Check Flapper AFM Engines

This procedure should be similar on any engines using a flapper Air Flow Meter and a Lucas ECU. The Hot Wire system is slightly different. This procedure has been used successfully on many cars but it's at your risk. You can damage a component beyond repair if you screw it up.

This is presented in the normal checking sequence.

WHAT SOME ITEMS LOOK LIKE

Please note that there ius a large earlier one (no longer available) and a later smaller one (used for many years). To use the later one and earlier owner will have to buy a new plenum to fit it.
Cold start enrichment Connector to the ECU P= pump relay

M=main relay

S="steering" (CONTROL) relay

 Air flow sensor - connector Throttle Potentiameter
Resistance Module box Timed thermal contact Air mixture valve Coolant temperature sensor Coil

 

Feeding of the ECU Possible fault:
Connect multimeter (on volts) between Pin 10 and ground. Contact. No reading: Check cables and connectors, check Main relay by substitution of a new unit (this muts be a genuine Landrover 30amps, 0332 014 113)

Lower than 11 V: Check cables and connectors for a bad or corroded contact
Normal result:
11-12.5 Volts
  

 
Fuel pump contacts Possible fault:
Connect multimeter (on volts) between Pin 20 and ground.with Air flap closed When closed: Something else than =V when flap closed: check switch on air meter (flap) housing 

When moving: No reading: Check wire harness from relay to air metre, then from air metre to relais of fuel pump. Check the relay by substitution of a new one. Check the pump by connecting a wire directly from battery + and - to the pump
You will often find that the last works. The airflow meter has a trigger that signals the pumpmreolay to work. This was meant to prevent the pump from functioning if the engine as not. It often fails. Many wire the pump to the ignition. This is NOT the safest solution but it works.
 
Normal result:
0 V when closed, 11-12.5V when flap moving
  

 
Starter rotation signals
 Possible fault:
Connect multimeter (on volts) between Pin 4 and ground. Turn the engine over with the starter.  No reading but starter turns: Check wiring harness from ECU to relay and electronic regulator

No reading and starter does not turn: check starter and starter relay.

Reading under 8V: check battery (connect another one) and starter
Normal result:
8-12V
  

 
Air Flow Meter
 Possible fault:
Connect multimeter (ohms):

between Pin 6 and 8: 360 ohms 

between Pin 6 and 9: 560 ohms 

between Pin 8 and 9: 200 ohms 

 Differing values: check cables with ohmmetre, check AFM flap to make sure it's completely closed.
Normal result:
above values + 10 ohms
  

 
Water temperature sensor
 Possible fault:
Connect multimeter (Ohms) between Pin 13 and ground Different values: Check cables and connector, change sensor if readings still differ

Take only short readings as sensor may be damaged by heat from the multimeter's current
Normal result:
-10°C = 7-11,6 kohms

+20°C = 2,1 to 2,9 kohms

+80°C = 0,27 to 0,39 kohms

  

 
RPM signal
 Possible fault:
from COIL

Make a connection between negative post of the coil and Pin 1. Connect multimeter (volts) between Pin 1 and ground

Please notew that the siugnal from the negative post of the coil goes to the tachometre and then the ECU. Without it..the car will not start.

 No reading: check the connectors between coil and regulator
Normal result:
Fluctuates between 6 and 9V
  

 
 
Injectors
    Possible fault:
Injector 7 Connect multimeter (ohms) between Pin 14 & 87 of main relay  Reading below normal: Disconnect one injector after another  until you find the one with low or 0 resistance. Replace it 

If all are OK you must check the wiring harness and connectors as well as the resistance module
Injector 8 Connect multimeter (ohms) between Pin 28 & 87 of main relay 
Injector 2 Connect multimeter (ohms) between Pin 31 & 87 of main relay 
Injector 4 Connect multimeter (ohms)e between Pin 30 & 87 of main relay 
Injector 3 Connect multimeter (ohms) between Pin 33 & 87 of main relay 
Injector 5 Connect multimeter (ohms) between Pin 32 & 87 of main relay 
Injector 1 Connect multimeter (ohms between Pin 15 & 87 of main relay 
Injector 6 Connect multimeter (ohms) between Pin 29 & 87 of main relay 
Normal result:
Between 7 and 10 ohms
  

 

A fuel pressure gauge for testing
Injection ramp
 Possible fault:
Mount the guage on the flexible line to the cold start enrichment injector. Turn ion the ignition and move the AFMr flap to close the electric circuit to the fuel pump Pression 0: Check if fuel pump gets 12V, if not so replace the  pump relay and then the main relay.

