Parts for your 1991 Mitsubishi Pajero-Crank angle sensor

1991 Mitsubishi Pajero crank angle sensor: what’s fitted and what to service

Based on factory and aftermarket technical references — Mitsubishi Pajero/Montero Factory Service Manual (1991, Engine Electrical), Mitsubishi 6G7x Ignition System training docs, and Haynes Pajero/Montero 1983–1996 — the 1991 Pajero may or may not use a crank angle sensor (CAS), depending on engine. Petrol EFI models (notably the 3.0L V6 6G72 and EFI 4G54) use a crank/cam angle sensor that’s built into the distributor. Some carburetted petrol variants use a magnetic pickup in the distributor that serves the same timing role. The common 2.5L 4D56T diesel of that era is mechanically governed and does not use a CAS because injection timing isn’t ECU-controlled. So, for a 1991 Pajero, a CAS is relevant for petrol distributor-ignition models and generally not used on mechanical diesels.

On petrol EFI 1991 Pajeros, the crank angle sensor is the quiet hero behind smooth running. Sitting inside the distributor, it feeds the ECU precise engine speed and position signals, so the computer can fire the coils and injectors at the right moment. When it’s healthy, cold starts are easy, idle is tidy, and fuel economy stays on song. When it’s crook, expect hard starting, misfires, random stalls, a dead tacho flicker, or a no‑start with no spark. Old Mitsu OBD1 systems can also throw ignition reference fault codes when the signal drops out.

Servicing is pretty straightforward. Under the bonnet, keep moisture out of the distributor, and replace a weeping distributor O‑ring so oil doesn’t contaminate the sensor. On optical types, a gentle clean of the shutter wheel and sensor window with electronics cleaner can restore a weak signal. On magnetic reluctor styles, check for rust buildup and ensure the air gap matches specs in the workshop manual. Always inspect the plug and loom to the ignition power transistor/igniter — cracked insulation and brittle wires are common on vehicles this age.

Replacing the sensor or the distributor assembly is a driveway job for a careful home mechanic. Mark the distributor body and engine before loosening the clamp so base timing isn’t lost. If the distributor must come right out, set the engine at TDC on cylinder one and refit on the same tooth. After any replacement, verify base timing with a timing light per the FSM procedure. Use quality parts (genuine or reputable aftermarket), and if in doubt, have a spark specialist run a scope check — it can spot a weak sensor long before it strands the vehicle.

Where is the crank angle sensor on a 1991 Pajero?

On petrol EFI models it’s integrated inside the distributor under the cap and rotor. There isn’t a separate sensor on the front of the engine. The 2.5L 4D56T diesel of this era generally doesn’t have one, as fuel timing is mechanical.

What are common symptoms of a failing crank angle sensor?

Intermittent no‑start, sudden cut‑outs, rough idle, misfires, and a tachometer that flickers or drops to zero are classic signs. The ECU on EFI petrol models may log an ignition reference fault. Heat soak problems after a hot shutdown are also common.

Can it be cleaned, or does it need replacement?

Light cleaning can help if contamination is the issue, especially on optical sensors. If the signal is erratic due to internal failure or a cracked pickup, replacement is the fix. After any distributor or sensor work, confirm base timing with a timing light.