Rep Power: 0

As the title states I have a 96 spec JDM ITR complete swap in my 00 civic EM1. The car has the obd2b to obd2a conversion harness with the matching p73 ecu. There are no check engine lights but the car has a terrible bog in the low range rpm.

It seem like you can floor the car in any gear and if the rpm is below 4 grand the car has absolutely no power. I have mini vans passing me! The car pulls strong and hard in vtec though but it seems like I have to rev the hell out of it to get any power at all!

Im getting terrible fuel mileage as well! I have swapped FPR, ECT, plugs, wires, distributors, tps, IAT, map sensor, new fuel filter, swapped fuel pump, O2 sensor, no luck! I also did a valve adjustment too!

One clue is the car seems to have trouble starting also. It takes an extra half crank to start the car and it stumbles then clears! I have a fuel pressure gauge on the car and the fuel pressure drops from about 35-40psi zero after about 10minutes.... is this normal? I also hear a strange noise coming from the gas tank....? If i remove the vent to tank from the black charcoal canister the sound is very audible with the car not running it is makes a strange noise for about 3 seconds then goes away?

One more thing to mention is when swapping different things i tried my buddies FPR off his GSR and when i pulled the return line hose from his FPR it was full of fuel even though his car had been sitting for at least a month! Mine on the other hand was bone dry? Is it possible there is a problem with my Fuel return?

I have literally tried everything except swap the injectors! This thing is making me crazy!

Any help would be more than greatly appreciated!

 
Rep Power: 813

its very possible a fuel problem from what you describe. you may have clogged injectors or something clogged in the lines (or fuel filter needs replacement). have you cleaned out all the intake parts like idle and fitv valves and throttle body?

 
Rep Power: 0

Yes sir I put a brand new OEM honda fuel filter and I cleaned the TB with throttle body cleaner, cleaned the IACV and I even seafoamed the engine. Tried running fuel injector cleaner also with no luck....

Should my car be keeping fuel pressure even after turning it off? Because it bleeds to 0 after about 10minutes....Also the fuel return line not having any fuel in it seems a bit suspicious....

 
Rep Power: 813

it should yes. and all lines need to have fuel. thats prolly the issue you have with the car not starting right away (like vapor lock). do you have any leaks? is the gas cap good?

 
Rep Power: 0

There are no fuel leaks...The gas cap has been replaced with an aftermarket one...Another strange comment I will make is when im filling the gas tank at the station it sounds like the air has nowhere to go...As if when I fill the gas tank with gasoline the air is rushing back up the line and around the pump nozzle? Hard to explain but its like you can hear air coming back out of the tank when you are filling with gasoline....Doesnt make this noise when I fill my s2000 or any other car....

 
Rep Power: 813

yeah something is wrong with the fuel system. and its really hard to figure out without taking stuff apart.

 
Rep Power: 0

Where do I start? One thing that came to my mind was the fact that I believe on this car there is an EVAP unit beside the gas tank under the car. My JDM ECU is essentially a OBD1 ecu so it no longer uses any of the emissions stuff...Is it possible there is some sort of electronic valve in that unit that isnt opening?

 
Rep Power: 813

yeah its possible. the evap system has alot of valves and solenoids. the system is actually quite complicated and uses hoses and valves to direct gas vapors back to the engine from the gas tank. and its on a cycle so ecu needs to open the valve for it to work. you really need to get a manual and see how the system is setup. im not sure what you can do tho unless you figure out how to disable the system.

 
Rep Power: 0

NEW UPDATE: Still having the problem...Tried running the car with the IACV unplugged from the ECU and the car obviously wont idle...But if I try to hold a steady rpm for example 3000 it will bounce up and down and you cant even drive the car partial throttle. Does this give us any more ideas as to what is wrong? Because even with the IACV plugged in the car is hard to drive in traffic and is very jerky. But with it unplugged the problem is amplified???