New Engine C 18, OHC Engine Opel Vectra A

Subject: New Engine: C 18 NZ, OHC Engine

Vehicles: Vectra/Cavalier,

Kadett-E/Astra/Belmont

The C 18 NZ engine will be added to the existing engine range as of Model Year 1990 1/2 in the Vectra/Cavalier and as of Model Year 1991 in the Kadett-E/Astra/Belmont. This Technical Information Bulletin contains data specific to the engine and information about components for the new C 18 NZ engine; more detailed information will be included in the next revised editions of the Vectra/Cavalier and Kadett-E/Astra/Belmont Service Instructions, and will also be published in the "OPEL/VAUXHALL Multec Central Fuel Injection (C 18 NZ)" Checking Procedures.

The engine is equipped with a Multec mixture preparation system. The main differences between this and the familiar "Multec engines" are:

- High voltage distributor, no ignition basic adjustment necessary;

- Bidirectional data lead (like C 14 NZ engine),

Actuator test with TECH 1: Idle speed control stepper motor,

injection valve,

ignition coil,

fuel pump relay;

- Engine speed signal and TDC signal determined by inductive pulse pick-up and segment disc with 58 teeth and gap (2 missing teeth).

- New control unit with replaceable program memory (similar to C 16 NZ); - Modified terminal assignment.

The Multec C 18 NZ engine can be checked with the Program Module, "OPEL/VAUXHALL 89-90 ECU".

1) MSTS-i = Microprocessor Spark Timing System, inductively triggered

2) Values for Kadett/Astra/Belmont not available at the time of publication.

The most important system components are described below:

Multec control unit

Checking with TECH 1, Program Module "OPEL/VAUXHALL 89-90 ECU" possible.

Installation position

Below glove compartment, behind trim of door pillar.

The control unit is only inserted and not bolted in.

Replace program memory by pressing the two side catches and pulling.

Parts numbers and codes, see table on page 8

Exhaust gas recirculation system

The exhaust gas recirculation system of the C 18 NZ consists of

- exhaust gas recirculation valve

- vacuum line.

Installation position: on intake manifold.

The system corresponds to the exhaust gas recirculation of the C 16 NZ engine.

Oxygen sensor

(unheated)

Tightening torque: 30 Nm/22.1 ft. lbf.

Coat thread with Special Grease

Catalogue No. 19 48 602 - 05 613 695.

Coolant temperature sensor

Identification: blue base;

NTC resistance, as for all Multec.

(NTC = negative temperature coefficient)

Inductive pulse pick-up

Supplies engine speed signal and TDC signal to control unit.

Schematic representation

1 Inductive pulse pick-up

2 Segment disc

(with 58 teeth and a gap of 2 missing teeth)

Inductive pulse pick-up

Installation position

Octane number plug, diagnostic plug

1 Octane number plug

2 Diagnostic plug

3 Relay box

Octane number coding

Control unit/program memory

* Data not available at the time of publication.

1) Parts and Accessories supplies under this Catalogue No. the control unit without program memory

Diagnosis with TECH 1

The following new features must be observed when checking with Program Module OPEL/VAUXHALL 89-90 ECU:

- Temperature sensor

Besides temperature, voltage is also displayed.

- Throttle valve potentiometer

Besides voltage, the aperture angle is also displayed in %.

- O2 Partial Load Block

Learn Via the O2 Block Learn for partial and full load, learned deviations from the ideal mixture condition (e.g. caused by engine friction, leaking air, changes in the density of the air, etc.) are captured by the control unit and stored in the permanent memory.

This correction value corresponds to the already familiar O2 BLM IDLE THR. value, but is valid in the engine speed range above 1200 rpm.

- Air/fuel ratio

Shows the air/fuel mixture (rich/lean) dependent on the oxygen sensor voltage.

- Acceleration enrichment,

- Lean mixture for starting

Information values. Serves to increase comprehension of the system and are not used for actual trouble-shooting.

- Vehicle speed sensor

Display: No reception/reception OK

Actuator Test, Multec C 18 NZ:

Carried out with Program Module OPEL/VAUXHALL 89-90 ECU, mode F5.

Trouble Code

Trouble Code, Delete: With TECH 1: Press key F 4.

