Engine Management System Simtec 70 Opel Vectra B

Simtec 70 Engine Management System

The X 18 XE1 DOHC petrol engine is fitted with the new Simtec 70 engine management system which is based on the familiar Simtec 56.6 in the X 18 XE.

The table below lists the differences between the Simtec 56.6 in the X 18 XE and the Simtec 70 in the X 18 XE1.

Engine Compartment Survey

1. Tank vent valve 4 Exhaust gas recirculation valve
2. Throttle valve adjuster 5 Ignition module
3. Engine control unit 6 Camshaft sensor

4.2.16.1 Engine Compartment Survey

1. Hot film mass air flow meter 4 Oxygen sensor
2. Knock sensor 5 Coolant temperature sensor
3. Injection valves 6 Crankshaft pulse pick-up

Engine Control Unit

The engine control unit for the X 18 XE1 is constructed according to a compact composite design and is secured directly to the intake manifold module in the engine compartment.

The engine control unit has separate wiring harness plugs for the body wiring harness and the engine wiring harness. There are individual recesses on the control unit (mechanically coded) and on the wiring harness plugs in order to avoid confusing the wiring harness plugs.

Crankshaft Pulse Pick-Up

The crankshaft pulse pick-up (1) is responsible for determining the speed of the crankshaft. The crankshaft pulse pick-up measurement is based on inductive principles. The induced voltage curve is thus directly proportional to the speed of the increment disc.

In the X 18 XE1, the crankshaft pulse pick-up is installed on an oil pump lug, the torsional vibration damper (increment disc) being used to determine the speed.

The crankshaft pulse pick-up transmits a signal to the engine control unit which calculates the crankshaft speed from this signal.

Camshaft Sensor

The camshaft sensor (Hall sensor) is used to record the camshaft position and it enables the cylinder to be recognised - which is necessary for sequential injection.

Two segments are attached offset to the camshaft pulley for the exhaust camshaft.

The camshaft sensor comprises two Hall elements (1, 2), each element being responsible for one segment. As a result, the camshaft sensor can recognise the position of the camshaft as early as at ignition "ON", i.e. before starting.

The exact quantity of fuel can be assigned to the appropriate cylinder even for the first engine revolution with this fast-start system. Emergency operation is possible via the camshaft signal if the crankshaft pulse pick-up fails.

The segments are on the front side of the exhaust camshaft pulley.

1. Hall element for outer segment
2. Hall element for inner segment

Signal Assignment for Crankshaft Pulse Pick-Up and Camshaft Sensor

The pulse pick-up disc (increment disc) is designed as a gear with 58 teeth. The gap between teeth is as wide as two teeth. The signal for the first falling tooth flank (1) of the pulse pick-up disc after the tooth gap is 114� CA CA: Crankshaft angle before the TDC TDC: Top dead centre of the 1st/4th cylinder (2).

The TDC of the 1st cylinder follows 78� CA after the rising flank (4) / the TDC of the 4th cylinder follows 78� CA after the falling flank (3) for the signal profile of the camshaft pulley with the segments attached at 180� displacements.

Throttle Body

The X 18 XE1 features a new throttle body with a fully electronic throttle valve adjuster (2) as well as a throttle valve potentiometer (3) being integrated.

The idle speed is controlled by the position of the throttle valve in the main flow, controlled by the throttle valve adjuster.

The throttle valve is adjusted mechanically using the accelerator Bowden cable when the accelerator is pressed down.

• Wiring harness plug
• Throttle valve adjuster
• Throttle valve potentiometer

When the throttle body or engine control unit has been replaced, it is essential that the adaptation values for the throttle valve in the EEPROM of the engine control unit are deleted using TECH 2 - see corresponding Checking Procedures.

Hot Film Mass Air Flow Meter

The hot film mass air flow meter is the most important component for calculating the load signal. It is also called the "thermal load sensor".

The hot film mass air flow meter uses a two-sensor element. The first sensor (R T ) measures the intake temperature and the second sensor (R S ) measures the mass air flow.

The combination of the two sensors, with the aid of a bridge circuit (R 1 and R 2 ), enables the intake temperature measurement to be decoupled from the mass air flow measurement.

At the air intake of the mass air flow meter there is a honeycomb element (1) and a grille (2) in order to maintain a uniform flow past the sensors.

Ignition Module

The ignition module in the X 18 XE1 is located between the two camshafts directly above the spark plugs and consists of the following components:

• Wiring harness plug from the engine control unit
• One single ignition coil for each cylinder
• Integrated spark plug connector

The ignition coils supplied by the engine control unit with a lower voltage supply the spark plugs with the high voltage necessary for the ignition at the appropriate moment.

Observe the safety regulations when using high-voltage-bearing parts.

Injection Valves

The injection valves are fitted with 2-hole nozzles for the X 18 XE1, one jet for each intake valve.

The two-jet valve with multi-hole metering is provided with a nozzle hole disc (2 calibrated bores). The holes are aligned in such a manner that this produces two injection jets.

As the X 18 XE1 is not fitted with a fuel return, the injection valves operate at an increased pressure (3.8 bar) in order to compensate for condensation or evaporation of fuel when starting.

Block Diagram

4.2.16.10 Block Diagram