Converting your B18A1 OBD0 engine to OBD2 can seem daunting, but with the right information, it’s a manageable process. Here we address some frequently asked questions to guide you through your conversion project.
Question 1: OBD0 Crankcase Pressure Box and Vacuum Lines
Original Question: The obd0 motor has a crankcase pressure (or something) box on the back of it, is that going to hurt anything if I don’t run those vacuum lines to anything??
When dealing with the PCV (Positive Crankcase Ventilation) system during your B18a1 Obd0 To Obd2 Conversion, you have options. The OBD0 engine features a black box, part of its crankcase ventilation system, typically located on the back of the block. For your conversion, you can either retain the OBD0 PCV system entirely, ensuring all vacuum lines are correctly connected, or you can simplify things. If you opt for simplicity, you can plug off the black box and instead utilize your OBD2 valve cover and PCV valve setup. Choosing to ignore the vacuum lines from the OBD0 box without proper management could lead to incorrect crankcase ventilation, potentially affecting engine performance and emissions.
Question 2: Extra Sensor on the OBD0 Block Near Oil Filter
Original Question: The obd0 motor also has a sensor on the back of the block beside the olil filter that the obd2 motor doesn’t have, think it’s like a knock sensor or something, is that going to affect anything??
The sensor you’re noticing near the oil filter on your OBD0 B18A1 engine block, which is absent on OBD2 engines, is likely a knock sensor. For your B18A1 OBD0 to OBD2 conversion, this sensor is not critical for the OBD2 system to function correctly. You can safely leave this sensor in place on the block and simply not connect it to anything. It will not negatively impact your OBD2 conversion or engine operation as the OBD2 ECU will not be looking for or utilizing this particular sensor.
Question 3: OBD2 Plug Near Crank – Crankshaft Position Sensor
Original Question: The obd2 motor has a plug by the crank that the obd0 motor doesn’t have (think it’s like a crankshaft position sensor or something, not sure though) is that going to make the car run weird and throw codes if it’s not plugged in??
You’re correct in identifying the plug near the crank on the OBD2 engine as the Crankshaft Position Sensor (CKP). This sensor is crucial for the OBD2 engine management system. When performing your B18A1 OBD0 to OBD2 conversion, to properly utilize this sensor, you will need to swap over specific components from an OBD2 engine. This includes the OBD2 oil pump, lower crank sprocket, crank pulley, and timing cover. These OBD2 parts are designed to accommodate the crankshaft position sensor. Without this sensor correctly installed and connected, your OBD2 system will definitely throw error codes and the engine may not run properly, or at all. Since you’re undertaking this conversion, it’s also an opportune moment to replace your front seals, which are relatively inexpensive and readily available from Honda.
Question 4: Engine Harness Plug Diagram
Original Question: Where can I find a diagram telling me where all the engine harness plugs go on the motor, because I took the harness off the old motor to put it on the new motor, and didn’t even pay attention to where anything went… lol
For simplifying the engine harness connections during your B18A1 OBD0 to OBD2 conversion, it’s generally recommended to use your stock intake and exhaust manifolds. By doing so, and with the possible addition of a PCV hose routed through the manifold to the OBD0 black box (if you choose to retain it), most connections will be straightforward. Almost every plug will have a unique connector shape that only fits its designated sensor or component. The main areas where you might encounter interchangeable plugs are the TPS (Throttle Position Sensor) and MAP (Manifold Absolute Pressure) sensor connectors. If you experience codes related to these sensors or if the engine runs poorly after the conversion, try switching the TPS and MAP sensor plugs. Often, this simple swap will resolve any misconnections and get your B18A1 OBD0 to OBD2 conversion running smoothly.
