Checking and adjusting idle speed and mixture quality (Escort 5)

HCS and CVH engines

Many of the engines are equipped with fuel injection systems of one kind or another, which are completely controlled by the engine management system. On most of these vehicles, there is no provision for idle speed or mixture control without special equipment.

On carburettor engines and 1.6L EFI engines with fuel injection, inspection and adjustment are required as part of the maintenance requirements and are described below.

Idle speed and mixture quality, checking and adjustment - engines with carburetor

Before performing checks and adjustments, check that the spark plugs are in good condition and have the correct interelectrode gap. An accurate tachometer and exhaust gas analyzer are required for adjustments.

Make sure all electrical consumers are turned off during the following procedures.

Connect the tachometer to the engine according to the manufacturer's instructions and insert the exhaust gas analyzer probe into the exhaust pipe.

Warm up the engine to normal operating temperature until the radiator fan turns on. Remove the connector from the fan temperature sensor and short-circuit the connector contacts with a jumper to turn on the radiator fan in constant operation mode (see Fig. 1.11).



If present, remove the vacuum line from the throttle body.



Start the engine and increase the engine speed to 3000 rpm for 30 seconds, and repeat this after three minutes during the checking/adjusting procedure.

With the throttle fully released, check the idle speed after 3-5 seconds. If adjustment is necessary, turn the idle speed screw until the required speed is obtained.

To adjust the mixture quality, to access the adjusting screw, you need to remove the plug from the screw using a thin screwdriver. To do this, remove the air filter, while the crankcase ventilation hose should remain in place.

Turning the mixture quality adjusting screw clockwise results in a leaner mixture, and conversely, turning the screw counterclockwise results in a richer mixture (see Fig. 1.12).

Checking and adjusting idle speed and mixture quality - 1.6 liter EFI engines

Run the engine at high idle speed until the engine reaches normal operating temperature and the cooling fan turns on. Check the CO content in the exhaust gases and compare the result with the required value. To adjust the mixture quality, remove the plug from the adjusting screw and make the adjustment (see Fig. 1.13).





Check the idle speed by disconnecting the multi-pin plug from the idle speed control valve. Increase the engine speed to 2000 rpm and hold the engine at this speed for 30 seconds, fully release the throttle and check the idle speed.

To adjust, remove the plug with a small screwdriver and, by turning the adjusting screw, set the required idle speed. Turning the screw counterclockwise increases the idle speed (see Fig. 1.14).



Reconnect the idle speed control valve multi-pin plug and check that the engine speed briefly increases to 900 rpm, then decreases to the specified normal idle speed.

The original version can be found on the website (FordBook.ru)