Various Tests

System pressure:
The system pressure is 2 bar and is adjustable. If the pressure is too low, and can not be adjusted, check by closing the return line if pressure rises (Defective on max. 3 bar, otherwise goes the pump). If so pressure regulator is faulty, if not, output of the pump and lines check (fuel filter).

To check the injectors, it makes sense to pull them out their seat, pressure cable remains connected. Can control the valves by leaving the plug on the valve to be tested, ignition switches and connects either to the circuit diagram pin 3-4-5-6 with 16 (only briefly touch better with series resistor !!). The valves have to give a clean beam and not drip after closing. Normally, these valves are actuated with only 3 volts, so be careful. Alternatively, let clamped in the removed state control unit, start engine.
(Assume vessel and only tap connection, not !! smoke)

Cold start valve and thermo-time switch:
In cooling water temperature below 35 °, the start valve must inject at startup for a brief moment. To check pull out the valve and hold it in a vessel. Lines remain connected. It is the same as the E-valve. Not injects it or is the temperature above 35 ° as its commitment to terminal W on Thermo time switch to ground. Injects it not still a startup, so the coil of the valve is resistive to measure (value of 4.2 ohm). For more troubleshooting with the wiring diagram. First, it is useful to find out what is missing, then to measure back to feeding.
Schematic as PDF

Trip contacts with the engine running:
On connector distributor voltmeter (analog) to pin 12 and 21 bzw.22 connect alternately. The value is 4 volts and the maximum deviation between two 0.4 volt. Engine speed 2000 rev / min. Alternatively Schliesswinkeltester.

Additional air slide:
He must be open when the engine is cold and closed when the engine is warm. At too low speed when engine is cold the ZLS is stuck in the closed state. When sawing in warm condition check, push through the hose to the intake pipe. If the engine then runs smoothly expand ZLS and replace if necessary.

Pressure cell:
The pressure capsule consists of two coils, and operates according to the principle of a transformer. The armature is connected to a diaphragm acting on the negative pressure. To the primary coil, a signal is transmitted and is based on a magnetic field. This is changed by the movement of the secondary coil and transmitted as a voltage signal to the control unit.

Setting throttle and throttle switch:
The stop screw out until DK is free. Then the screw until reindrehen until it rests on the DK, and then reindrehen quarter to half a turn. If the motor saws idle, turn the screw back minimal.
The screws on the DK switch solve and connect multimeter. Pin 14 and Pin 17eine resistance measurement to perform. The value must be approximately 0 ohms, if the Dk deflected to a degree so the display is OL. Each tick mark on the throttle body is 2 °. Set the throttle switch so that it opens at 1 °. Check again after setting, when deflected to a degree switch must be open. (It clicks into place.)

Idle and exhaust set:
The idle speed is adjusted to the screw on the return air duct. The idle speed is dependent on the manufacturer. The exhaust gas is set at the control device. This is usually in the interior (behind glove box).


Oldtimer-Steuergeräte - Peter Hemmersbach repariert defekte D-Jetronik Steuergeräte
Peter Hemmersbach repairs defective D-Jetronik control units in his workshop.
Oldtimer-Steuergeräte - alter Mercedes
The D-Jetronik injection was real "high-tech" in the late 60s and it took over the place of mechanically controlled injection systems in many top models.
Oldtimer-Steuergeräte - gepflegte Oldtimer sind auch heute zuverlässige Fahrzeuge
A classic car can even today be a very reliable vehicle. It is important to take good care of the technique and to have a little interest in the topic.


We repair D-jetronik control units
also lucas ecu´s, ignition control modules and fuel pump relays from your Vintage Car.


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