Outer Limits 4x4 Board

RaginRover wrote:you afm probably needs adjusting back to spec - you need to find out what resistance it needs to be running and adjust the trim pot (assuming it has one) accordingly

Tony aka RUFF has just been working through this I think he found the specs on the Land Rover Owners Forum (uk I am guessing) on the vitesse AFM does it have any numbers on it like 3AM, 5AM or something - I can't picture the unit you are taking about

Tom

RaginRover wrote:While we were testing things I found this info


Air temperature sensor
Possible fault:

Incorporated in the air flow sensor

Connect ohmmetre between Pins 6 and 27

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

Tom

Thanks to
http://www.landroverclub.net/Club/HTML/ECU_check.htm
for the info.

Harry wrote: All the way in clockwise then out 2.5 turns anti-clockwise puts it in the start position for setting up the base idle of around 500rpm, it could be a turn either way away form this IMHO.
As Peter has said, perhaps you should raise it (anti-cw) a little more to stop it stalling until you get a permanent solution.

Harry

Andy M wrote: Idle Speed Dropping (Maybe Stalling)?

I can start the car from cold, drive all day in stop start traffic or on a clear run and the car accelerates smoothly and holds a rock steady 950rpm idle. However, if I stop and have to turn the ignition off the problems start. On re starting the engine hot whenever the car comes to a standstill the idle speed drops to around 150 - 300rpm, the engine hunts and appears as though it will stall at any moment although it doesn't. 3 to 4 seconds later the idle speed slowly rises to 950rpm and will then idle happily for as long as I am stationary. If I move off then come to a standstill again the same thing happens all over again. If I come to a stop with any kind of steering lock on the additional load of the power steering pump causes the car to stall. Once the engine has cooled I can re start and the car performs perfectly.

I suspect I should be looking at the stepper motor / potentiometer but am unsure how to check for correct operation. I don't think it will be easy to check whilst the problem is occurring as it corrects itself within 3 to 4 seconds. Some help here would be useful.

Thanks

Steve.

Sounds like the base idle speed is too low and the ECU is using the stepper motor to hold the idele speed at 950 rpm. Most 1990 820Si use Lucas "Hotwire" Efi, the means of adjusting the 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 maual for the Montego 2litre Efi.

Type (1) has an external stop screw acting directly on the throttle butterfly spindle -- this is the type shown in the Haynes manual.

Type (2) has an adjusting screw regulating the throttle by-pass passage. This located on the same side as the idle mixture adjustment screw but about 30mm towards the front of the throttlebody and about 10mm lower down.. Both this and the mixture adjustment screw might be sealed by an alloy plug.

Before attempting any adjustment check thr connections to the water temperature sensors and the fuel temperature sensors are in good order, also check the litte rubber vacum pipe to the ignition ECU is clear and in good order, likewise the airfilter should be fairly clean.

Assuming the rest of the engine is in good order now get the car fully warmed up -- the electric fan should be allowed cut in and cut out again. The next stage is to cycle the idle speed stepper motor to the base idle position.

(1) Switch on the ignition (2) count to 10 (3) Disconnect the stepper motor plug (the black "spark plug like" object on top of the throttlebody). (4) Switch off the ignition (4) Count to 10 (5) Reconnect the stepper motor

Repeat steps 1 to 5 THEN repeat steps 1 to 4 DO NOT RECONNECT AT THIS STAGE

This should leave the stepper motor in the base idle position (ie. fully extended and the by-pass valve will be fully closed) You may may now start the car and adjust the base idle speed. This should be 750 RPM +/- 25 RPM. However beware Rover dashboard tachos are often pretty inaccurate. Switch off then ignition and reconnect the Stepper motor, the idle speed with the ECU controlling the stepper motor should be 950 RPM but may tend to rise above this.

If this procedure dosen't work try (1) Cleaning out the throttlebody and the little pipe to the airfilter. (2) Clean and lubricate the stepper motor with wd40 (3) Check the temperature sensors and Thermostat.


For information on setting up Rover fuel injection and measuring the various sensors http://www.davrian.freeserve.co.uk/roveridle.htm

Andy M

RUFF wrote:I just sorted mine out this afternoon. I found all the specs i needed on the AULRO forum http://www.aulro.com/modules.php?name=Forums I fitted a 97 disco motor complete with EFI to my 86 about a year ago and since then its been running with a dead Airflow Meter but only real;ised a few weeks ago this was the problem it was having. I replaced this a week or so ago and it ran better but today i found the specs to set it correctly. You need to get a digital Multi Meter(A non digital one can cause problems to the afm apparently) And probe the far left terminal and the far right terminal on the AFM with it disconected then adjust the trim pot to 174ohms. This will set it back to factory settings.