JDM h23 engine troubles

I recently brought a used 93 Prelude H23. I blew the engine and replaced it with a JDM H23 (about 30000miles). I did the install myself and all looks well but here is the problem. The car has a big hesitation when it is coming off of the line. If the AC is on it won’t stall out but the car won’t move. The car is also eating gas about 13mpg 200 miles to a tank. I replaced the whole ignition system (Distributor cap, wire, plugs, and rotors) still no better. And the vacuum lines are routed correctly. Anyone have any thoughts on what the problem might be?

hmm...

when your in neutral and rev the car - is there any lulls? or is it a smooth powerband?

I may be way out in left field - but I'm thinking perhaps it doesn't have to do with the engine but with a slipping clutch? - that would perhaps explain the large fuel consumption. (ie: your engine is delivering more than is being delivered to the pavement) are your revs higher than usual under all driving conditions? - of course if your car is automatic - it can't be that at all.

since you seem to have covered ignition... the remainder of my thoughts would be with either air or fuel, or finally poor compression giving lack of low end torque (was the jdm you purchased compression tested?)... make sure your intake is free of any obstructions/clean filter etc. also if you can or have available a pressure gauge - check the fuel pressure being delivered, correct me (someone) if i'm wrong but i believe the fuel pressure should be somewhere from 33psi to 43 or soemthing like that. Is it possible the fuel rail, injectors, filter or any other fuel component became contaminated during the swap?

finally did you use the intake manifold off your old engine ? are you sure the jdm you bought has the 240cc injectors instead of the 345cc h22a injectors?... or eh hem, is the jdm h23 you bought a vtec model? i think japan had h23 vtecs or something.

that's all i got for now... more clues might help... any cels?, noises?, what does the car do in neutral when revved etc.

Thanks for the detailed response looks as though you have covered my problem from several angles that I hadn't looked at. I forgot to say that the car was an automatic. It idols smoothly and revs with a slight hesitation in neutral. I only get one strange noise and it’s at high sustained speed I get a loud deep sucking noise from time to time like a lot of air being pulled through a funnel but only some times. I brought the engine from ASAP motors out of Houston TX it was supposed to have been compression tested by them but I didn’t do it myself. I believe the air system is good it has a new air filter and all of the vacuum lines are ran right. It is possible however that fuel stem my have been contaminated the filter is good though because I changed it. I will have to check the pressure at the shop. Your right I did take the intake manifold off of the old engine as far as the injector they are the injector off of the JDM engine. I have no idea if it is a VTEC. Thanks I’ll try your ideas this weekend.

you'll know whether you got vtec h23 or not b/c the engine swap for a jdm h23 vtec is about $3500 to $4000