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Part I Engine

Chapter 1 Engine Assembly

(MR479Q, MR479QA, MR481QA)

Section 1 Routine Inspection

1. Check coolant

2. Check engine oil

3. Check battery

4. Check air cleaner element assembly

5. Check spark plug

6. Check drive belt

Figure 1

Notice:

z

Check the belt deflection at the specified point  See (Figure 1).

z

Set tension to specified value when installing new belt.

z

Check the deflection to ensure it is below the specified value after the belt runs for over 5 minutes.

z

Reinstall the belt which has been running for over 5 minutes. The deflection of the old belt is regarded as

the standard for inspection.

z

Check V-belt for tension and distortion after the engine cranks for 2

turns.

7. Check ignition timing See (Figure 2)

a) Warm up the engine.

b) When using fault diagnosis tester

 Connect fault diagnosis tester to fault diagnosis interface socket.

Ignition timing:

MR479Q:  10 ± 2° BTDC (before top dead center) at idle

MR479QA: 10 ± 2° BTDC at idle

MR481QA: 10 ± 2° BTDC at idle

Figure 2

New Belt mm

Old Belt mm

Fan Belt                     7

～

13.5

Power steering Belt            5

～

6

6

～

8

A/C Belt                    6. 5

～

7

8

～

9

Belt deflection See (Table 1) 

Belt pressure: 98N

Belt Looseness Measuring Point

Water pump

Power steering

crankshaft

generator

Air condition

 compressor

pump

11.5

～

9

2

c) When fault diagnosis tester is not used

(1)  Shorting fault diagnosis interface socket 13 (TC) terminal and 4(CG) terminal.

Notice:

z

Ensure correct connection, otherwise the engine will be damaged.

z

Switch off all electrical appliance system.

z

Check when disconnecting cooling fan motor.

(2) Using timing light to check ignition timing.

Ignition timing: 10 ± 2° BTDC at idle

Notice:

(1) Transmission shift lever should be in neutral position when checking ignition timing.

(2)  Running engine at 1,000-1,300rpm for 5s and check at idle.

(3)  Remove the tester on fault diagnosis socket.

(4)  Ignition timing advance angle becomes larger when the engine roate speed is higher.

(5) Remove timing light.

8. Check engine idle See (Figure 3)

Notice:

z

Check idle when cooling fan motor is disconnected.

z

Switch off all electrical accessories and A/C.

9. Check compression pressure See (Figure 4)

(a) Engine switched off.

(b)  Detach high voltage cable.

(c)  Detach spark plug.

(d) Check the compression pressure in the cylinder.

(1)

Insert pressure gauge into the hole of the spark plug.

(2)

Throttle valve full open.

(3)

Crank the engine, measure the compression pressure.

     MR479Q

800±50 (rpm)

     MR479QA

800±50 (rpm)

    

 

MR481QA

800±50 (rpm)

Table 2

(a) Warm up the engine.

(b)  Connect fault diagnosis tester to fault diagnosis interface socket.

(c) Connect tachometer testing pen to fault diagnosis socket terminal 

9 when not using fault tester.

(d) Check idle See (Table 2).

Figure 4

Figure 3

Techometer

Battery

3

The Min. compression pressure:  980 kPa

The tolerance range of the cylinders pressure: 100 kPa

Notice:

z

Ensure sufficient battery power and the engine speed is no less than 250 RPM (revolutions per minute).

z

Check the compression pressure of other cylinders in the same way.

z

Complete the measure as quick as possible.

(4)  If the compression pressure in several cylinder is too low, fill some engine oil to the cylinder via the

hole of the spark plug. Check by repeating step 1-3.

Hint:

z

If the compression pressure is improved after filling oil, the piston ring or the cylinder may be abrased

or  damaged.

z

If the pressure is still too low, the valve is stagnation or poor seal, or there is a leakage in gasket.

10. Check CO/HC

(a)  Start engine.

(b) Running engine at 2500rpm for approximately 3 minutes.

(c) Insert CO/HC meter testing probe into tailpipe at least 40cm during idling.

(d) Check CO/HC concentration at idle and 2500rpm.

Hint:

z

Complete measurement within 3 minutes.

z

Test the CO/HC emission concentration at idle and 2500 rpm on QC/T630-1999 standard.

(e) Take the following steps to diagnose the fault if the CO/HC concentration does not comply with standard .

(1) Check the oxygen sensor operation.

(2) See (Table 3) for the possible cause and check and repair.

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Table 3

   CO

  HC

Problems

Causes

1. Fault

. Incorrect ignition timing

. Fouled, shorted or improperly clearance of spark plug

2. Incorrect valve clearance 

3. Leaky intake & exhaust valves

4. Leaky cylinders

1. Air leaks

. PCV hoses, intake manifold 

. Throttle body

. Brake booster circuit

2. Lean mixture gas causing misfire

1. Clogged air filter

2. Clogged PCV valve

. Faulty ECU

. Faulty fuel pressure regulator

. Faulty water temperature sensor

. Faulty air compressor

. Faulty injectors

. Faulty throttle position sensor

Normal

Low

High

High

High

Rough idle

(Black smoke

from exhaust

pipe)

Rough idle

Rough idle

High