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Engine Management Systems
 
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Pelican Technical Article:

Engine Management Systems

Nick Czerula

Time:

1 hour1 hr

Tab:

$0 to $350

Talent:

****

Tools:

ECM flash tool, supplied with software

Applicable Models:

BMW Z3 (1996-02)

Parts Required:

DME flash tool and software

Hot Tip:

Use this info to better understand your BMW Z3 engine

Performance Gain:

Fuel economy and performance

Complementary Modification:

Upgrade DME software

Z3 engine management systems--an overview:

BMW Z3 sports cars (1996 - 2002) are equipped with digital engine management systems (called Digital Motor Electronics or DME). The engine control module (ECM) in these systems is programmed with software for control of fuel injection, ignition and other functions. BMW DME systems comply with second generation on-board diagnostics (OBD II) standards.

The table below summarizes the DME systems used in Z3 sports cars:

 Model, Years Engine DME System
 Z3 Roadster 1.9, 1996-1998 M44 B19 (4 cylinder) Bosch DME M5.2
 Z3 Roadster 2.3, 1999-2000 M52 TU B25 (6 cylinder) Siemens MS 42.1
 Z3Roadster 2.5i, 2001-2002 M54 B25 (6 cylinder) Siemens MS 43.0
 Z3 Roadster/Coupe 2.8, 1997-1998 M52 B28 (6 cylinder) Siemens 41.1
 Z3 Roadster/Coupe 2.8, 1999-2000 M52 TU B28 (6 cylinder) Siemens 42.1
 Z3 Roadster/Coupe 3.0i, 2001-2002 M54 B30 (6 cylinder) Siemens MS 43.0
 M Roadster/Coupe, 1998-2000 S52 B32 (6 cylinder) Siemens MS 41.1
 M Roadster/Coupe, 2001-2002 S54 B32 (6 cylinder) Siemens MS S54

 Engine control module (ECM):
The engine control module (ECM) is mounted in the electronics-box (E-box) at right rear of the engine compartment (green arrow).
Figure 1

The engine control module (ECM) is mounted in the electronics-box (E-box) at right rear of the engine compartment (green arrow). In MS 42.1 and MS 43.0 cars the ECM is flash-programmable to boost certain performance parameters, such as allowing for higher top RPM or increasing low-end torque. In this photo, the E-box lid has been removed. There are three Phillips head screws you have to loosen to remove the cover. When the cover is removed, the screws remain with the lid. Also, check that the cover seal is intact and in good shape. 

Fuel supply, fuel injection

An electrically operated fuel pump, located inside the fuel tank, supplies high pressure fuel [approx. 3 - 5 bar (44 - 73 psi) depending on engine] to the engine fuel rail. The fuel rail in turn distributes fuel to the electronically actuated fuel injectors.

The ECM meters the fuel output of injectors using pulse width signals. It varies the pulse width based on input signals. Inputs to the ECM include:
  • Air intake volume using mass airflow sensor signal.
  • Ambient and coolant temperature signals.
  • Accelerator pedal signal.
  • Crankshaft and camshaft position signals.
  • Knock sensor signals

Intake system - The M44 4-cylinder engine uses a dual resonance intake system (DISA) which effectively provides the advantages of short and long intake runners within the same engine.
Figure 2

Intake system - The M44 4-cylinder engine uses a dual resonance intake system (DISA) which effectively provides the advantages of short and long intake runners within the same engine.

Intake system - Beginning with the 1999 Z3 Roadster 2.
Figure 3

Intake system - Beginning with the 1999 Z3 Roadster 2.3, the M52 TU or M54 intake manifold is known as the resonance / turbulence intake system. The molded plastic intake manifold consists of two sets of three intake runners. Resonance valves are used to vary the length of the runners in order to enhance low end torque at low engine speeds or allow high volume air flow at medium or high engine speeds.


The intake manifold is also equipped with a 5.5 mm turbulence port for each cylinder. These ports channel idle and low speed air from the idle speed control regulator to one intake valve in each cylinder. (There are 2 intake valves per cylinder.) Air rushing through one valve causes air swirl and more efficient fuel atomization in the cylinder.

In the 2001 - 2002 M Roadster and Coupe with S54 engine, six individual throttle housings are used. Positioned much nearer the cylinder than a single throttle housing can be, the six throttles bring atmospheric pressure practically to each cylinder, reducing lag time in the airflow. Thus the engine can react much more quickly to throttle movement.

Variable camshaft timing (VANOS) - Z3 and M cars with 6-cylinder engine are equipped with ECM-controlled variable camshaft timing or VANOS.
Figure 4

Variable camshaft timing (VANOS) - Z3 and M cars with 6-cylinder engine are equipped with ECM-controlled variable camshaft timing or VANOS. 

The system uses engine oil pressure to adjust camshaft timing, offering the following advantages:
  • Increased power.
  • Higher low end and medium speed torque.
  • Improved idle and fuel efficiency.
  • Elimination of external EGR plumbing (internal EGR).
  • Quicker warm-up and lower emissions.

