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!

 

Hmmmm..... interesting...
Has it done it since only since the new motor?
Have you checked the timing and are the injectors correct for the motor and application?
Also, have you done a compession and leakdown test?

 

I bought the car with the swap so i got stuck with someone else's problems I suppose...
I did a compression test, I cant remember the exact numbers but they were even across the board. The engine is strong I know that, it doesnt burn any oil or smoke or anything like that...
I had a mechanic check the timing and it was correct.

The only thing i can think of is the fact that the fuel return line never has any fuel in it even after I turn the car off and pull the line....I also havnt tried changing injectors yet....arent all honda injectors 240cc or something like that?

 

looks like we have a problem... hmm

 

possible fuel pump relay going bad. and only b series injector are all 240cc.

 

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???

 

IACV has zip to do with your issue. For starters, I'd verify ignition and cam timing, dont just take some mechanic's word for it. Is there a catalytic converter installed? If so, unbolt and check to see if its plugged.

Careful with swapping TPS sensors. You can actually cause more problems if you dont set it correctly. Stop throwing parts at it!