Parts for your 1998 Mitsubishi Pajero-Egr valve

1998 Mitsubishi Pajero EGR Valve: What it does and how to look after it

Based on Mitsubishi factory documentation — Pajero/Montero 1997–1999 Workshop Manual (Group 13A: Engine Emission Control), the Mitsubishi 4M40 Engine Service Manual, and Gregory’s/Glen’s repair manuals for 1991–1999 models — the 1998 Mitsubishi Pajero is fitted with an Exhaust Gas Recirculation (EGR) valve on both the 2.8‑litre 4M40 turbo‑diesel and the 3.0/3.5‑litre 6G7 petrol variants. These systems support Australian and New Zealand emissions compliance for the era (e.g., ADR 37/01 for petrol and ADR 70/00 for diesel).

For anyone running a ’98 Pajero, the EGR valve is there to cut nitrogen oxides (NOx) by feeding a measured amount of exhaust back into the intake. That drops combustion temps, smooths diesel combustion a touch, and helps keep the rig cleaner at part‑throttle. On the 4M40 diesel, it’s vacuum‑controlled with a modulator and solenoid, on the V6 petrol engines, operation is similar in principle, with the valve mounted on or near the intake manifold.

Like any 90s EGR setup, carbon can cake up the valve and passages. When that happens, drivers may notice a rough idle, flat spots off the line, pinging on petrol, a bit of extra smoke on diesel, higher fuel use, or a fault for EGR flow. Keeping it happy is mostly about periodic inspection and cleaning rather than constant parts swaps.

Good workshop practice for servicing includes:

• Inspect and clean the valve and intake passages every 40,000–60,000 km on diesels, petrols can stretch further if driving is mostly open road.
• Check vacuum hoses and the EGR solenoid/modulator for splits or lazy operation.
• Bench‑test the valve with a hand vacuum pump — the diaphragm should hold vacuum and the pintle should move smoothly.
• Clean with EGR/throttle‑body safe cleaner. Don’t flood the diaphragm, keep solvents off rubber parts.
• Refit with a new gasket, ensure hoses are routed correctly, clear any stored EGR faults, and road‑test.

If the diaphragm leaks or the shaft is seized, replacement is the go — choose quality OEM or reputable aftermarket. Diesel owners can reduce soot build‑up by using good fuel, sticking to low‑ash oil that meets spec, and letting the engine stretch its legs on a decent run now and then. And a quick word on legality: blanking or deleting the EGR might be common chat in forums, but it’s not road‑legal in Australia or New Zealand and can cause compliance headaches.

Popular questions

Does a 1998 Mitsubishi Pajero actually have an EGR valve?
Yes. Factory documentation covers EGR on both the 2.8‑litre 4M40 turbo‑diesel and the 3.0/3.5‑litre 6G7 petrol engines for this model year. It’s a standard emissions component designed to control NOx and keep the vehicle compliant for AU/NZ markets.

Can the EGR valve be cleaned instead of replaced?
Often, yes. If the diaphragm holds vacuum and the pintle moves freely, a thorough clean of the valve and intake passages usually restores proper flow. Replace the gasket on reassembly and check all vacuum lines. If the diaphragm is torn or the valve is jammed solid, replacement is the sensible fix.

Is EGR blanking legal on a 1998 Pajero in Australia or NZ?
No. EGR removal or blanking breaches emissions rules and can trigger inspection, WOF/RWC, and insurance issues. It can also increase NOx, which isn’t great for air quality. Better to service the system so it works as intended.