Parts for your 1998 Mitsubishi Pajero-Fuel injectors

1998 Mitsubishi Pajero fuel injectors — what they do and how to look after them

Based on technical references including the Mitsubishi Pajero (V20 series) Factory Service Manual (1997–1999), Autodata/Autoinfo service data, and Gregory’s/Haynes repair manuals, the 1998 Mitsubishi Pajero is fitted with fuel injectors. Petrol variants run multi‑point fuel injection (MPI) or, in some markets, GDI direct injection, while the 2.8L 4M40 turbo‑diesel uses mechanically or electronically controlled diesel injectors. So fuel injectors are definitely relevant on this model.

On a 1998 Pajero, the injectors’ job is to meter and atomise fuel so the engine burns cleanly and efficiently. In the petrol 6G72/6G74 engines, the ECU commands each injector to deliver precise pulses for smooth idle, decent power, and tidy fuel economy. On the 4M40 diesel, the pump builds high pressure and the injectors pop at a set opening pressure to produce a fine spray pattern, which is critical for cold starts, torque, and keeping smoke down.

Keeping injectors happy pays off. Petrol injectors can gradually gum up from varnish, leading to rough idle, flat spots, and higher fuel use. Professional on‑car cleaning or ultrasonic bench cleaning can restore flow balance if spray patterns are still good. If electrical coils go open‑circuit or the pintle is worn, replacement is the fix. Expect longer life if quality fuel is used and the fuel filter is changed on time.

Diesel owners should treat injector servicing as routine. On the 4M40, plan pop‑testing and spray‑pattern checks about every 100,000–120,000 km, or sooner if there’s hard starting, knock, haze, or poor economy. Nozzles and sealing washers are wear items, renewing them and resetting opening pressure brings the engine back to its best. Always replace the copper washers and leak‑off hoses when refitting.

• Replace the fuel filter at 20,000–40,000 km intervals (check the service schedule). Keep the diesel water separator drained.
• For petrol MPI, relieve fuel pressure before removal. For GDI or diesel, observe high‑pressure safety—don’t crack lines with the engine running.
• Use new O‑rings and rail seals, torque to spec, then prime the system, check for leaks, and clear any ECU fault codes.
• If the intake plenum must come off (common on V6s), budget for new gaskets and a throttle body clean while it’s apart.

Done right, refreshed injectors restore smooth running, easier starts, and better economy—handy for long Kiwi and Aussie kilometres.

What are common symptoms of worn injectors on a 1998 Pajero?

Owners often notice rough idle, hesitation under load, increased fuel use, diesel knock or haze, and hard starting. Petrol engines may also show misfire codes. Diesel 4M40s can feel down on torque and produce more smoke when nozzles are coked or opening pressures drift.

A proper diagnosis includes balance testing, leak‑down checks, scan data (petrol), and pop‑testing (diesel). Ruling out air leaks and weak lift pumps is smart before blaming the injectors.

How often should diesel injectors be serviced on the 4M40?

As a rule of thumb, every 100,000–120,000 km is sensible, or sooner if symptoms appear. Service typically includes removing the injectors, pop‑testing, cleaning or replacing nozzles, fitting new sealing washers, and setting opening pressure to spec.

Pair this with timely fuel filter changes and water separator maintenance to extend injector life.

Can petrol injectors be cleaned or do they need replacing?

Light to moderate deposits usually respond well to professional cleaning, especially ultrasonic off‑car cleaning with flow testing. If an injector has electrical failure, cracked body, or poor spray even after cleaning, replacement is the way to go.

When replacing, stick with quality units and new O‑rings, and recheck for leaks after the first short drive.