Control Pressure Regulator - Modification

NO: 81-05

December 22, 1981

Group: 25

5000/S, 5000 TURBO, 4000 (5 cyl.)

1981/1982 CIS cars only

Subject:
Control Pressure Regulator

Part Identifier 25 46

Key Points:
Modified to include an enrichment system

Begining with 1981 models, the control-pressure regulator is modified to include an enrichment system. Operation is as follows:

The modified control-pressure regulator is equipped with chambers I and II, which are separated by a diaphragm. When pressure in the two chambers is equal, the regulator performs as in the past and no additional enrichment occurs. When pressure is greater in chamber I than in chamber II, control pressure on the fuel distributor is reduced, enriching the mixture to the engine

Normally Aspirated Engines





When the engine is cold, the temperature switch is closed. Intake manifold pressure is the same at chambers I and II, because the one-way vacuum delay valve is completely open. On acceleration, however, pressure increases in chamber I more rapidly than in chamber II due to action of the delay valve. During this delay period, mixture enrichment occurs.

When the engine is warm, the temperature switch is open to atmospheric pressure. On acceleration, reduction in intake manifold vacuum never allows chamber I to be pressurized greater than chamber II. Thus, no enrichment can occur

Turbocharged Engines





When the engine is cold, the temperature switch is open. Thus, manifold pressure is applied to both chambers I and II of the control-pressure regulator. On acceleration, pressure increases instantaneously in chamber I but much more slowly in chamber II because of the restrictor in the hose. Until the pressures are equalized, mixture enrichment occurs.

When the engine is warm, the temperature switch is closed and cuts off chambers I and II from intake manifold pressure. Thus, no enrichment can take place

Specifications:

^ Temperature Switch

Normally aspirated engine
opens at 58°C +/- 3°
closes at 48°C +/- 3°

Turbo engine
opens at 48°C +/- 3°
closes at 58°C +/- 3°

^ Control Pressure Regulator
cold (20°C) 1.5 +/- 0.15 bar
warm 3.6 +/- 0.15 bar

At operating temperature and 380 mmHg vacuum applied to chamber II, and chamber I (upper chamber) vented to atmosphere (open)

1.6 +/- 0.15 bar