balance test with fuel pressure and injector pulse tool and found two of my injectors were staying open longer then the others thanks to this video http://www.youtube.com/watch?v=ZnFSUNjwDPQ&feature=plcp

http://www.youtube.com/watch?v=85nMC6xIfUg&feature=plcp

pretty expensive tool buts its worth it

 

the orignal hx motor had a green color tip injectors. the new used motor that was shipped to my house had a brown tip injectors. well i had my fuel pressure set at 18psi and when i replace the injector with orignal green ones, the motor barely ran. i put my fuel pressure back to stock and now the car runs good. i took it around the block and the exhaust even sounds different, it sounds more raspy. between 1500 to 3300 rpm it use to feel boggish, but it pulls nice through the rpm band. i have a long drive tomorrow and we'll see how the mpgs go. i keep you guys posted. i hope i can get 40mpg.

 

@kyden a oem fuel filter? i use honda oil filters, but is there a difference with fuel filter too?

 

uuuggh raspy? you mean like a fart can? like this http://www.youtube.com/watch?v=c63alXgdGtY

 

lol no not like that