Parts for your 1991 Mitsubishi Pajero-Map sensor

1991 Mitsubishi Pajero MAP sensor — do they have one?

Short answer: a 1991 Mitsubishi Pajero generally doesn’t use a MAP (manifold absolute pressure) sensor for engine management. Technical references that back this up include the Mitsubishi Factory Service Manual for the 1991 Pajero/Montero (Group 13A Multiport Fuel Injection and Group 13B Diesel), the Mitsubishi ASA/CAPS parts catalogue for V31/V32/V33 series, and the Haynes Mitsubishi Pajero/Montero 1983–1996 manual. These sources show the 3.0L V6 (6G72) petrol models run a Kármán‑vortex mass air flow (MAF/airflow meter) system, and the 2.5L 4D56T diesel models use a fully mechanical rotary injection pump—neither setup relies on an external, replaceable MAP sensor. Autodata engine management guides of the period tell the same story for the 6G72 Pajero: MAF-based fueling, no standalone MAP.

Why no MAP? The 6G72 petrol is calibrated as a MAF system from the factory. The ECU meters incoming air with the airflow sensor in the intake duct, then trims with the O₂ sensor, coolant temp sensor, and throttle position—so it doesn’t need a manifold pressure input. On the 4D56T diesel, fuelling is governed mechanically, boost enrichment comes via an aneroid (boost compensator) on the pump that’s fed manifold pressure by a hose. That device isn’t an electronic sensor, so there’s no MAP to diagnose or replace.

Owners sometimes spot a small box with a vacuum hose and assume it’s a MAP. On a 1991 Pajero that’s more likely a vacuum switching solenoid, a dash boost-gauge sender on some markets, or simply the hose to the diesel pump’s aneroid. Later models (e.g., some 1993–on variants like the 4M40 2.8TD) did gain a pressure/boost sensor for EGR or overboost control, but that’s not the typical 1991 setup.

Handy checks to confirm what’s fitted on a specific vehicle:

• Petrol 3.0 V6: look for the airflow meter in the intake snorkel/airbox. The factory manuals and ASA/CAPS list an air flow sensor, not a MAP.
• Diesel 2.5: look for the boost line running to the injection pump’s aneroid, there’s no engine ECU MAP to service.
• Scan the ECU or review the fault code list, MAP-related codes aren’t present on the 1991 petrol ECU pinout or code tables in the factory manual.

So if they’re chasing idle or fueling woes on a ‘91 Paj, they won’t be buying a MAP sensor. Petrol owners should check the MAF, vacuum leaks, and base idle settings, diesel owners should inspect boost hoses, the aneroid line, and general pump health.

FAQs

Does a 1991 Pajero have a MAP sensor?
Most 1991 Pajeros do not. The 3.0 V6 runs a MAF (airflow meter) system, and the 2.5 diesel is mechanically injected. Factory service information and parts catalogues list no external MAP sensor for these models.

What’s the “sensor” on my diesel with a vacuum/boost hose?
That’s typically the aneroid (boost compensator) on the injection pump, or a related hose/valve. It reacts to boost pressure mechanically to add fuel—it’s not an electronic MAP sensor.

Can a MAP sensor be added with an aftermarket ECU?
Yes. If converting to a speed‑density setup, a MAP sensor can be installed and tuned accordingly. That’s a custom modification and not part of the factory 1991 arrangement.