stalling at idle - engine dies

The problem is in the transition from the cold start system to the regular operating air fuel ratio. That intermediate step means running the still cold motor in a somewhat enriched state. Adequate fuel enrichment during warm up is missing. But let's first look elsewhere.

Has anyone checked the engine intake air warm up - after the air flow sensor and before the throttle some air is diverted to the cylinder head or exhaust manifold to be warmed up so the air fuel mixture can be leaner than it would be with cold air. If this "stove" isn't working as it should be the ECU, getting its engine temp signal from another sensor, will lean the mixture expecting the intake air to be warmed but it may not be warm at all so the air fuel ratio will then be too lean.

There may be a temperature sensor at the air flow sensor which is sending a false signal. (I don't KNOW if there is such a sensor on your motor, but it's worth a look.)

You've certainly invested a lot of money in this problem, hope these ideas help.

Hi thanks for the info but unfortunately this model of injection system (its very basic) has the airflow meter directly above the throttle butterfly , the airflow meter flap controls the fuel metering via an arm and plunger directly cconnected, there is no facility to take warm air from above the exhaust manifold like most cars.........so back to the drawing board....ha ha

How about the O2 sensor on the exhaust? This sensor is inactive until it heats up (about two or three minutes after cold starting). These sensors can send a false-positive in that they generate a signal, but it is the wrong signal at the wrong time.

Josh

When cold (oxygen sensor not yet warm, the engine control is operating in open loop mode, i.e. it will regulate the mixture according to various sensor inputs but without feedback from the oxygen sensor.

The basic mixture is adjusted by a sealed (plastic seal) adjustment screw, The screw is located next to the throttle body and is accessible through the long tube ("tower") from the top of the air filter enclosure. The screw is spring loaded and must be pushed down to be adjusted. It is factory preset to provide close to correct mixture without ECU control, and should normally never be adjusted afterwards. In fact this is how the non-electronic injection worked... the ECU with EHA (ElectroHydraulic Actuator is a later add-on from K-Jetronic to KE Jetronic (or CIS to CIS-E as Mercedes calls it). The mechanically adjusted mixture will then be fine adjusted by the EHA according to input from the ECU.

In your case, the mixture is obviously not correct in open loop mode, and this adjustment could be the suspect (maybe someone adjusted it?).

Another cause could be a vacuum leak, but that would also be the case in close loop mode when engine is warm, and it appears as if you already checked this.

A fault in the EHA could create similar symptoms (if it is somehow sticks near neutral position).

And another thing I can think of is the potentiometer, which gives the Air Mass Sensor position input to the ECU. But that would probably also give even worse problems when warm.