Engine Mitsubishi 4a31
Content
Petrol four-cylinder in-line 16-valve engine, 1,1 l (1094 cc). Mitsubishi 4A31 is produced from 1999 to the present.
Developed on the basis of the predecessor 4A30 with a volume of 660 cubic meters. cm, equipped in the first version with a carburetor, and in a later version with an injection fuel supply system.
The Mitsubishi 4A31 engine is available in two versions. On one version of the internal combustion engine, the usual ECI multi-point fuel injection system was implemented, on the other, the GDI system (allowing the engine to use the lean mixture most efficiently). The latter increased the efficiency of the vehicles on which it was installed by almost 15%.
Comparative characteristics of two modifications:
History of creation
Mitsubishi Motors needed a more powerful than 4A30, and at the same time economical engine in order to occupy a "niche" between the popular key-car Minica (mini cars with engines up to 700 cc), and power units with a volume of 1,3-1,5 .XNUMX l. The company's designers decided to refine the first in the line of four-cylinder engines, equipping it with a GDI system.
The predecessor of the "thirty-first" - the 4A30 engine was put on stream in 1993. It was installed in a small city car Mitsubishi Minica, which showed an consumption rate of 1:30 (30 km per liter of fuel). The percentage indicator of high efficiency was successfully fixed, while increasing the volume and power of the motor, and leaving the previous layout of the unit.
Design changes affected the volume of the cylinder, the diameter of the cylinder (from 60 to 6,6), the location of the valves and injectors. The compression ratio has been increased from 9:1 to 9,5:1 and 11,0:1.
Features
The estimated service life of the 4A31 power unit before overhaul is approximately 300 km of car run. The motor is equipped with 000 valves per cylinder, driven by one common overhead camshaft. The cylinder block is made of cast iron. The coolant pump housing and cylinder head are made of aluminum alloy. The motor is liquid cooled.
Characteristics of KSHG, CPG:
- Cylinder sequence: 1–3–2–4.
- Valve material: steel.
- Piston material: aluminium.
- Piston seat: floating.
- Ring material: cast iron.
- Number of rings: 3 (2 workers, 1 oil scraper).
- Crankshaft: forged 5 bearing.
- Camshaft: cast 5 bearing.
- Timing drive: toothed belt.
The nominal value of the clearance in the valve drive:
| On a warm engine | |
| Inlet valves | 0,25 mm |
| Exhaust valves | 0,30 mm |
| On a cold engine | |
| Inlet valves | 0,14 mm |
| Exhaust valves | 0,20 mm |
| Torque | 9 +- 11 N m |
The volume of engine oil in the 4A31 engine is 3,5 liters. Of these: in the oil sump - 3,3 liters; in the filter 0,2 l. Original Mitsubishi oil 10W30 (SAE) and SJ (API). It is allowed to fill in a motor with high mileage with analogues with a viscosity index of 173 (Texaco, Castrol, ZIC, etc.). The use of synthetic oils prevents the rapid "aging" of the material of the valve stem seals. The consumption of lubricating fluid allowed by the manufacturer is not more than 1 liter per 1000 km.
Advantages
The Mitsubishi 4A31 motor is a reliable and durable power unit with high maintainability. Subject to the maintenance intervals, timely replacement of the drive belt and timing belt, the use of high-quality lubricants and fuel, its practical resource (according to reviews) will be 280 km or more.
Weak spots
Judging by the reviews of the owners, there is a specific problem characteristic of the "elderly" Pajero Junior - increased fuel consumption. The exhaust manifold cracks from vibrations and the oxygen sensor sets the wrong parameters for the fuel management system.
Typical faults:
- Tendency to increased oil consumption after the 100 km mark. The loss often reaches 000-2000 ml per 3000 km.
- Frequent failure of the lambda probe.
- The tendency for piston rings to lie (depends on the quality of the fuel and the preferred operating modes - high or low speed).
The 4A31 timing belt resource declared by the manufacturer before replacement is from 120 to 150 thousand km (experts recommend regularly monitoring its condition, starting from a run of 80 km, and changing it if significant abrasions appear). Replacing the timing belt is recommended when replacing a faulty Mitsubishi 000A4 engine with a contract engine, regardless of its mileage.
Details of the timing mechanism 4A31
Scheme for checking the coincidence of the timing mark
The location of the timing marks on the oil pump housing
The location of the timing marks on the camshaft gear
The timing of the recommended replacement of the timing belt is indicated on the sticker on the top of the mechanism casing.
Vehicles fitted with the Mitsubishi 4a31 engine
All cars on which the Mitsubishi 4A31 engine was installed were built on the basis of the 6th generation of the Mitsubishi Minica (E22A) model of 1989. The car was equipped with a 40-horsepower 0,7-liter engine. The successors of the Mitsubishi Minik are right-hand drive, originally aimed at the Japanese market.
Mitsubishi Pajero Junior
Mitsubishi Pajero Junior (H57A) 1995-1998 Popular all-wheel drive SUV - the third after the Mini in the Pajero family. It was produced in two trim levels: the ZR-1 is more budgetary, and the ZR-2 is equipped with a central lock, power steering and decorative wood trim. Completed 3-st. Automatic transmission, 5-st. manual transmission. The manual transmission version has become the most popular among off-road enthusiasts.
Mitsubishi Pistachio
Mitsubishi Pistachio (H44A) 1999 The name translates as "pistachio". Economical front-wheel drive three-door hatchback. Structural changes affected the body in the front - to fit it to the fifth size group, as well as the transmission - equipment 5-speed. manual transmission. The experimental model, released in only 50 copies, did not enter the retail network, but entered the service of government agencies.
Mitsubishi Town Box Wide
Mitsubishi TB Wide (U56W, U66W) 1999–2011 Five-door all-wheel drive minivan with 4-speed. Automatic transmission or 5-st. Manual transmission for the Japanese domestic market. In 2007, it was sold under the Nissan brand (Clipper Rio). Also produced under license in Malaysia under the brand name Proton Juara.
Mitsubishi Toppo BJ Wide
Front wheel drive or full time 4WD, minivan with 4 tbsp. automatic transmission. Modification of the Mitsubishi Toppo BJ, which differs from it, except for the engine, by an increased number of seats in the cabin (5) and a complete set.
engine change
Mitsubishi 4А31 is used as a SWAP-donor for installation in Mitsubishi Pajero Mini, instead of its obsolete 660-cc unit. Replacement is carried out together with the exhaust manifold, wiring and electronic control unit. The six-digit (2 letters and 4 digits) engine number is printed on the plane of the crankcase 10 cm below the exhaust manifold.
