Bosch 221-122-001 Coil Resistance

1 - Battery

2 - Ignition switch

3 - Ignition control unit

4 - Ballast resistor

5 - Distributor

6 - Ignition coil

7 - To starter termi nal 16

8 - To tachometer

ADJUSTING IGNITION TIMING

1. Run engine to operating temperature (oil temperature about 80 to 90° C/176 to 194° F).

Unlike capacitor discharge ignition systems, testing equipment (e.g. tachometer) can be connected to ignition coil terminals 1 and 15 of transistorized ignition coil systems.

2. Connect engine tester or timing light and tachometer. A positive terminal for connection of testing equipment is located above ignition control unit in engine compartment.

3. Detach both vacuum hoses at distributor.

4, Adjust ignition timing to 31° before TDC at engine speed of 3000 rpm. Loosen and turn distributor to change ignition timing.

Bosch Magneto Mjk Timing

5. Run engine at 5000 rpm, at which speed ignition timing must not exceed 36 .

Timing light is connected to ignition cable of cylinder number 1,

4, Adjust ignition timing to 31° before TDC at engine speed of 3000 rpm. Loosen and turn distributor to change ignition timing.

5. Run engine at 5000 rpm, at which speed ignition timing must not exceed 36 .

6. Attach vacuum hoses. Ignition timing must be 0-4° when engine runs at idle speed 800 - 50 rpmj.

Remove distributor and check it in a distributor test bench, if specifications in points 5 and 6 cannot be held.

Note

1. Ignition must be off when connecting tester to ignition coil.

2. The dwell angle is not adjustable and does not need to be checked.

CENTRIFUGAL ADVANCE CURVE FOR DISTRIBUTOR

BTDC

BTDC

Bosch Coil Resistance

VACUUM RETARD CURVE FOR DISTRIBUTOR

BTDC.

BTDC.

Bosch Coil Resistance

REMOVING AND INSTALLING DISTRIBUTOR

930 Turbo Adjusting Ignition Timing

2, Remove distributor cap, rotor and dust cap. 5. Adjust ignition timing.

Detach vacuum hoses and wires.

3. Unscrew mounting bolt and remove distributor.

4 When installing the distributor rotor make sure that it faces the cylinder 1 mark on distributor housing.

REPLACING SPARK PLUGS

1. Detach both air intake hoses, 4. Loosen and pull out air cleaner lower section clamping bolt in intake branch. Loosen air cleaner lower section bolts and remove air cleaner lower section to the right.

1. Apply a light coat of Molykote HTP white paste to plug threads.

2, Tightening torque: 25 to 30 Nm (18 to 22 ft lb)

Printed in Germany - IV, 1980

Replacing Spark Plugs

28-9

Distributor Cap Cover

1. Remove distributor cap, rotor and dust cover. 4. When installing, engage hole of pull rod in pin Pull off hoses from vacuum unit. on stator of transmitter.

2. Unscrew screws.

3. Press up and remove vacuum unit.

This can be done more easily by turning stator against left stop and holding in this position.

3. Press up and remove vacuum unit.

Note

The soft iron teeth of the transmitter must not be bent, regardless of circumstances.

Bosch 237 122 Vacuum Advance

TROUBLESHOOTING ELECTRONIC IGNITION SYSTEM (BOSCH TRANSISTORIZED IGNITION SYSTEM)

Testing Prerequisites:

Battery fully charged, fuel in tank, engine or ambient temperature between 0 and + 40 C/ 32 and 104 F (temperature has considerable influence on test values).

Note especially information concerning dangers of electronic ignition systems (see page 28 - 3).

Starter turns, engine will not start or does not develop sufficient power.

1. Connect spark gap tester to ignition coil terminal 4 and set length at 12 mm. Start engine.

12 mm spark gap present?

no yes go to point 7

Bosch Fix 7665 Checking Ohm

2. Check distributor cap, distributor rotor, ignition cables and spark plugs.

Resistance of ignition line including plug: 2.5 k Ohms.

