Hey guys not sure if this has been covered. I did a jdm b16a swap into an 89' honda crx si with a 37820-p30-000 ecu. I also have the rywire obd0-obd1 jumper harness. I had it working for a little bit then the fuel pump stopped priming when I turned the key to on position. I replaced the ecu with another one like it and then I was having a voltage issue. When I would put a load on the engine when driving the voltage would drop until I reached about 45 mph. As long as I was driving the voltage was fine, but once I slowed down the voltage would drop again. I put another ecu in and the voltage was fine and everything worked for about 3 days than my rpms would drop almost stalling the car. This happened a couple of times and then it went away, but now my rpms idle at 1000-1100 rpms when the car is all warmed up. I've already replaced the iacv, fitv, reman alternator, new battery and vacuum hoses. I put another ecu in the car and it idled fine, but the voltage issue was back again. I can't figure this out and was hoping ya'll might be able to. I was wondering if the rywire harness could be messed up maybe. the fuel pump is a walbro 255 high flow also.

 

Main relay possibly. That or you are getting some sort of ELD issue. Check your grounds. Seems like a weird issue all together. The idle could be a vacuum leak if you replaced everything already. Have you bleed the coolant system?

 

Have you tried setting the idle by the method described in the FSM?

 

yes I tried another main relay. Also changed out the fuse box with eld. Bleed coolant lines and set the idle according to the manual.

 

Have you checked the grounds and the wires that lead to them? Bad ground contact or worn wires will lead to unusual voltage drops.