Quantity setting device and control path generator: Function (Articles)

Why TDI tuning is hardly possible through modifications to the fuel injection pump - a brief explanation using the 97 AFN as an example .

In the 90 and 110 horsepower TDIs and other electronically controlled direct injection engines equipped with the VP 37 injection pump, the quantity control unit and the control slide position sensor (which senses the instantaneous position of the control slide) are the core components of the EDC (Electronic Diesel Control) system, and are located within the injection pump.
The solenoid (MSW) is a relatively simple electromagnet that is driven by the MSG with pulsed DC voltage and, against a spring force, moves the control slide.

The track circuit (RWG) consists of two coils: a reference coil and a measuring coil. The inductance of each coil is determined by a short-circuit ring. The reference ring is fixed, while the measuring ring is moved by the signaling system. During operation, the track circuit measures both inductances using an alternating voltage signal of approximately 10 kHz. From the relationship between the input and output, an evaluation circuit generates a measurement voltage, the value of which is a measure of the displacement of the actuator.

Two coils are required in the pump because the inductance changes significantly with temperature. By relatively evaluating two coils in the same warm environment, temperature-related errors can be compensated for.
If these components no longer meet their specified values, the entire engine performance can become erratic, emissions levels can be exceeded, and/or power output can decrease.

Therefore, a monitoring function for the pump has been integrated into the EDC. Every time the ignition is turned on, the throttle pedal is moved from the idle position to the full throttle position. In various positions, the relationship between the control voltage of the interlocking system and the signal from the setpoint generator, as well as the sensor voltage at the lower and upper limits, is analyzed and compared with a target range.
If the analysis result falls outside the very narrow tolerance range, an error is logged, and the glow plug check indicator will flash, long before more serious malfunctions such as a significantly excessive exhaust gas recirculation rate or excessive soot buildup occur.

This is the initial check, which will not be repeated in this level of detail until the next engine start. With the engine running, there is more room for adjustments to the control signal generator to increase the injection volume and thus the power output via a power box, "10-cent tuning," or similar methods.

The initial check requires that in pump manufacturing, the alignment between the MSW (motor shaft) and the RWG (rotor water gland) is performed very precisely, specifically within the aforementioned tolerance range. To achieve this, the reference short-circuit ring and the measurement short-circuit ring, which is attached to the switch axis of the HDK sensor, are adjusted with a precision in the range of 1/10 mm.

In addition, this ensures that private attempts, for example, to increase the injection amount by modifying the actuator setting, often result in a constantly blinking glow plug indicator, which means that inexperienced hobby tuners often can no longer find a setting without blinking, and Bosch can send out nice invoices for readjustments.

However, the initial check does not verify the (factory-calibrated, and also very precisely adjusted) position of the MSW and RWG on the pump housing. Therefore, by shifting the upper part of the pump, the injection quantity can be subtly altered across the entire range from idle to full load for the EDC system.
The adjustment range is so wide that, in extreme cases, the car may barely start, and its top speed may not even reach 100 km/h, or the engine may already be revving to dizzying heights of 4000 rpm or more in idle.

If one attempts to extract more power by increasing the injection quantity (which requires very small adjustments, on the order of 0.1 mm, of the pump's upper section towards the injection lines), the behavior in the transition range from idle to low load quickly becomes erratic – the car initially jerks when lightly accelerating at speeds below approximately 1300 rpm in higher gears. With further adjustments to the MSW (presumably a vehicle modification), the tendency for the vehicle to jerk and lurch becomes increasingly pronounced, to the point where it becomes practically undrivable, even before a common performance increase achieved through tuning is reached.

Das MSW als Ursache von Motorlaufproblemen

Since the fuel injection control system must operate with high precision to avoid jerking, even when the throttle position is correct, any radial play or stiffness in the MSW (mechanical swivel valve) shaft is detrimental to the engine's running smoothness.

