AIUI...
This is a very basic system which is trying to mimic a twin choke carburettor.
The quantity of fuel injected is determined by the following:
throttle position (there are two tracks on the potentiometer - one to correspond with each of the 'chokes': the second one doesn't come into play until the throttle is part open.)
engine speed
inlet air temperature
coolant temperature
lambda sensor voltage (when warmed up)
The idle speed is adjusted automatically (using the stepper motor on the butterfly valve) under the control of the ECU.
When you turn the key to ignition on, just prior to a cold start, you may hear the stepper motor open the throttle a bit - you may even see the pedal go down a bit, if the cable is tight.
There isn't anything you can set: if it's all working as intended the ECU will take a stab at an ammount of fuel to inject, and if the engine is warm and the lambda sensor is switching, the ECU will correct this guess to maintain the correct gas mixture into the catalyser (on average).
When cold (ATS and CTS the same value, and no lambda switching) the ECU will juggle throttle position and fuel to give a slightly fast tickover.
On the mono-jetronic the ignition is totally separate from the injection (so no MAP sensor), but there is the vacuum advance to the distributor ot advance the spark on light throttle.
Check the advance cartridge - it fails and you get very flat performance and poor economy.
Give it a really heavy dose of injector cleaner, and a full set of clean filters, including the fuel filter.
That's about it - anyone else care to add, or contradict anything??
John H

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