Note 1. Below are the norms for the content of harmful impurities in the exhaust gases of cars with gasoline engines. operating in Russia at the time of writing this guide. The norms are regulated by GOST R 52033-2003, introduced on 01/01/2004 to replace the previously valid GOST 17.8.3.03-87.
Note 2. GOST uses the following terminology: A two-component exhaust gas aftertreatment system is a system that reduces the content in exhaust gases, mainly carbon monoxide and hydrocarbons, without feedback on the composition of the working mixture. Three-way exhaust gas aftertreatment system - feedback system (according to excess air ratio X), providing a reduction in the content of carbon monoxide, hydrocarbons and nitrogen oxides in the exhaust gases.
Carbon monoxide content (SO) and hydrocarbons (NS) in the exhaust gases of cars is determined when the engine is idling for two crankshaft speeds set by the manufacturer for this model: minimum (nmin) and increased (npov).
If there is no such data, then the check is performed under the following conditions: The value of nmin must not exceed 1100 min-1;
The value of n is set within:
- 2500-3500 min-1 for vehicles not equipped with an exhaust gas aftertreatment system;
- 2000-3500 min-1, for vehicles equipped with an aftertreatment system.
To perform this work, you will need an exhaust gas analyzer with a relative error of no more than 6%:
- for models not equipped with neutralization systems or equipped with two-component (oxidative) neutralization systems - a two-channel gas analyzer designed to measure the content of carbon monoxide (SO) and hydrocarbons (CH);
- for models equipped with three-component neutralization systems - four-channel gas analyzers designed to measure the content of CO, CH, carbon dioxide (CO2) and oxygen (About2).
Quadruple gas analyzers can also be used to perform measurements on vehicles not equipped with neutralization systems or equipped with two-way neutralization systems. If you do not have such a device and there is no way to borrow it for a while, then almost any auto repair shop will do this job for you for a moderate fee.
Before starting measurements, by an external inspection, check the presence of systems and devices on the vehicle that reduce harmful emissions. If the actual equipment of the car does not correspond to the one set by the manufacturer, it makes no sense to carry out measurements - you will not pass the technical inspection.
Before measurement, the car engine must be warmed up to a temperature not lower than the operating temperature of the engine oil or coolant specified in the vehicle operating instructions, but not lower than 60°C. After warming up the engine, the car should be prepared for measurements in the following order:
- install gear lever (or mode selector for vehicles with automatic transmission) to a neutral position;
- apply the parking brake and turn off the engine;
- connect tachometer and oil temperature gauges (if it is included in the set of measuring equipment);
- insert the sampling probe of the gas analyzer into the exhaust pipe of the car to a depth of at least 300 mm from the cut (with an oblique cut of the exhaust pipe, the depth is measured from the short edge of the cut).
On models not equipped with an aftertreatment system, measure in the following order:
- before taking measurements, check and set zero readings of the gas analyzer on the CO and HC measurement scales;
- start the engine by pressing the throttle control pedal, increase the engine speed to n and operate in this mode for at least 15 seconds;
- release the accelerator pedal, set the minimum engine speed nmin not earlier than after 30 seconds, measure the content of carbon monoxide CO and hydrocarbons HC;
- set the increased engine speed nturn and measure the content of CO and HC not earlier than after 30 s.
On vehicles equipped with an aftertreatment system, measure in the following order:
- before starting measurements, check and set zero readings of the gas analyzer on the scales for measuring CO, HC and CO2.
- take measurements in the following order:
- start the engine by pressing the throttle control pedal, increase the engine shaft speed to nst, maintain this mode for 2...3 min (at ambient temperature below 0°C - 4...5 min), and after stabilization of the readings, measure the content of CO, HC, and also fix the value of the coefficient of excess air
- set the minimum engine speed to nmin and measure the content of carbon monoxide and hydrocarbons not earlier than 30 s later. Measurement should be started no later than 30 s after checking in the npts mode.
On vehicles equipped with a three-component exhaust gas aftertreatment system and an integrated diagnostic system, before measuring the CO and HC content, the engine and the neutralization system are checked for operability according to the diagnostic indicator located on the dashboard:
- when the ignition is turned on, before starting the engine, the diagnostic indicator should turn on for a short period of time; if there is no corresponding signal of the diagnostic indicator after the ignition is turned on, the further verification procedure is stopped
- after starting the engine, the diagnostic indicator should turn off; if the diagnostic indicator remains on while the engine is running, the further verification procedure is stopped.
The content of CO and HC in the exhaust gases
The content of CO and HC must be within the limits of the data established by the vehicle manufacturer, but not more than:
The value of the coefficient of excess air λ in idling mode for ncold for cars. equipped with a three-way neutralization system must be within the data set by the manufacturer. In the absence of such data, λ should be between 0.97 and 1.03.