Checking Spark Plug Resistance

Resistance of distributor rotor: 5 k Ohms.

Spark at spark plug?

3. Check ignition timing. Timing correct;

yes no no repair secondary side adjust timing

4. Check fuel system.

Engine receiving sufficient fuel?

^ -repair fuel system

Troubleshooting Electronic Ignition System

Printed in Germany

Ignition Coil With Resistor For Engines

5. Check resistors and ignition coil.

Bosch Coil Wiring Diagram

0.4 ohm resistor: 0.35 ... 0.45 ohm 0.6 ohm resistor: 0.55 ... 0.65 ohm

Ignition coil primary (term. 1 and 15):

Ignition coil secondary (term. 1 and 4): 7 ... 12 k Ohms

Resistances value correct?

replace resistor or ignition coil yes

Voltmeter Volts

6, Measure voltage of ignition coil terminal 15 against ground.

Turn on ignition.

Relay Primary Coil Terminal Porsche 944

Voltage at term. 15: at least 3 V at battery voltage of at least 11 volts (measure at same time).

Voltage correct?

yes no

Check voltage drop at wires and connections on ignition switch, resistors, ignition coil and control unit, and eliminate voltage drop.

go to point 11,

7, Check starting voltage.

Disconnect line leading to starter term. 15a at 0.4 ohm resistor and connect voltmeter. Operate starter. Measured voltage must be same as battery voltage (measured at same time).

Starting voltage good?

no yes

Eliminate break in supply line or contact 15a in starter relay.

8. Measure sensor resistance including sensor line at disconnected ignition control unit plug between terminals 7 and 31 d.

Measured value between 485 and 700 ohms?

Pull off sensor lines from distributor and repeat test on sensor system.

Resistance between 485 and 700 ohms?

9. Check sensor coil with sensor line for ground, between terminal 7 and ground; and terminal 31 d and ground.

Infinite resistance?

Replace sensor line.

Replace distributor.

Pull off sensor line from distributor and repeat test on sensor system.

Infinite resistance?

Bosch Coil Terminal Positive

10. Check sensor system for mechanical damage. Visual inspection: gap between rotor and stator?

Replace sensor line.

Replace distributor.

Sensor system good?

yes go to point 5.

Replace distributor.

11. Check voltage at ignition control unit plug terminal 15 against ground. Voltage must be same as battery voltage.

Voltage Drop Battery Terminals

Voltage correct?

Check voltage drop in line from ignition switch to control unit, and eliminate voltage drop.

12. Check voltage at ignition coil terminal 1 against ground.

Voltage correct?

-Replace control unit.

13. Check dwell angle (short test on warm engine).

Dwell angle 25 ... 39° at 1500 - 50 rpm Dwell angle 33 ... 40° at 5000 - 50 rpm

Dwell angle correct?

yes no

Perform test steps 8, 9 and 10. Replace control unit when sensor system is good.

Engine must start and/or engine power must be adequate. If not, there is a mechanical defect.

14. Ignition failure:

Disconnect tachometer (12-pin plug on instrument cluster, right, or plug C on central fuse/relay panel.

Ignition failure eliminated?

Replace control unit.

yes t

Replace tachometer.

IGNITION COMPONENTS - 1980 Models

Ignition Coil

Type/Model

Version

Remarks

928

928 602 503 00 Bosch No. 0 221 122 001

With two ballast resistors 0. 4 ohm and 0. 6 ohm

Distributor

Type/Model

Version

Remarks

928

928 602 032 03 Bosch No. 0 237 405 010

Centrifugal and vacuum advance and retard control

Distributor rotor without rev. limiter.

Spark Plugs

Type/Model

•Version

Remarks

928

Bosch WR8DS Beru RS 35

0. 7 + 0, 1 mm (0. 028 + 0. 004 in.)

Control Unit

Type/Model

Version

Remarks

928

928 602 702 02 Bosch No. A 227 010 123

Transistor coil ignition

The vacuum control range of the distributor is changed from 140 - 240 mbar to 360 - 470 mbar beginning with 1981 models.

