B16A Engine Swap into a Second-Generation Honda CRX (ED9)

Drain all remaining fluids from the front cut. Remove the radiator and battery holder, and disconnect the heater hoses at the engine side. Unplug every engine-bound wiring loom connector at both shock towers. Undo the power steering hoses at the pump, the fuel lines and vacuum lines, and the throttle and clutch cables. Free the starter motor wires along with any earth leads between engine and body. Unbolt the MAP sensor and the fuel pressure regulator solenoid. Confirm the air conditioning system holds no refrigerant - if it does, have it evacuated professionally - then undo the A/C lines from the compressor. From underneath, undo and remove the shift linkage, then remove the driveshafts and hubs. Undo the engine mounts at the front and rear (those attached to the front and rear crossmembers) so the engine hangs from the gearbox mount and the front-of-engine mount. Secure the engine to an engine hoist, undo the remaining mounts, and carefully lift the engine out. Strip everything else from the front cut without damaging it - many parts are needed for the install and the rest can be sold.

Strip the dash out of the front cut to expose the cabin wiring loom hiding behind it, and remove the complete loom. Do not cut it - the loom must come out intact because a connector and its wiring will be transplanted into the CRX loom later.

Drain all fluids: power steering, engine oil, gearbox oil and coolant, and have the air conditioning degassed by a qualified air-conditioning shop. Remove the battery, battery holder and radiator, and disconnect the heater hoses at the engine side. At each shock tower, unplug all the wiring loom connectors that feed the engine, leaving the injector resistor box in place in the engine bay. Unhook the speedo cable, the power steering high- and low-pressure hoses at the pump, the fuel high-pressure and return lines, and the vacuum line to the brake booster. Disconnect the throttle and clutch cables, the starter motor wires and all engine-to-body earth leads. Unbolt the MAP sensor and the EVAP purge solenoid, and undo the A/C lines from the compressor once the system is confirmed empty. From underneath, detach the shift linkage at the gearbox, take out the driveshafts, and split the exhaust between the downpipe and the catalytic converter. Undo the front and rear engine mounts on the crossmembers, then remove the front crossmember and undo the castor rods from the lower control arms. Secure the engine to the hoist, undo the remaining mounts, and lift it out.

Prepare the B16A before installation - everything is far easier with the engine out of the car. Fit a new timing belt, adjust the tappets (valve clearances) and check the water pump. Renew the clutch as well if desired; in this conversion only the timing belt, water pump check and tappet adjustment were done.

Attach the side engine mount at the engine's front (timing belt end), using a nut and bolt in the left hole and a nut with several washers on the right - the washers matter because the thread stops partway along the stud on the engine. Leave the rear crossmember mount off for now; there is no front crossmember mount with these mounts. Lower the engine in gearbox-end first so it passes beneath the chassis-mount bracket for the gearbox, then align the front (timing belt side) mount with the chassis mount and fit its bolt temporarily, then raise the gearbox side, fit the gearbox mount and slide its bolt in. With the engine hanging on the two side mounts, check everything: the D16A8 clutch and throttle cables do not match up (use the EF8/EF9 cables); the EF9 uses a VSS rather than a cable speedo (resolved later at the gearbox); the heater-tap hose fits, but the hose direct from the heater core at the firewall is very tight and should be replaced; the B16A high-pressure fuel line fits perfectly; the power steering high-pressure hose does not line up (swap to the EF9 hose); the shift linkage from the D-series will not fit; the power steering pulley touches an A/C line - lever the line clear gently with a large screwdriver; the exhaust will not line up and needs an exhaust shop. Check the alternator pulley clearance to the chassis and mark the chassis at the high spot, then temporarily fit the A/C compressor and mark its tight spot the same way.

Remove the B16A from the car. Remove the CRX's high-pressure power steering hose and install the EF9's high-pressure hose in its place - one 10 mm bolt on the crossmember plus the nut hiding beneath the cover on the rack itself; note the EF9 hose carries a pressure switch. Swap the shifter: remove the shift knob, undo the centre console screws and remove the console, unbolt the D16A8 shifter from under the car (two 12 mm bolts), pull it out and fit the B-series shifter from the EF9, then refit the console and knob. Using the marks made during the test fit, gently hammer the chassis where the alternator and A/C compressor pulleys run close. On the Y1 gearbox, remove the VSS and its pickup (one 10 mm bolt), then take the cable-speedo pickup off the D16A8 gearbox and transfer it onto the Y1 in the same orientation, lubricating the seal with oil - it fits and works, restoring the cable speedo.

