Fuel and exhaust systems - Mono Jetronic fuel injection

The Mono-Jetronic central fuel injection system is fitted to the 1.8 litre (code RP) engine. It is a simplified method of fuel injection (see illustrations). Fuel is injected into the inlet manifold by a single solenoid valve (fuel injector) mounted centrally in the top of the injector unit housing.
The length of time for which the injector remains open determines the quantity of fuel reaching the cylinders for combustion. The electrical signals which determine the fuel injector opening duration are calculated by the Electronic Control Unit (ECU) from information supplied by its network of sensors. Fuel pressure is regulated mechanically.

The signals fed to the ECU include the following:
a) The engine coolant temperature
b) The engine speed and crankshaft position - from the distributor
c) The position of the throttle valve plate - from the throttle position sensor
d) The oxygen content in the exhaust gases - via a sensor (Lambda probe) in the exhaust manifold
Using the information gathered from the various sensors, the ECU sends out signals to control the system actuators as required. The ECU also has a diagnostic function which can be used in conjunction with special VW test equipment for fault diagnosis. With the exception of basic checks to ensure that all relevant wiring and hoses are in good condition and securely connected, fault diagnosis should be entrusted to a VW dealer. Basic testing can be carried out on the system components covered in the following text. More detailed testing can be carried out by using specialised equipment but this must be entrusted to a VW dealer.

Download

CS1000 Fault Code Scanner BMW Instructions

All 1989-94 BMW vehicles are equipped with a self diagnostic system for the detection of injection faults. When a fault is detected by the system the Electronic Control Unit (ECU) records the code corresponding to the defect in the ECU's memory until either:
1) The vehicle battery or the ECU is disconnected.
2) The engine is started 60 times with no recurrence of the fault.
3) The ECU memory is cleared using the BMW MODIC, DIS, Bosch KTS300, KTS500, or the Baum Tools CS1000 or CS2000 BMW hand held scanner.

To review the FAULT CODES from the ECU memory use the following procedure:
1) Turn the ignition switch to the 'engine run' position.
2) Depress the gas pedal to the floor 5 times.
The CHECK ENGINE light will blink out the FAULT CODES starting with the lowest number first. These FAULT CODES consist of 4 digits each separated by a short pause (ie. blink pause blink blink pause blink pause blink translates as 1 2 1 1)

Download