Three variants of the VANOS system are used:
  • Single VANOS adjusts intake valve timing only in 1997 - 1998 M52 and 1998 - 2000 S52 engines. 
  • Double VANOS operates independently on both intake and exhaust valve timing in 1999 - 2002 M52 TU and M54 engines.
  • High pressure double VANOS operates independently on both intake and exhaust valve timing in 2001 - 2002 S54 B32 engine.

Throttle control, idle control - 4-cylinder models and 6-cylinder models with DME MS 41.
Figure 5

Throttle control, idle control - 4-cylinder models and 6-cylinder models with DME MS 41.1 are equipped with a conventional throttle assembly with an accelerator cable. In MS 42.1 vehicles, an accelerator cable connects the gas pedal to an electronic throttle valve.

In MS 43.
Figure 6

In MS 43.0 vehicles, the throttle cable is eliminated and throttle actuation is completely electronic (drive-by-wire). In the S54 engine with 6 individual throttles, an ECM controlled servo motor drives the throttle operating shaft through a tiny gearbox. All six throttles operate from a single shaft.

The idle speed control valve, located under the intake manifold, is controlled by the ECM to bypass varying amounts of air around the closed throttle valve.
Figure 7

The idle speed control valve, located under the intake manifold, is controlled by the ECM to bypass varying amounts of air around the closed throttle valve. Idle speed is not adjustable.

Ignition and knock control - The ignition system uses one ignition coil per cylinder, each coil mounted above a spark plug.
Figure 8

Ignition and knock control - The ignition system uses one ignition coil per cylinder, each coil mounted above a spark plug. Multiple sparks per ignition cycle are used to reduce emissions and extend spark plug life. Spark timing is controlled by the ECM using an ignition spark "map". Spark timing is not adjustable. 


However, to prevent engine damage in case of adverse conditions or poor fuel quality, knock (detonation) sensors are mounted on the engine crankcase. These are microphones tuned to the frequency of engine knock and communicate such knock to the ECM. The ECM can respond to these signals by changing (usually retarding) ignition timing at one or more cylinders. (6-cylinder engine shown in photo) 

Exhaust manifolds and oxygen sensors

The 4-cylinder model is equipped with a conventional exhaust manifold. As required by the OBD II standard, two oxygen sensors are installed, one ahead and another behind the catalytic converter in the middle exhaust pipe.

The M52 engine (1997 - 1998) is equipped with two exhaust manifolds leading to a dual middle exhaust pipe. The pipe connects to the catalytic converter at a Y-junction and the two oxygen sensors are ahead and behind the catalyst.

In the 1999 - 2000 M version with S52 engine, a pair of pre-catalyst oxygen sensors are installed in the exhaust manifolds. A pair of post-catalyst oxygen sensors are in the pipes leading out of the dual catalytic converters.

In the M52 TU, M54 and S54 engines (1999 - 2002 Z3 model, 2001 - 2002 M Roadster and Coupe), the three front cylinders and three rear cylinders are each equipped with a separate exhaust manifold, each with an integrated catalytic converter. This allows the converters to heat up a very short time after a cold start. The manifolds are also equipped with 4 oxygen sensors, one before each catalyst and one after. Oxygen sensor signals are used by the ECM to control fuel delivery.
Re-flashing the engine control module (ECM)

We offer a well-tested system for re-flashing (reprogramming) the ECM, depending on your vehicle year and model:
The Shark Injector, designed for 1997 - 2002 models, re-flashes the ECM to improve low end torque.
Figure 9

The Shark Injector, designed for 1997 - 2002 models, re-flashes the ECM to improve low end torque. The car won't hesitate or lag, making it easier to drive. And with the extra torque you can drive in a higher gear and not have to downshift as often, thus improving fuel mileage. The Shark Injector may be upgraded via USB port, depending on your performance needs.

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Comments and Suggestions:
Dan Comments: Have a 01 z3 3.0 engine service engine light on code says lean fuel replaced spark plugs still on changed fuel filter still on code ereased sits afew days driven less than 3 miles will come back on it runs fine on every aspect just bugs me with the lite thing have any idea's would help greatly
June 30, 2016
  Followup from the Pelican Staff: Could be a vacuum leak or a faulty maf sensor. First step is to check the fuel trim data and see when the engine is lean. - Nick at Pelican Parts  
Benmcoupe Comments: Hi I have a z3 mcoupe 2001 with s54 engine. The elm light is on with loss of power also the abs light is on the brakes are in poor condition when plugged in the computer reveals a fault with abs sensor at the rear. Could this be related to elm being on? I had two of the coils changed Bosch ones as this was flagged up a few months ago, the car has only done about 20 miles since then and was running great but after sitting for six weeks has developed this fault, any advice would be appreciated cheers, Benjamin
February 9, 2016
  Followup from the Pelican Staff: It could be. to be sure, check the DME for fault codes. There will be one stored for the EML. - Nick at Pelican Parts  

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Page last updated: Mon 12/5/2016 02:07:20 AM