Bei Verdacht auf solche pumpenseitige Ursachen von Motorlaufproblemen kann schon eine Handprobe brauchbare Anhalte liefern.
First, remove the pump cover.
If a tool for the 3-point screw is not available, you can file down a "too small" socket to fit, or, for example, use a mini cutting disc to mill a slot in the head of the screw for a screwdriver to engage.

When removing the cover, diesel will leak out, unless approximately 50 - 100 ml has previously been slowly pushed back out of the pump through the return line using compressed air (e.g., a syringe) .

Zur Prüfung des MSW den Meßring vom oben gezeigten Anschlag wegschwenken und auf das Gefühl bei der Bewegung achten. Er sollte sich feinfühlig (gegen eine mäßige Rückstell-Federkraft) bis zum anderen Ende der gebogenen Magnetbleche bewegen lassen und dort gegen einen exakt definierten, festen Anschlag (ebenso wie der Nullanschlag) laufen.
A slight amount of longitudinal play in the wave (up to approximately 1 mm) is not critical, as long as the measuring ring does not rub against the magnetic laminations (the laminations can be slightly bent if necessary).

Verschleißbedingtes Spiel z.B. zwischen Exzenter der MSW-Welle und dem Regelschieber kann so leider kaum festgestellt werden, aber durchaus zu Ruckelproblemen usw. führen.
Seitliches Spiel und jegliches Klemmen oder Hakeln der Welle können ebenfalls zu unsauberem Motorlauf, Ruckeln, evtl. Leistungsverlust und auch Fehlereinträgen führen.
In diesem Fall kann die Pumpe meist als verbraucht bzw. verschlissen angesehen werden, und eine intakte Austauschpumpe wird in aller Regel die Laufprobleme lösen.

If the MSW (presumably a type of engine) is simply experiencing difficulty starting, a cleaning additive in the diesel fuel might help, with a bit of luck.

Verläßlichere Prüfungen können Bosch-Dienste durchführen (Hysterese). While this typically involves costs, they can be a worthwhile investment when considering the significantly larger expense of replacing or installing a new pump.

