Modern Engine Management

[Mr Teddy Bear]

Back in the 70's I took all the C&G exams going in Motor Vehicle Engineering
all the way to Tech' level.
How ever I don't know a great deal about all the modern systems,especially
ECU controlled Engine Management Systems. Owner Manuals don't cover
the theory of fuel injection or cold starting enrichment. Engines running either
lumpy (weak mixture ) or hunting (to rich) seem to be characteristics of the past.

So what has replaced the Choke Assembly ?

This is a genuine question designed to stimulate discussion not sarcastic
comments aimed at particular people please.

Tim:roll:

 

[television]

Back in the 70's I took all the C&G exams going in Motor Vehicle Engineering
all the way to Tech' level.
How ever I don't know a great deal about all the modern systems,especially
ECU controlled Engine Management Systems. Owner Manuals don't cover
the theory of fuel injection or cold starting enrichment. Engines running either
lumpy (weak mixture ) or hunting (to rich) seem to be characteristics of the past.

So what has replaced the Choke Assembly ?

This is a genuine question designed to stimulate discussion not sarcastic
comments aimed at particular people please.

Tim:roll:

The more up market carb systems had a starting carb, rather than the choke, I even had a starting carb on my 1928 Rolls.

Injection system have a fuel enrichment device, often linked to the ignition switch / starter motor and controlled be engine temperature and air sensors.

So in a way the enrichment device is similar to the starting carb . My description is what followed carbs, Ulymate in the thread below has described the next move and the way things are now.

 

[Ultymate]

The ECU receives information from engine sensors ie engine temp and ambient air temp and then the ECU varies the dwell angle of the injectors ie the amount of time the injectors will be held open, the longer they're open the more fuel is supplied, at the same time an excess air device is also brought to life by the ECU to feed a matching amount of air to up the idle speed for warm up. Some engines also feed air into the exhaust whilst warming up in order to fascillitate faster warm up of the catalytic converter. As a final point some cars do not have timed injection ie the injectors spray continuously just outside the inlet valves whilst the more sophisticated have timed injection for this the engine needs a cam sensor to feed the ECU with info on the position of the valve gear so as to be able to time the injection. Hope this helps