Cars with a catalytic converter (Opel Vectra A)

Depending on the variant, Opel Vectra/Calibra vehicles may have a catalytic converter; in this case, the engine must run only on unleaded gasoline. Cars with a regulated catalytic converter are also equipped with a mixture control system. The basis of such a system can be either a carburetor or a fuel injection system that regulates the air/fuel ratio depending on the engine operating mode and the oxygen content in the exhaust gases. Conventional carburetor (for example, 2E3) does not provide such an opportunity, since it does not have a corresponding control unit. Either an electronically controlled carburetor or a fuel injection system equipped with a computer is used.

The computer receives signals from the lambda probe, which is installed on the intake pipe or exhaust manifold of the engine and is constantly blown by the flow of exhaust gases. The lambda probe produces a voltage whose value is proportional to the residual oxygen content in the exhaust gases, and the computer, in accordance with this value, regulates the air/fuel ratio in the combustible mixture. This is necessary for two reasons: firstly, the engine operating mode is constantly changing (idle, full throttle, etc.); secondly, afterburning, which occurs in the catalyst, is possible only with a certain amount of fuel in the exhaust gases.

Afterburning, which occurs in the catalytic converter at temperatures from 300°C to 800°C, requires a higher fuel content in the combustible mixture than during normal combustion. Therefore, in cars with a catalytic converter, fuel consumption increases by approximately 5%.



The catalyst is installed instead of an additional muffler. It is a monolithic honeycomb structure coated with platinum and rhodium. An elastic and heat-resistant wire mesh is used to attach the impact-sensitive ceramic catalyst body.

The Opel Vectra/Calibra uses a three-way catalytic converter. This means that it controls three chemical reactions simultaneously: the oxidation of carbon monoxide (CO) and hydrocarbons (HC), as well as the reduction of nitrogen oxides (NO_x).

A catalytic converter is also installed on 1.7-liter turbodiesel engines. In this case, it is an unregulated oxidation catalyst that neutralizes carbon monoxide (CO) and hydrocarbons (HC), converting them into carbon dioxide (CO ₂) and water (H ₂ O).

Catalytic converter and exhaust gas recirculation

In the C16NZ and C18NZ engines, the nitrogen oxide content in the exhaust gases is reduced before the catalytic converter using the recirculation system. This system works as follows. The exhaust gas sampling valve installed on the engine intake manifold diverts some of the gases into the cylinders. The combustion temperature decreases, which means that the nitrogen oxide content in the exhaust gases also decreases. The recirculation system is switched off at temperatures below +20°C by a thermal switch installed in the vacuum pipeline. The system is maintenance-free.

Rules for using a catalyst

To avoid failures in the operation of the lambda probe and catalytic converter, the following requirements must be met.

(Text copied from a web portal: «www.opelbook.ru»)

Petrol engines

• Use only unleaded petrol.
• When equipping a vehicle with a catalytic converter, before installing it, fill the tank with unleaded gasoline at least twice and run it out while driving.
• Do not push or tow the engine. Unburned fuel at the moment of ignition can cause the catalytic converter to overheat and fail.
• Avoid multiple cold engine starts. Unburned fuel accumulates in the catalytic converter and when the engine warms up, it burns explosively, causing damage to the catalytic converter.
• If you have difficulty starting the engine, do not keep the starter on for a long time. Find out the cause of the failure and fix it.
• Do not use chrome-nickel spark plugs, use only spark plugs with copper electrodes.
• If the ignition system fails, remove the fuel injection control relay or fuel pump relay until the cause is determined.
• Do not check for spark with the spark plugs disconnected.
• Do not check engine operation by disconnecting the high-voltage wire from one of the cylinders.
• If the ignition is not working properly, reduce the speed and correct the problem.
• When adding engine oil, never exceed the maximum level mark: excess oil, as a result of incomplete combustion, will get into the catalytic converter and may damage or completely disable it.

Petrol and diesel engines

• Do not leave the car on dry leaves or in the grass. The catalytic converter has a very high temperature, which can lead to a fire.
• When adding engine oil, never exceed the maximum level mark: excess oil, as a result of incomplete combustion, will get into the catalytic converter and may damage or completely disable it.