Quantity setting device and control path generator: Function
ulf 10-06-2003, 21:55
Why TDI tuning is hardly possible through modifications to the fuel injection pump - a brief explanation using the 97 AFN as an example . In the 90 and 110 horsepower TDIs and other electronically controlled direct injection engines equipped with the VP 37 injection pump, the quantity control unit and the control slide position sensor (which senses the instantaneous position of the control slide) are the core components of the EDC (Electronic Diesel Control) system, and are located within the injection pump. The solenoid (MSW) is a relatively simple electromagnet that is driven by the MSG with pulsed DC voltage and, against a spring force, moves the control slide. The track circuit (RWG) consists of two coils: a reference coil and a measuring coil. The inductance of each coil is determined by a short-circuit ring. The reference ring is fixed, while the measuring ring is moved by the signaling system. During operation, the track circuit measures both inductances using an alternating voltage signal of approximately 10 kHz. From the relationship between the input and output, an evaluation circuit generates a measurement voltage, the value of which is a measure of the displacement of the actuator. Two coils are required in the pump because the inductance changes significantly with temperature. By relatively evaluating two coils in the same warm environment, temperature-related errors can be compensated for. If these components no longer meet their specified values, the entire engine performance can become erratic, emissions levels can be exceeded, and/or power output can decrease. Therefore, a monitoring function for the pump has been integrated into the EDC. Every time the ignition is turned on, the throttle pedal is moved from the idle position to the full throttle position. In various positions, the relationship between the control voltage of the interlocking system and the signal from the setpoint generator, as well as the sensor voltage at the lower and upper limits, is analyzed and compared with a target range. If the analysis result falls outside the very narrow tolerance range, an error is logged, and the glow plug check indicator will flash, long before more serious malfunctions such as a significantly excessive exhaust gas recirculation rate or excessive soot buildup occur. This is the initial check, which will not be repeated in this level of detail until the next engine start. With the engine running, there is more room for adjustments to the control signal generator to increase the injection volume and thus the power output via a power box, "10-cent tuning," or similar methods. The initial check requires that in pump manufacturing, the alignment between the MSW (motor shaft) and the RWG (rotor water gland) is performed very precisely, specifically within the aforementioned tolerance range. To achieve this, the reference short-circuit ring and the measurement short-circuit ring, which is attached to the switch axis of the HDK sensor, are adjusted with a precision in the range of 1/10 mm. In addition, this ensures that private attempts, for example, to increase the injection amount by modifying the actuator setting, often result in a constantly blinking glow plug indicator, which means that inexperienced hobby tuners often can no longer find a setting without blinking, and Bosch can send out nice invoices for readjustments. However, the initial check does not verify the (factory-calibrated, and also very precisely adjusted) position of the MSW and RWG on the pump housing. Therefore, by shifting the upper part of the pump, the injection quantity can be subtly altered across the entire range from idle to full load for the EDC system. The adjustment range is so wide that, in extreme cases, the car may barely start, and its top speed may not even reach 100 km/h, or the engine may already be revving to dizzying heights of 4000 rpm or more in idle. If one attempts to extract more power by increasing the injection quantity (which requires very small adjustments, on the order of 0.1 mm, of the pump's upper section towards the injection lines), the behavior in the transition range from idle to low load quickly becomes erratic – the car initially jerks when lightly accelerating at speeds below approximately 1300 rpm in higher gears. With further adjustments to the MSW (presumably a vehicle modification), the tendency for the vehicle to jerk and lurch becomes increasingly pronounced, to the point where it becomes practically undrivable, even before a common performance increase achieved through tuning is reached. Das MSW als Ursache von Motorlaufproblemen Since the fuel injection control system must operate with high precision to avoid jerking, even when the throttle position is correct, any radial play or stiffness in the MSW (mechanical swivel valve) shaft is detrimental to the engine's running smoothness. Bei Verdacht auf solche pumpenseitige Ursachen von Motorlaufproblemen kann schon eine Handprobe brauchbare Anhalte liefern. First, remove the pump cover. If a tool for the 3-point screw is not available, you can file down a "too small" socket to fit, or, for example, use a mini cutting disc to mill a slot in the head of the screw for a screwdriver to engage. When removing the cover, diesel will leak out, unless approximately 50 - 100 ml has previously been slowly pushed back out of the pump through the return line using compressed air (e.g., a syringe) . Zur Prüfung des MSW den Meßring vom oben gezeigten Anschlag wegschwenken und auf das Gefühl bei der Bewegung achten. Er sollte sich feinfühlig (gegen eine mäßige Rückstell-Federkraft) bis zum anderen Ende der gebogenen Magnetbleche bewegen lassen und dort gegen einen exakt definierten, festen Anschlag (ebenso wie der Nullanschlag) laufen. A slight amount of longitudinal play in the wave (up to approximately 1 mm) is not critical, as long as the measuring ring does not rub against the magnetic laminations (the laminations can be slightly bent if necessary). Verschleißbedingtes Spiel z.B. zwischen Exzenter der MSW-Welle und dem Regelschieber kann so leider kaum festgestellt werden, aber durchaus zu Ruckelproblemen usw. führen. Seitliches Spiel und jegliches Klemmen oder Hakeln der Welle können ebenfalls zu unsauberem Motorlauf, Ruckeln, evtl. Leistungsverlust und auch Fehlereinträgen führen. In diesem Fall kann die Pumpe meist als verbraucht bzw. verschlissen angesehen werden, und eine intakte Austauschpumpe wird in aller Regel die Laufprobleme lösen. If the MSW (presumably a type of engine) is simply experiencing difficulty starting, a cleaning additive in the diesel fuel might help, with a bit of luck. Verläßlichere Prüfungen können Bosch-Dienste durchführen (Hysterese). While this typically involves costs, they can be a worthwhile investment when considering the significantly larger expense of replacing or installing a new pump.

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