Part No. for distributor is 928, 602. 032. 04 (Bosch No, 0237 405 020).

Printed in Germany - VII, 1983

Ignition Components

IGNITION ADJUSTING AND TESTING VALUES

Type

928

M 28/13/14

Ignition timing

23° BTDC at

(without vacuum)

3000 rpm

Advance installed

yes

Retard installed

yes

Idle speed (rpm)

750 - 50

Centrifugal advance

8 to 10° BTDC

(without vacuum)

at idle speed

29 to 34° BTDC

at 6000 rpm

Vacuum

Vacuum hose of

advance

conn. 2 on conn.

(at idle speed)

1

degrees of

"advance"

8 to 12°

adjustment

Speed increase

turned back

below 1000 rpm

Vacuum

Vacuum hose

retard degrees

(connection 2)

of retard adjustment

connected

(at idle speed)

"retard "

4 to 8«

refer Porsche to

their publication

4592, 21(928

Service Information)

page 7 3, Ignition

timing specs, do not

agree!

Porsche 928 Ignition CablePorsche 928 Ignition Cable

1. Run engine to operating temperature (oil tem- 5. Adjust ignition timing to 23° before TDC a:

perature about 80 to 90° C/176 to 194° F). an engine speed of 3000 RPM,

Loosen and turn distributor to change ignition timing.

6. Attach vacuum hoses again.

2, Connect engine tester. A positive terminal for connection of testing equipment is located in engine compartment.

3. Connect timing light to ignition cable of cylinder 1.

4. Pull off both vacuum hoses at distributor.

CHECKING IGNITION TIMING - From 1980 Models

1, Check centrifugal advance (see table),

2, Check vacuum unit (see table)

Porsche 928 Vacume Hoses

1 - Advance

2 - Retard

Note

After completion of tests reconnect vacuum hoses.

Requirements:

Ignition timing adjustment is correct,

1, Check centrifugal advance (see table),

2, Check vacuum unit (see table)

Idle speed vacuum available at connection 2 can be used to check ignition advance.

This requires connecting the vacuum hose from retard unit to the advance unit.

Vacuum connections

1 - Advance

2 - Retard

Note

After completion of tests reconnect vacuum hoses.

If specified testing values can ' t be reached, remove distributor for inspection on a test bench.

CENTRIFUGAL ADVANCE CURVE TYPE 9 28 - from 19 80 Models

BTDC

-A-

t

3 XI

-a <

-

1

i

0 500 1000 1500 2000 2500 3000 3500 Distributor Shaft Speed (rpm) ,____^

0 500 1000 1500 2000 2500 3000 3500 Distributor Shaft Speed (rpm) ,____^

VACUUM ADVANCE CURVE TYPE 928 - from 19 80 Models

Bosch 237 122 Vacuum Advance

VACUUM ADVANCE CURVE TYPE 928 from 1981 Models BTDC

-4-

1

t

1

1

!

-

-

■ ■

-

-

1

!

i

- \ ' 1

]

-----

-

--

ATDC 100 200 300 400 500 600 Vacuum (mbar) -——-—-^

IGNITION COMPONENTS

- 1983 Models

Ignition Coil

Type/Model

I Version

Remarks

928 S

928 602 503 00 Bosch No. 0 221 122 001

With two ballast resistors 0.4 ohm and 0.6 ohm

Distributor

Type/Model

Version

Remarks

Bosch No. 0 237 401 018

Centrifugal and vacuum advance control. Distributor rotor without speed governor.

Spark Plugs

Type/Model

Version

Remarks

928 S

Bosch WR 8 DS Beru RS 35

0.7 + 0.1 mm

Control Unit

Type/Model

Version

Remarks

Bosch Mo. A 227 010 123

Transistor coil ignition

The distributor for USA/Canada models has a vacuum unit for advance control beginning with 1983 models.

