1991–1995 Mitsubishi Sigma and Diamante Service Manual (P/N PWGE9004-G)

• Covers European-market Mitsubishi Sigma F16A 4-door sedans in the F16AS...6 model-code family, including left- and right-hand-drive versions with 6G72 SOHC or DOHC V6 engines.
• The chassis decoder lists model-year codes M, N, P, and S—1991, 1992, 1993, and 1995—with build notes through April 1994 and an engine serial-number change from June 1993.
• Matches the F5M33-5 5-speed manual and electronically controlled F4A33-ELC 4-speed automatic transmission.
• Mitsubishi Motors publication Pub. No. PWGE9004-G, based on the November 1990 base issue and revised through May 1994. The digital set contains 29 PDF files totaling 1,441 pages.

Component and Systems Documentation

The vehicle-identification material decodes the information plate, F16AS model code, engine and transmission codes, trim level, steering position, European destination code, chassis-number location, and engine-number stamping. Coverage is tied to the European Sigma F16A codes rather than a blanket Diamante application, so the vehicle code plate provides the clearest fitment check before purchase.

This technical manual follows the scope of Mitsubishi's chassis workshop publication. For the engine and transmissions, it covers on-vehicle inspection and adjustment plus removal and installation of major assemblies. Internal bench inspection, teardown, and rebuild after removal belong to the separate 6G72, F5M33, and F4A33 publications identified in the foreword. Full vehicle wiring diagrams are covered in separate left- and right-hand-drive Electrical Wiring manuals, although system-level circuit diagrams, connector checks, and diagnostic charts are included here.

The fuel section covers multi-point injection (MPI), self-diagnosis, engine-warning-lamp codes, harness checks, throttle-position and idle-switch adjustment, injector and fuel-pump tests, TCL checks, and auto-cruise control diagnosis. Active-ECS material adds service data, actuator tests, vehicle-height adjustment, rolling diaphragms, reserve tanks, the compressor, solenoid valve/dryer, air tubes, height sensors, and G-sensor checks. Separate groups address ABS and TCL troubleshooting, the brake hydraulic unit and wheel-speed sensors, hydraulic 4WS with its rear oil pump and power cylinder, power steering with E.P.S. solenoid/control-unit checks, axles, suspension, body and glass, lighting, SRS, and air conditioning for both R-12 and R-134a systems.

Named visual references include the Multi Point Injection System Diagram, Vacuum Hose Piping Diagram, F4A33 Automatic Transmission Sectional View, E.L.C. 4-Speed Automatic Transmission Control Components Layout, SRS Construction Diagram, and Sunroof Circuit Diagram. Component illustrations and exploded views identify non-reusable parts, lubrication and sealant points, service sequence, and torque values in Nm, kgm, and ft-lb.

Engine, Transmission, and Torque Reference Data

Both 6G72 versions are identified as 2,972 cc V6 engines with a 91.1 x 76 mm bore and stroke, 10.0:1 compression ratio, 1-2-3-4-5-6 firing order, and hydraulic lash adjusters. Service data distinguishes SOHC and DOHC limits: idle speed is 700 ± 100 rpm, minimum compression is 1,050 kPa (149 psi) for SOHC and 980 kPa (139 psi) for DOHC, and the maximum cylinder-to-cylinder difference is 100 kPa (14 psi). DOHC ignition-timing tolerances are separated for vehicles built through November 1992 and those built from December 1992.

Named repair procedures include drive-belt tension, ignition timing, idle speed and mixture, compression and manifold-vacuum testing, lash-adjuster inspection, SOHC/DOHC timing-belt work, oil-pan service, camshaft and crankshaft seal replacement, cylinder-head-gasket service, and engine-assembly removal and installation. The special-tool tables identify MD998051 for cylinder-head bolts, MD998717 and MD998718 for front and rear crankshaft oil seals, and MD998754 for supporting the DOHC crankshaft pulley. Diagnostic equipment coverage includes the MB991341 Multi-use tester and MB991502 MUT-II, with ROM pack MB991419 for vehicles built through May 1992 and MB991481 from June 1992.

For the F4A33 automatic, the publication includes the hydraulic circuit, electronic control layout, fault-code readout, shift-pattern checks, converter stall testing, oil-pressure and actuator tests, kickdown-servo adjustment, line- and reducing-pressure adjustment, and inhibitor-switch/control-cable setup. Standard line pressure is 870-890 kPa (124-126 psi), and the specified fill is 7.5 L (7.9 US qt) of DIA QUEEN ATF-SP or equivalent. The F5M33 section covers oil-level and oil-change data, shift controls, the lever assembly, and transmission-assembly removal and installation.

Several cautions are specific to these repair jobs. During DOHC timing-belt work, turning a camshaft sprocket with No. 1 cylinder at TDC can produce valve-to-piston contact; rotating one front-bank sprocket a full turn while the opposite timing marks are aligned can also cause valve interference. On DOHC engines built from November 1992, using oil-pan remover MD998723 can damage the aluminum upper oil pan. SRS circuits are restricted to specified test equipment—an analog ohmmeter can create an accidental deployment risk or leave the system inoperative.

The SRS section also warns that deployment voltage remains after battery disconnection. ABS hydraulic, Active-ECS, fuel, and refrigerant repair work should follow the listed isolation, pressure-release, and refrigerant-handling precautions. For independent repair shops, technicians, and experienced owners, the practical value is the configuration-specific test data and procedure scope needed to select the correct repair path before parts are removed.