New Generation Motronic System (Adaptive)
A new generation of digital engine electronics with oxygen sensor control is applied to have the necessary control and regulation of the fuel/air mixture for production of the stoichiometric fuel/air mixture ration (14 kg air to 1 kg fuel)
Emission control is achieved through application of a three way catalytic converter, which oxidizes carbon monoxide (CO) and hydrocarbon composites (Hc) and reduces nitrogen oxide (NOx). These chemical reactions produce the non-poisonous exhaust gas components carbon dioxide (C02), H20 and nitrogen (N2).
A so-called self-learning system for fuel/air mixing and emission control is integrated in the new generation of digital engine electronics for the first time. This new technology makes it possible to correct deviations from the nominal value for injection time.
Idle speed regulations integrated in the control unit for digital engine electronics. Sensors, such as speed sensor and temperature sensor for the engine, and switches for idle speed and air conditioner are processed in the control unit. The correct amount of air, witch is required for the nominal engine speeds in each and every operating condition, is supplied to the engine via an electrically operated valve on the basis of values calculated in the control unit.
A more homogeneous "exhaust mixture" is placed at disposal of the oxygen sensor control by installing the sensor in the inlet opening of the catalytic converter. This installed position "far away from the engine" considerably reduces the peak thermic loads of the sensor to such an extent, that the sensor only has to be replaced after 50,000 miles / 80,000 km.
The self-learning system or adaptive pilot control of digital engine electronics mentioned above is based on continuous comparison of data, which are compared with the evaluated oxygen values of the sensor in a permanently programmed pilot control graph and constantly keep the memory up to date. The factory, by which the oxygen sensor control, must correct the pilot control value, is stored in an intermediate memory. This factor goes immediately in the fuel injection time and extends or shortens this time accordingly. Consequently oxygen sensor control keeps the so-called error adaption time (e.g. the time required by a sensor to detect and correct an erroneous mixture) to a minimum.
1 = PI control (proportional/ integral)
2 = Signal filter
3 = Memory (large signal)
4 = Comparison
5 = Memory (small signal)
6 = Oxygen sensor signal
7 = Comparison
8 = Engine
9 = Oxygen sensor
Small deviations, such as leakage in engine intake system (leaking oil filler neck cap or oil dipstick, loose hose clamps on dust cover) are corrected with the adaptive pilot control, so that neither pickup behavior impairment nor poor emission control will occur. The ability of digital engine electronics to carry out corrections has also made the barometer box for altitude correction superfluous, since the adaptive pilot control will, for example, recognize the "thin" air on a high mountain pass (same volume, but less mass) as an excessively "rich mixture" and shorten the fuel injection time accordingly.
In order to keep the data stored the memory always has electric power, for example after starting, and remains in the mA range. The adaption and storing of comparison values take place within several minutes, should the source of power be interrupted. The intermediate memory is always supplied with 12 volts and doesn't lose its up-to-date correction value even after stopping the engine, so that when restarting the engine it is not necessary to have new adaption.
If the source of power for the memory is interrupted (e.g. replacement of battery), new adaptation takes place while running engine in only several minutes. Discharging the battery is not possible, since the memory only requires low mA.
The adaptive pilot control can be switched off for checking and/or troubleshooting (e.g. defective fuel injector, wrong intake air, etc.). This is accomplished by connecting pin 30 of the digital engine electronics control unit with car ground. As long as this connection is made the memory takes on factor 1 and the oxygen sensor control remains in operation but without influence. Troubleshooting and checking procedures are the same as for all other oxygen sensor controlled engines.
This engine is based on the 3.5 liter ECE engine. The compression ratio was reduced to 8.0:1 by using bowl-in pistons, so that leadless gasoline can be used. This and emission control measures of USA legislation have led to an engine power output of 136 kW.
The factory recommends the following test for the adaptive system on 3.5 liter:
1. Check that CO is 0.2 - 1.0%
2. Pull secondary vent hose, on the primary crankcase vent hose, off and plug it.
3. CO goes down and then back up to original value.
4. After 40 seconds disconnect oxygen sensor and refit secondary hose.
5. CO goes up and stays up.
6. Reconnect oxygen sensor.
7. CO goes back to original value.
METHOD FOR CHECKING RPM AND REFERENCE SENSOR OF THE MOTRONIC SYSTEM USING THE BMW SERVICE TEST- 2013
Physical Check
Check RPM and reference sensors for tight fit, damage and electrical contact of plug/socket connections.
Check that plug/socket connections are not mixed up (reference socket is grey and plug has grey band) (RPM socket is black and plug is without band)
Check RPM and reference sensors for correct installation:
(0.7 to 1.0 mm clearance between sensor and ring gear teeth flywheel block; sensor in wrong location?)
Vehicle Preparation
Install motronic adaptor to motronic control unit harness plug.
Tester Operation
Switch on machine - tester proceeds with self test & calibration Press acknowledge (????) when calibration is complete
Press multimeter (M)
Press scope self trigger. (#22)
Press frequency out (#13) then 100 (for 100Hz, oscilloscope triggering)
Press acknowledge (????) twice
Tester Cable Connections
Two separate cables are required - Universal Harness and Frequency out cable. Cables plug in boom sockets #2 (freq.out) and #4 (BMW diagnostic cable/Universal harness) connect Universal Harness, KL L (black clip) to freq. out positive (Blue clip)
NOTE: There will not be a pattern showing on the tester oscilloscope
Terminal Connections For Checking Reference Sensor
- Connect Universal Harness, D + (blue clip) to terminal #25 (reference positive terminal).
- Connect Frequency out negative (-) to terminal #26 (reference negative terminal).