Suzuki Grand Vitara JB416 / JB420. Manual — part 100

1D-68 Engine Mechanical: For J20 Engine

Air Cleaner Element Introduction

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This air cleaner element is dry type. Remember that it needs cleaning according to “Air Cleaner Filter Inspection and
Cleaning: For J20 Engine”.

IMT (Intake Manifold Tuning) System Description

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IMT (Intake manifold tuning) system consists of the following items:
• IMT valve (5) fixed on intake manifold (1)
• IMT valve actuator (4)
• IMT vacuum solenoid valve (2)
• Vacuum tank (3)

1

2

3

4

5

6

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Engine Mechanical: For J20 Engine 1D-69

Vacuum tank contains the one way check valve (6) to maintain negative pressure constantly regardless of variation in
the intake manifold pressure.
Vacuum tank, therefore, supplies IMT vacuum solenoid valve actuator with stable negative pressure in whole engine
speed ranges.

IMT (Intake manifold tuning) system varies effective length of intake pipe by opening and closing IMT valve in order to
improve air volumetric efficiency.
As intake valve in cylinder head is opened and closed repeatedly, intake air pulsation always exists. If intake valve is
opened when air pressure is momentarily maximum, intake air volumetric efficiency is increased. This momentary
maximum air pressure depends on effective intake pipe length.

When IMT valve is fully open [A]:
The effective intake pipe length is shorter. Engine torque between middle and high engine speed ranges is improved,
whilst it drops between low and middle engine speed ranges.

When IMT valve is totally closed [B]:
The effective intake pipe length is longer. Engine torque between middle and high engine speed ranges drops, while it
is improved between low and middle ranges.

IMT system utilizes this characteristic of engine. IMT valve is closed between low and middle engine speed ranges,
and opened between middle and high engine speed ranges.
In this way, engine torque is improved in whole engine speed ranges.

[B]

[A]:

[A]

[B]:

[A + B]

3

3

4

4

min

-1

(rpm)

min

-1

(rpm)

2

1

2

1

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[A]: IMT valve open

1. IMT valve

3. Engine torque

[B]: IMT valve closed

2. Intake manifold

4. Engine speed

1D-70 Engine Mechanical: For J20 Engine

System Operation
IMT vacuum solenoid valve open:
When IMT vacuum solenoid valve is OFF, the actuator side of IMT vacuum solenoid valve is lead to relief port. Under
this condition, the negative pressure is not applied to IMT valve actuator. The IMT valve, therefore, is totally opened
due to the force of return spring in IMT valve actuator.
The effective intake pipe length, therefore, becomes shorter.
IMT valve closed:
When IMT vacuum solenoid valve is ON, the actuator side of IMT vacuum solenoid valve is lead to vacuum tank.
Under this condition, the negative pressure of vacuum tank is applied to IMT valve actuator. The IMT valve, therefore,
is totally closed because the return spring in IMT valve actuator is compressed due to the negative pressure.
The effective intake pipe length, therefore, becomes longer.

Diagnostic Information and Procedures

Compression Check

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Check compression pressure on all 4 cylinders as
follows:

1) Warm up engine.
2) Stop engine after warming up.

NOTE
After warming up engine, place transmission
gear shift lever in “Neutral” (shift selector
lever to “P” range for A/T model), and set
parking brake and block drive wheels.

3) Remove engine cover.
4) Disconnect ignition coil couplers.
5) Disconnect ignition coils (1).
6) Remove all spark plugs (2).

7) Disconnect fuel injector wire harness at the coupler.
8) Install special tool (Compression gauge) into spark

plug hole.

Special tool
(A): 09915–64512
(B): 09915–64530
(C): 09915–67010

9) Disengage clutch (to lighten starting load on engine)

for M/T vehicle, and depress accelerator pedal all
the way to make throttle fully open.

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Engine Mechanical: For J20 Engine 1D-71

10) Crank engine with fully charged battery, and read the

highest pressure on compression gauge.

NOTE

• For measuring compression pressure,

crank engine at least 250 rpm by using
fully charged battery.

• If measuring compression pressure is

lower than limit value, check installation
condition of special tool. If it is properly.

Compression pressure
Standard: 1400 kPa (14.0 kg/cm

2

, 199.0 psi)

Limit: 1100 kPa (11.0 kg/cm

2

, 158.0 psi)

Max. difference between any two cylinders: 100
kPa (1.0 kg/cm

2

, 14.2 psi)

11) Carry out Steps 8) through 10) on each cylinder to

obtain 4 readings.

12) After checking, install spark plugs (2) and ignition

coils (1).

13) Install ignition coil couplers.
14) Connect injector wire harness at coupler.
15) Install engine cover.

Engine Vacuum Check

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The engine vacuum that develops in the intake line is a
good indicator of the condition of the engine. The
vacuum checking procedure is as follows:

1) Warm up engine to normal operating temperature

and make sure that engine idle speed is within
specification.

NOTE
After warming up engine, place transmission
gear shift lever in “Neutral” (shift selector
lever to “P” range for A/T model), and set
parking brake and block drive wheels.

2) Stop engine and remove engine cover.
3) Disconnect vacuum hose (1) from vacuum pipe.
4) Connect special tools (vacuum gauge and hose

joint) to vacuum hose of intake manifold side.

Special tool
(A): 09915–67311
(B): 09918–08210
(C): 09355–35754–600 Hose, SUZUKI GENUINE
PARTS
(D): 09367–04002 3-way joint, SUZUKI GENUINE
PARTS

5) Start engine and run engine at specified idle speed,

and read vacuum gauge. Vacuum should be within
specification.

Vacuum specification
52.6 – 65.8 kPa (40 – 50 cmHg, 15.7 – 19.7 in.Hg)
at specified idle speed

6) After checking, remove special tools.
7) Connect vacuum hose to vacuum pipe.
8) Install engine cover.

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1

(C)

(D)

(B)

(A)

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