Parts for your 1988 Mitsubishi Pajero-Throttle position sensors

1988 Mitsubishi Pajero throttle position sensor (TPS): what’s fitted and how to look after it

Technical references show the 1988 Mitsubishi Pajero may or may not use a throttle position sensor, depending on the engine. The Mitsubishi Pajero/Montero Factory Service Manual (1988–1991) for the ECI‑Multi fuel‑injected 3.0‑litre 6G72 V6 clearly lists and tests a TPS as a primary ECU input. The Haynes Mitsubishi Pajero/Montero manual (1983–1995) also details TPS adjustment and diagnosis for EFI variants of this era. By contrast, the Mitsubishi 4D56 diesel workshop manual covers a fully mechanical injection pump with no TPS, and carburetted petrol models (such as the 2.6‑litre 4G54) are likewise documented without a TPS. So, TPS relevance hinges on spec: EFI petrol Pajeros in 1988 have a TPS, carburetted petrol and mechanical‑diesel versions do not.

When a TPS isn’t used on a 1988 Pajero, it’s because the engine management doesn’t need throttle angle data. Carburettors meter fuel mechanically via vacuum and jets, and the 4D56’s mechanical pump meters diesel by governor and boost compensation, so there’s no ECU demanding a TPS signal.

For EFI‑equipped 1988 Pajeros that do run a TPS, the sensor tells the ECI‑Multi ECU exactly how far the throttle is open, so it can trim fuelling and ignition timing from closed‑throttle idle through to wide‑open throttle. That helps with smooth take‑off, crisp mid‑range response, and better economy on cruise. Over time, heat, vibration and wear can cause dead spots or drift in the sensor, leading to rough idle, hesitation off the mark, erratic revs, or a fuelly smell. Some will even log a fault code on the ECI‑Multi system.

As part of regular servicing, it’s worth giving the throttle body a clean and checking TPS operation with a multimeter. While exact specs vary by engine and market, many Mitsubishi EFI systems expect roughly 0.5 V at closed throttle and around 4.5 V at wide‑open, with a smooth, linear sweep in between. Any jumps or flat spots mean the TPS is on the way out. If adjustment is provided, the sensor can be rotated slightly to set base voltage—always follow the factory procedure in the FSM and recheck base idle once done.

Replacement is straightforward: disconnect the plug, remove the two retaining screws, transfer the new unit, and set alignment marks before tightening. Don’t over‑torque the screws into the throttle body. After refit, confirm voltage and throttle‑closed switch (if fitted) operation. Practical tips owners appreciate:

• Back‑probe the connector with the key on, engine off, for safer voltage checks.
• Inspect the loom for brittle insulation or green corrosion at the plug.
• If idle still hunts after a TPS swap, revisit base idle and air leaks.

There’s no fixed replacement interval, in Aussie and Kiwi conditions, a check every 40,000–50,000 km during a major service keeps things sweet and avoids chasing your tail on drivability gremlins.

FAQs

Does a 1988 Pajero actually have a TPS?
It depends on the engine. EFI petrol models (notably the 3.0‑litre 6G72 with ECI‑Multi) do, and the factory service manual lists test steps and specs. Carburetted petrol versions and the 4D56 mechanical‑diesel don’t have or need a TPS. Checking the intake—throttle body with injector rails and an ECU loom usually means EFI and a TPS.

What are the signs a TPS is failing on an EFI 1988 Pajero?
Common symptoms include a stumble off idle, flat spots under light throttle, surging cruise, rough idle, and higher fuel use. Some ECUs will store a fault code. A smooth voltage sweep test from closed to wide‑open throttle will quickly confirm if it’s healthy.

Can a TPS be cleaned, or should it just be replaced?
Unlike a throttle body, the TPS is a sealed sensor. Cleaning the throttle plate helps airflow, but a worn or erratic TPS is best replaced. After fitting, set the base position/voltage per the FSM and recheck idle speed and timing so the ECU knows exactly where “closed” is.