Remove the CRX ECU (four 10 mm nuts under the carpet in the passenger footwell) and place the donor cabin loom on a bench. Conventions used from here on: the engine-bay connector transplanted from the EF9 loom is the engine bay B connector; the matching connector on the right-hand side is engine bay A; pins are numbered viewed from the wire side of the connector, pin 1 at top left, running left to right along each row. Locate the left-hand-side engine-bay PGM-FI connector - the round yellow 14-pin connector found on the LH shock tower next to the injector resistor. Split it from the loom: carefully cut away the tape and conduit from the connector back to the rubber grommet, then continue stripping tape and conduit the whole way back until you reach the ECU connectors. Trace each of the connector's wires back to the ECU A connector and release them one at a time by pressing the plastic lock tab in the connector while pulling the wire out. For the ECU B and C connectors, unclip and pop out the locking plate, then press a small strong pin (a small drill bit works) into the middle hole at the end of the connector, push up into the terminal and gently pull the wire to release it. Six wires will still tie the connector to the loom - cut these as close as possible to the ECU connectors: B12 (yellow, VSS power), B13 (yellow/red, VSS signal), B6 (yellow/black, to PGM-FI relay), B7 (yellow/black, to PGM-FI relay), B14 (black, ground), and the black power steering ground.

With the front mount still fitted tight, loosely fit the rear mount (the one that bolts the engine to the rear crossmember housing the steering rack), then install the engine exactly as in the test fit and tighten the two side mounts. Check the rear mount against its holes in the crossmember: if it lines up, fit its two bolts, bolt it down and tighten the through-bolt; if not, loosen the metal bracket at the gearbox, bolt the mount to the crossmember first, then tighten the bracket. Reconnect everything: heater hoses (the heater-tap hose fits; replace the firewall hose - a cut-down D16A8 hose works); speedo cable with its gold lock retainer; power steering low-pressure then high-pressure hoses; EF8/EF9 clutch and accelerator cables in place of the D16A8 items; the B16A's MAP sensor and its fuel-regulator cut-off solenoid onto the firewall; EF8/EF9 brake booster vacuum tube and hose; fuel main and return lines (they reach and line up without problems); and the positive battery lead to the starter motor. Next plug in the PGM-FI A connector plus the two other RH shock tower connectors, then the PGM-FI B connector on the RH shock tower and the injector resistor. Fit the EF9 radiator - the ED9 radiator's hose necks are too small - swapping the fans between the fan housings so the fan connectors do not need rewiring; connect the hoses and fans. Refit the battery bracket, intake pipe and air cleaner, and the earth leads from gearbox to chassis and rocker cover to body. Underneath, connect the shift linkage to the gearbox and refit the front crossmember. Note the A/C compressor sits too low to clear the front crossmember - HAsport make a bracket that lets the D-series compressor clear it; in this build the compressor was left off pending that bracket.

Six cut wires remain on the transplanted B16A engine bay B harness. 1: black with a single silver dot (this is ground, running to B14) - tap-solder it onto the ECU A2 black wire (do not cut the A2 wire), tape the joint, then confirm continuity from B14 to ground. 2: black with two silver dots (power steering pressure switch ground) - tap it onto the ECU A4 black wire, tape it, and confirm continuity to ground from the power steering pressure switch's black wire. 3 and 4: the two yellow/black wires (main PGM-FI relay and ECU) - solder both together and tap onto the ECU A15 yellow/black wire, tape it, then confirm continuity from B6 and B7 through to ECU pins A15 and A13. The remaining yellow/red and yellow wires belong to the B16A loom's VSS connector; the cluster VSS is already wired because the car keeps its cable speedo, so simply tape these off. Next run a shielded twin-core wire between the engine bay A connector and the ECU: fit each conductor with a soldered terminal and plug them into engine-bay pins A4 and A8 (A4 holds the old TPS pin - remove it, chop off the pin and reuse the terminal). At the ECU end, take the terminal cut from ECU B4, solder it to the wire from A8 and plug it into ECU B19; solder a spare ECU B terminal from the B16A loom onto the second wire, which then plugs into ECU C8. Join the two shields together at the ECU end only and connect them to ECU A16 (brown/black) - shielded wire is mandatory and must be earthed at the ECU end only. Optionally, swap the two pins in the purge-control solenoid connector (now the fuel pressure cut-off solenoid) so the wire colours match - this has no effect on operation. Cut the pins off the leftover D16A8 loom wires and tape them up; they are no longer needed.

Confirm every engine-bay connector and sensor connector is plugged in, then plug in the ECU and connect the battery. Turn the ignition to position II: the cluster's MIL should light and then extinguish, the fuel pump should prime, and the ECU's internal LED should also light and then go out - indicating the ECU has found all its sensors. Turn the ignition off. Bring all fluids up to specification: coolant, power steering fluid, oil for the manual gearbox, engine oil, brake fluid and fuel. Cycle the ignition to II, off, to II, off to prime the fuel system, then start cranking. The engine will fire after a few good cranks; expect it to run roughly at first if it has not been started in a long time.