Economic Driving (Economy)

Testing Readout For Economic Driving (Economy)

Operation

The indictor is connected to intake manifold by way of a vacuum line and indicates the momentary fuel consumption in dependence of intake manifold vacuum.

At high intake manifold vacuum the needle is in black field of readout (fuel consumption low) with decreasing intake manifold vacuum the needle will move into red field. The monetary fuel consumption increase.

On stopped engine the needle rests in red field against righthand stop pin.
Vacuum <= 0.08 bar.

Following start of engine the needle movies to the left and remains in range of black readout field depending on vacuum.
Needle against lefthand stop >= 0.585 bar.
Needle at beginning of red field approx. 0.4 bar.

Note:
If the needle stops at righthand stop in red field, a leak in vacuum line to indicator is indicated (connection point, line or the indicator is defective,

Renew vacuum line and/or indicator

If the readout is very slow, the cause may be oil in vacuum line and/or in indicator. A defective diaphragm of vacuum control unit on automatic transmission may result in oil flowing into vacuum system, which will then lead to a breakdown of indicator.

Testing

GPull off vacuum line (1) coming from intake manifold at distributor (3) and test vacuum at engine idle.
Nominal value: approx. 0.4 - 0.6 bar

If the nominal value is not attained, the vacuum line is contaminated or leaking. Clean vacuum line or renew.

If the nominal value it attained, connect vacuum lines (1 and 2) with each other, switch vacuum tester in-between. Run engine at idle. With vacuum <>0.585 bar, needle of indicator should be at lefthand stop, with vacuum approx. 0.4 bar at beginning of red field.

If so, a leak in vacuum system of light range regulation and/or air conditioning system is indicated.

Repair leaks.

If on vehicles with automatic transmission a vacuum control unit on transmission is detective, oil may also be present in indicator and its line. Clean line and renew indicator.