Verification conditions
The engine is warmed up to normal operating temperature.
An air filter is installed in the engine intake system.
All hoses and pipelines of the intake system are connected to the appropriate fittings.
All accessories (air conditioning, consumers of electrical energy) off.
All vacuum lines (hoses and pipelines) connected to the appropriate fittings.
All electrical connectors of the fuel injection system are connected.
The initial ignition timing must be correctly adjusted.
The automatic transmission control lever is in the neutral position.
An additional tachometer for measuring the engine speed and a device for measuring the concentration of CO / CH in the exhaust gases must be calibrated in accordance with the instructions for use of these devices.
Examination
Start the engine.
Increase the engine speed to 2500 min-1 and let the engine run in this mode for about three minutes.
Leave the engine to idle.
Insert the probe of the CO/CH exhaust gas measuring instrument into the exhaust pipe to a depth of at least 40 cm.
Check the reading of the CO/CH exhaust gas meter immediately with the engine idling and/or at 2500 rpm-1.
Note. When measuring the concentration of CO / CH in the exhaust gases at an increased engine speed, the engine speed value must comply with the requirements of the legislation of the country where the vehicle is operated, and may differ from the value given in the description of the test procedure (2500 min-1).
If the concentration of CO/CH in the exhaust gases of the engine does not meet the legal requirements for the toxicity of exhaust gases, then it is necessary to find out the cause of this discrepancy and eliminate it. The procedure for searching for the cause of the increased content of CO / CH in the exhaust gases is given below.
With a normal content of CO in the exhaust gases and an increased content of CH (engine idling may also be rough) do the checks below (Checks must be done in the order in which they are listed):
- check engine ignition system (the correct setting of the ignition timing, the condition of the spark plugs: performance, the gap between the electrodes);
- check the gaps in the valve drive mechanism;
- check for leaks (closed) through intake and exhaust valves;
- check the condition of the cylinder-piston group of the engine.
With a low content of CO in the exhaust gases and an increased content of CH (there may also be uneven engine idling and instability of the instrument readings when measuring CH) do the checks below (Checks must be done in the order in which they are listed):
- check the absence of air leakage in the intake system - in the crankcase ventilation system, in the intake manifold connections, in the receiver connections, in the throttle valve connections, through the idle speed controller;
- check the absence of air leakage through the leaky connections of the vacuum brake booster hoses;
- check the fuel injection system (when the engine is running on a lean air-fuel mixture, misfiring is possible (with a good ignition system), which leads to an increase in the concentration of unburned hydrocarbons in the exhaust gases (CH)).
With an increased content of CO in the exhaust gases and an increased content of CH (Rough idling and black smoke from the exhaust may also be observed) do the checks below (Checks must be done in the order in which they are listed):
- check the condition of the engine air filter;
- check the serviceability of the idle speed regulator;
- check the health of the system of fuel injection elements: fuel pressure regulator, coolant temperature sensor, electronic control unit of the fuel injection system, fuel injectors, throttle position sensor, air flow sensor.