Heres the story. I have a 92 Hatch DX. Before i did the engine swap, sometimes, mostly on a hot day, i start the car, it idle then it stall out. I figure I just hold off until i can get my engine swap. So, now i have my new engine in. Its a OBD1 B18b1. Now the idle fluctuates, even when I have adjusted it. And on hot days, it always stalls out. When I turn the car on it idles high for about 5 secs, this is from stop and go traffic, then drops a good 400 rpms. The stalling part is what is confusing me the most. It is exactly what the car was doing when I had my Stock DX engine in. I have replaced, spark plugs, wires, distributor car and rotor, O2 sensor, Fuel Filter, Fuel Pump, ran some fuel system cleaning in for the hell of it. I would like to know everyones opinion on the situation here. Could it be a coolent system problem that is causing the stalls? More sensors? BTW, fuel pressure never drops, and there are no codes throwing. Any ideas?

 

you check your thurmostat?

 

Are you using the original alternator?

Sometimes a bad alternator can cause an rpm drop and/or stalling. Honda uses what it calls an "FR" signal from the alternator to the ECU. If this signal is missing or screwy, the car will drop rpm's and/or stall on decel or at idle.