Elpecoso

I have a 93 honda eg with a b20b4 block & b18b1 head swap(non vtech)(got a good deal out of both so i put it on the eg) little more info into this. I kept my single cam harness from d15b7 & bought the adapters for the distributor, alternador & ecu to use with the harness. My ecu is a virgin p75-a03 from a 96 integra. When I turn my car on after a minute or so it loses power close to turning off or at times it completely dies. My question is having this engine setup, was I supposed to chip & tune my ecu? Could that be the problem?... I did a vacuum leak check around too & found out the intake manifold & throttle body gasket were bad so I replaced them, but still nothing... Any help or suggestions?????

PyroProblem

Could be. There's a ton of things that need to be checked when trying to diagnose power loss. Try the ecu tuning or sub forums. This section is more for engine assembling and machining.

EH3_Jacob

A few things to consider:
If you put a head from a different motor on another block, usually you should get the head and block taken to a engine shop to be decked, etc.. Reason for that is, the head wouldn't seat on the block right. Also you might have a new compression ratio, so check the compression.
Distributor - Position (Timing), Rotor button and cap, coil (could cause weak ignition)
Plug adapters - Depending on where/who you got them from, maybe they are faulty?
O2 sensor - The motor ECU is ran off the Air/Fuel Ratio, if you don't have one, a chipped ecu should take care of that (disabling the o2 sensor)
ECU - Try another ecu
Sensors - Make sure all the sensors are in the right place, I've personally gotten the IAC and TPS mixed up
Battery - Are you getting proper power?

Elpecoso

Today i replaced the spark wires, 3 of them werent throwing sparks. I checked the spark plugs on the distributor side & they were giving out sparks so i don't think the distributor is bad. After i set my engine back to TDC incase the timing was bad or my timing belt was lose. After all of that i turned it on & it was better, but after a while it started idling strange going from 800 to 200 & back up. I took out the iacv & flushed it with carb cleaner again too se if any miracle happens smh.

EH3_Jacob

Ah, the good ol` IACV. Sounds like it`s going bad. Usually it`s the cause of what me and my friends call "Honda-syndrome", where it sounds like the engine is pulsing or surging when trying to idle. If this is happening in your situation, i'd look at replacing the IACV entirely.
Another issue could be your fuel. Is it old? supreme? Maybe contaminated? Injectors?
Good luck to ya.