221 122 001

IGNITION ADJUSTING AND TESTING VALUE BEGINNING WITH 1983 MODELS

Ignition timing (without vacuum)

20° BTDC at 3000 rpm

Idle speed

650 ± 50 rpm

Centrifugal control (without vacuum)

4 to 8° BTDC at idle speed; 24 to 28° BTDC at 5000 rpm

Vacuum control (at idle speed) "Advance"

Produce approx. 400 mbar with manual vacuum pump

13 to 17°

Ignition Adjusting and Testing Value, 28 - 29 1983 Models

THE USA PAGES 28 - 31 TO 28 - 34 HAVE BEEN LEFT BLANK.

IGNITION COMPONENTS - 1983 MODELS

Ignition Coil

Type/Model

Version

Remarks

928 S

928 602 503 00 Bosch No. 0 221 122 001

With two ballast resistors 0.4 ohm and 0.6 ohm

D istributor

Type/Model

Version

Remarks

928 S

928 602 033 00 Bosch No. 0 237 404 013

Centrifugal and vacuum advance and retard control. Distributor rotor with speed governor for 6500 — 260 rpm

928 S USA/Japan

928 602 032 06 Bosch No. 0 237 401 018

Centrifugal and vacuum advance control. Distributor rotor without speed governor.

Spark Plugs

Type/M ode I

Version

Remarks

928 S

Bosch W 7 D (175 T 30! Beru 14 - 7 D (175/14/3 A)

0.7 + 0.1 mm

928 S USA/Japan

Bosch WR 8 DS Beru RS 35

0.7 + 0.1 mm

Control Unit

Type/Model

Version

Remarks

928

928 602 702 02 Bosch No. A 227 010 123

Transistor coil ignition

The distributor for USA/Canada/Japan models has a vacuum box for advance control beginning with 1983 model.

IGNITION ADJUSTING AND TESTING VALUE - USA/CANADA/JAPAN BEGINNING WITH 1983 MODELS

Ignition timing

20° BTDC at 3000 rpm

(without vacuum)

Idle speed

650 ± 50 rpm

Centrifugal control

4 to 8° BTDC at idle speed

(without vacuum)

24 to 28° BTDC at 5000 rpm

Vacuum control

Produce approx. 400 mbar

(at idle speed)

with manual vacuum pump

"Advance"

13 to 17°

Ignition Adjusting and Testing Value — 28-33 USA/Canada/Japan (1983 Models)

CENTRIFUGAL ADVANCE CURVE TYPE 928 S - f r o m 1983 Models (USA, Canada, Japan) BTDC

Bosch Table Manual
0 500 1000 1500 2000 2500 3000 3500 Distributor Shaft Speed (rpm) ----^

VACUUM ADVANCE CURVE TYPE 928S-from 1983 Models (USA, Canada, Japan) BTDC

-l-

---------

-------

D

--

V)

*

(O - 01 -, o c to

. ..

A

7

r

-I-

-

EQUIPMENT TABLE - BEGINNING WITH 1984 MODELS

Ignition Coil

Type/Model

Version

Remarks

Bosch No. 0 221 118 322

Two ignition coils without ballast resistors

928 S 928 602 503 00

Bosch No.

USA/Japan i 0 221 122 001

I

With ballast resistors 0.4 ohm and 0.6 ohm

Distributor

Type/Model ! Version

Remarks

928 S

928 602 011 02

Double distributor (2x4 cylinders) with mutual drive shaft

Only high voltage distribution

Bosch No. 0 237 401 019

Centrifugal and vacuum advance control

Distributor rotor without speed governor

Spark Plugs

Type/Model

Version

Remarks

928 S

Bosch W 7 D Beru 14 - 7 DU

0.7 + 0.1 mm plug gap 0.7 mm plug gap

928 S USA/Japan

Bosch WR 8 DS Beru RS 35

0.7 mm plug gap

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    WHAT IS THE RESISTANCE ON BOSCH COIL 0221122001?
    6 years ago

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