Without TECH 1: The trouble codes stored in the control unit can be deleted by disconnecting the vehicle voltage supply.

If TECH 1 is connected to the diagnostic plug, the engine telltale in the vehicle illuminates, even if there is no fault stored (modification as of MY 91: when TECH 1 is connected, the engine telltale no longer illuminates automatically.

Faults are recognizable).

Trouble Code Table:

Terminal Assignment of Control Unit (24-pin)

A1 Unoccupied

A2 Reference lead to engine speed sensor P 35 Ter. 2

A3 Unoccupied

A4 Unoccupied

A5 Unoccupied

A6 Unoccupied

A7 Signal lead of intake manifold pressure sensor P 23

A8 Signal lead of throttle valve potentiometer P 34

A9 Unoccupied

A10 Unoccupied

A11 Ground lead of vacuum sensor P 23 and of coolant temperature sensor P 30

B1 Permanent voltage supply for fault memory

B2 Signal lead of odometer frequency sensor

B3 Reference lead from engine speed sensor P 35 Ter. 1

B4 Fuel consumption signal for board computer

B5 Throttle valve position output signal to AT

B6 Switched ground of control unit K 100 to fuel pump relay K 58 Ter. 85

B7 Diagnostic excitation lead from diagnostic plug X 13 Ter. "B"

B8 Supply voltage of throttle valve potentiometer P 34 and intake manifold pressure sensor P 23

B10 Ground for oxygen sensor

B11 Signal lead of oxygen sensor

B12 Signal lead of coolant temperature sensors P 30

Terminal Assignment of Control Unit (32-pin)

C1 Switched ground for engine telltale H 30

C2 Engine load signal to control unit K 85 Ter. 25

C3 Unoccupied

C4 Voltage supply of control unit K 100 Ter. 15

C5 Lead to coil 2 of servo motor M 33 Ter. "C"

C6 Lead to coil 2 of servo motor M 33 Ter. "D"

C7 Unoccupied

C8 Lead to coil 1 of servo motor M 33 Ter. "B"

C9 Lead to coil 1 of servo motor M 33 Ter. "A"

C10 Ground pulse of injection valve Y 32

C11 Unoccupied

C12 Unoccupied

C13 Unoccupied

C14 Unoccupied

C15 Unoccupied

D1 Final stage ground of injector

D2 Ground lead, throttle valve potentiometer P 34 and ground lead, octane number plug X 15

D3 Unoccupied

D4 Unoccupied

D5 Unoccupied

D6 Unoccupied

D8 Bidirectional data lead from ALDL plug Ter. "G"

D9 Signal lead, P/N switch (AT only, otherwise ground)

D10 EST signal to igntion final stage K 20 Ter. 4

D11 Octane number plug

D12 Unoccupied

D13 Unoccupied

D14 Unoccupied

D15 Unoccupied

D16 Ground pulse of injection valve Y 32

Circuit Diagram VECTRA/CAVALIER 1)

F 11 Fuse (in fuse box) 997

K 20 Ignition module, ignition coil 975..976

K 58 Fuel pump relay 998..997

K 85 AF 14/20 transmission control unit 771..797

K 100 Multec control unit 978..998

L 1 Ignition coil 974..975

M 21 Fuel pump 997

M 33 Idle speed stepper motor 985..988

P 23 Absolute pressure sensor 984..986

P 30 Coolant temperature sensor 982

P 33 Oxygen sensor 991

P 34 Throttle valve potentiometer 987..989

P 35 Pulse pick-up, crankshaft 962..984

S 10 Transmission switch 770..776

Y 32 Injection valve 979

Y 33 Ignition distributor 972..974

X 5 Plug, instrument panel and engine, 14-pin 975

X 8 Plug, instrument panel and Multec, 2-pin 997

X 9 Plug, instrument panel and Multec, 6-pin 993..994

X 11 Plug, instrument panel and Multec, 6-pin 992..993

X 13 Diagnostic plug, 10-pin 992..993

X 15 Octane number plug, 3-pin 991..993

X 81 Plug, engine and Multec, 1-pin 975

1) The Kadett-E/Astra/Belmont C 18 NZ circuit diagram is not available at the time of publication.