MB W124 300E -93 m103 don't start

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jarkko420sel
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Viestit: 58
Liittynyt: La 22.10.2005 10:06

MB W124 300E -93 m103 don't start

Viesti Kirjoittaja jarkko420sel »

Help needed ... motor don't start ... no ignition spark .... all component changed ... controlbox ... speedsensor .. ignitioncoill ... no spark even from directly fromignition coil .... OK control unit was used one and haven't test that really works but just to buy 2:nd ??? cost some money ???? ... speed senser seems to give some signal when tru to start ... ( multimeter/ohm) ... any new idea what and how to ignition system check ????
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JarkkoN
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Viestit: 4163
Liittynyt: Pe 01.09.2006 14:39
Paikkakunta: Tampere

Re: MB W124 300E -93 m103 don't start

Viesti Kirjoittaja JarkkoN »

Current flows from battery through the primary ignition coil to the ground, when the ignition key is turned on.
The current loads the coil's magnetic field with energy. This current is switched off and on periodically at each
time when a spark is needed. This is the primary side of ignition, it works with 12V and is controlled by the
control box. The exact timing of the switching is determined by the Hall-sensor which measures the crankshaft position.
Timing changes according to rpm and other conditions, this makes the system more complicated.

The secondary side of the ignition system is the high voltage side. The secondary coil is close to the primary coil and it
gets a high voltage pulse by means of induction each time when the primary coil current is switched off. This high voltage
gets to the distributor center and further to each spark plug through a rotating switch. The high voltage side is prone
to defects, such as small cracks in the distributor cap or condensed moisture causing short circuits.

First check that there is a primary current and that it's pulsed. Then check that your distributor cap and the
rotating switch are OK. The rotating switch has a piece of coal as a conductor, this could be broken.
It's a good idea to replace the old high voltage parts with new quality parts, if in doubt regarding the condition.
S211 E 320 CDI T 4matic 11/2006
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