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I remember when I took shop class and they taught me that you need just three things to get an engine running, spark, fuel, and compression. Well, I read the following on AllData and I just though some of you might like to read what goes on behind the scenes when you turn the key on your MINI.
Powertrain Management: Description and Operation Principle of Operation
Principle of Operation
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Operation of the Engine Management System is broken into 6 subsystems. These subsystems are:
- Power Supply
- Air Management
- Fuel Management
- Ignition Management
- Emission Management
- Performance Management
Power Supply
------------
When the ignition switch is placed in the KL 15 or KL50 positions, Fuse 34 is provided with power. Fuse 34 supplies the wake up or on signal to the EMS2000. Upon receipt of the "ON" signal EMS2000 supplies a ground signal on Pin 97 to the Main Relay. The ground signal energizes the Main Relay, supplying operating power to the following fuses:
The EMS2000 sees engine cranking through the crank sensor. It checks the PWG and should see 0.5 volts on both inputs indicating request for idle. The feedback potentiometers are checked in the EDR to confirm throttle plate position. Signals of 0.5 volts from Pot I and 4.5 volts from Pot 2 indicate the throttle plate is in the LL or idle position.
With the engine now cranking the EMS2000 looks at inputs from the TMAP (and Map, if a COOPER S). TMAP volts drops from 4 volts toward the high vacuum voltage reading of 1 volt. A voltage of 5 volts or 0 volts puts the EMS2000 in Fault Mode. A fault is registered and air volume information is derived from a default map.
Intake air temperature is checked, 4 volts indicating a cold air, 1 volt or less hot air.
From the TMAP and Intake air temperature the intake air volume and density is calculated.
Fuel Management
---------------
Seeing engine revolutions the EMS2000 provides a ground signal to the Fuel Pump Relay. The fuel pump relay is on a fused circuit further protected by the Inertia Switch. If the inertia switch is not triggered (triggered = open) power is provided to the fuel pump relay.
Receiving power the fuel pump, mounted in the swirl pot of the left side of the blow molded saddle type fuel tank, picks up fuel through the life time fuel filter and passes it to the right side tank. In the right tank the fuel is passed through a pressure regulator where a fuel pressure of 3.5 bar is maintained. Excess fuel is returned from the right tank to the left tank through a siphon jet that also transfers fuel to the left tank.
Fuel at 3.5 bar is sent to the engine mounted fuel rail assembly. The fuel rail contains the pressure damper to smooth out fluctuations in fuel pressure during high load situations. Based on the volume and density of the air, the engine load, engine rpm and temperature, the EMS2000 calculates the correct volume of fuel for injection. Monitoring the crankshaft and camshaft sensors the EMS2000 decides upon the proper timing of the fully sequential injection. Failure of the camshaft sensor causes the EMS2000 to inject fuel on a semi-sequential basis (injectors are triggered every engine revolution). Failure of the crankshaft sensor causes cancellation of fuel injection.
Ignition Management
-------------------
The firing cylinder has the proper air/fuel ratio, now ignition must be optimized for performance and emissions.
The EMS2000 again relying on previously analyzed sensor inputs, decides upon the correct time for ignition coil firing. As the engine approaches TDC, the EMS2000 grounds the appropriate output stage and fires the ignition coil, then listens through the knock sensor for variations in engine sound.
The spark plugs introduce the ignition energy into the combustion chamber. The high voltage "arcs" across the air gap in the spark plug. This creates a spark which ignites the air/fuel mixture.
Think of it as a beaurocracy installed behind the scenes that oversees the simple stuff. With any such beaurocracy, it makes things sounds (and be) more difficult than in the past.
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JCW Intake|15% Alta|Milltek Catback|17x7.5 SSR Comps|215/45-17 GS-D3s|Much More
MMC #28|Motoring ID RAGE666
With such complexity in simple tasks you can see how dependent new cars like the MINI are on modern electronics and the computer (ECU). It also means that many things can go wrong and need fixing and when you are trying to make improvments in the ECU program there are many considerations.
Definitely not stuff for the do it yourself person to make changes to and expect anything good without causing damage elsewhere.
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#43 Street Modified (SM) Class SCCA Hawaii Region
2005-2009 Solo Run Off and Points Champion (Hawaii)(2nd 2006 Points)
2005-2008 Overall PAX: 8th 2006, 7th 2007, Tied 10th 2008.
2010-2011 Modified FWD RallyCross (Points Champion) http://www.sccahawaii.org/pics2008/s.../img_38944.jpg
Everything is complex if taken to such elaborate description. Imagine writing out every action of the human body when we do something as simple as blinking our eyes, or even a snowflake melting on the windshield of a Mini. Nevertheless, that is a pretty mindboggling description demonstrating these ain't simple little machines. I will give mine some extra octane in appreciation of her effort.
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Those that can't, teach others how not to.
Makes me long for the days of my 1965 Ford Mustang Convertible with a 289 2V carb. What you see is what you get! Wanna improve performance? Adjust the dwell and the timing. Wanna improve gas mileage? Do the same in the opposite direction. No black magic there, lads! That being said, my MCS is a far greater joy to drive! Thanks for the rundown. It is an amazing list, indeed!