If the pump gets 12 V check it's ground (a common fault) by laying a wire directly to the ground. If it still does nothing chances are good the pump is shot. Take it out and check it again on the bench.

Pressure out of limits (above or below): Check for leaks on the complete circuit, coloring around line connections and leaking injectors, then fuel pressure regulator and anti-return valve-in this order.
Normal result:
2,4 to 2,6 kg/cm2]
28-36 pounds with the engine off
  You can have the pumpo fiunction by having the ignition on and deflecting the flap in the AFM

 
Lambda (Oxygen) Sensors
(not onMorgan Flappers)
 Possible fault:
Connect multimeter (ohms)  between Pin 34 and 87 of the fuel pump relais No reading: Check wiring and connectors between fuel pump relay and air mix valve as well as electronic regulator. Than disconnect valve and check it by ohmmetre
Normal result:
30 - 40 ohms
  

 
Cold Start injector
(on the plenum in back)
 Possible fault:
Disconnect thermotime switch. Successively ground the wires. Connect multimeter (ohms) between Pin 4 and ground No reading: Check wiring and connectors between ECU, cold start injector and thermotime switch.

Cut off: Check wires, connectors and cold start injector
Normal result:
0 - 5,0 ohms
  

 
Air temperature sensor
 Possible fault:
Incorporated in the air flow sensor

Connect multimeter (ohms) between Pins 6 and 27

Take only short readings as sensor may be damaged by heat from curent from multimeter

 Reading unlimited: disconnect flow meter, connect Pins 6 and 27. If reading is now 0 the sensor is faulty. If reading still unlimited check wiring and connectors as well as ECU connector
Normal result:
-10°C: 8,26 to 10,56 kohms

+20°C: 2,28 to 2,72 kohms

+50°C: 0,76 to 0,91 kohms

  

 
Air flap position sensor
aka Throttle Potentiameter
 Possible fault:
Set multimetre on ohms, reconnect ECU, contact  
Measure volts between green (-) and yellow (+) by the back side of the connector block near the ECU 4,3 (+- 0,2V)

Lower or 0: check wiring and connectors
Measure ohms between green (-) and red (+) by the back side of the connector block near the ECU 0.325 (+0.35)

Loosen screws and rotate (fiddle) sensor until reading is correct
The reading must increase steadlily progressively as you open the air flap Progressive from 0,3 to 4,5V

If the reading jumps or fluctuates you must change the sensor.

 
Deceleration shut off relais
 Possible fault:
Disconnect the - wire from coil to relay. Contact off. Connect multimeter (ohms) between Pins 1 and 30 of the relais Unlimited is correct. Anything else: Check wires and connectors, then replace relais by a new one.
Contact The resistance must drop to 0. Anything else: Check wires and connectors, maybe even the vacuum switch.
Repeat the measurement at least once.  

 
Airflow Meter
 Possible fault:
Reconnect ECU. Contact. Pull back the rubber sleeve on the connector. Connect multimeter between Pin 6 (+) and Pin 9 (-) 1,55V (+- 9,1V) This figures from the genuine book but I strongly suspect a fault here. I think it should read +-0,1V
Connect multimeter between Pin 9(-) and Pin 7(+) 3,7V +-0,1V
Open the flap slowly: The tension must drop 1,6V +-0,2V
Abnormal results: Change the sensor

 
Airflow Meter
 Possible fault:
Disconnect ECU. Contact. Pull back the rubber sleeve on the connector. Connect multimeter between Pin 8 (+) and Pin 9 (-) Abnormal reading: Change AFM, (if you can find one)
Normal result:
4,3V +- 0,2V