Rover Holic

Rover 820 Lucas ECU Ignition System
Lucas ABU 17 Ignition ECU Pinout

Ignition ECU Pin No.
Function
Wire Colour
 Remmarks

1

Rover 800 and 820  models with Lucas Hot wire Efi

Early Rover 820I, 820Si models use Lucas "Hotwire" Multipoint Efi, the means of adjusting the base idle speed varies according to the type of throttlebody fitted. Only one type is shown in the Haynes manual for the 800 although details of the other type are given in the Haynes manual for the Montego 2litre Efi.

Throttlebody Types:

Lucas Hotwire MPi
Stepper Motor Idle Speed Control

The idle speed on this system is controlled by the Fuel ECU via a stepper motor actuated throttle by-pass valve. This maintains a minimum idle speed of 950 RPM (900 RPM on cars with automatic transmission) which is 200 RPM above the base idle speed when the engine is fully warm. The ECU will raise the idle speed above this if the engine is cold or the fuel temperature is excessively high, it may also raise the idle speed if a fault condition is detected.

Rover 820 Mpi Lucas Hotwire Efi: Fuel Temperature Sensor

If removing this component allow the fuel rail time to depressurise and the engine time to cool to reduce the danger of a serious fire before slackening even then cover the union with a cloth as you slacken the fitting.

Location: In centre of fuel injector supply rail, at the rear of the engine above inlet manifold.

Function: To supply information to fuel ECU on fuel temperature, to prevent vapour locking of the fuel injector system.

Sensor Information Rover 820 Models
Lucas Hotwire Multipoint EFI
All values measured on 1990 Model 820Si.
The sensor fitted to Rover cars using the MEMS ECU  and also the Honda 2.5 & 2.7 litre V6 appears to have similar electrical characteriestics.
Coolant Temperature Sensor (CTS) for ECU.
(information provided for general guidance only)

Location: On thermostat housing.

Description: Sensor plug has plug with two blade connections.

Rover 820Sli Lucas Hotwire Mpi
Hotwire Airflow Sensor Output - RPM
Conditions: Full Throttle  - Accelarating Up Incline
Ambient Temperature 16 C

Rover 820 Lucas Multipoint Injection: Hotwire Air Flow Sensor
(applies to Lucas EFI equiped cars only)

Description:
Hotwire  type sensor, the actual  "hotwires" taking the form of film type semiconductor resistors.

Location:
Located in inlet duct between the throttlebody and air filter, a 3 pin connecting plug to wiring loom is located below inlet duct.

                                                                            Lucas Hotwire Mpi

   1.  If you have established there is no spark at the plugs before doing anything else check the cam belt isn't broken -- if the belt is broken rotor arm won't be turned by the camshaft
   2. Carefully examine the coil, distributer cap and leads for cracks or signs of damage.

Be aware of the dangers of acid splashes and of explosive gas build up when working near batteries especially when charging and testing and also take care not to short out the battery.

   1. Before attempting to test any alternator it is essential to ensure that the battery is at least a 75% charge, and also the battery is in good condition and has no dead or shorted cells. Even when working perfectly an alternator cannot charge a battery which is almost completely flat.