Exhausts System Service 03 9359-9499

At Frank Donnini  Repairs we offer Exhaust and Muffler Replacement for all Makes and models.

If you do hear any unusual noises coming from your exhaust then pop in to see us at 1/31 Onslow ave Campbellfield we will diagnose the fault and we can help you decide upon the very best course of action with minimal disruption and expense.

How does my exhaust system work?

It’s only when you hear or drive a car with a damaged silencer that you realise what a huge difference it makes to reducing noise levels.

And the way a silencer works is quite fascinating. It contains a deceptively simple set of tubes that are finely tuned to reflect the sound waves produced by an engine so that they cancel each other out.

If there is a hole in the silencer then the sound waves are no longer forced through the tubes and escape outside – increasing the noise level.

Other key components of your exhaust include exhaust pipes that are designed specifically for each car model and route exhaust fumes to the exit at the back of the car.

The exhaust manifold acts as a funnel. It collects exhaust gases from all cylinders of the engine then releases them through a single opening, often referred to as the front pipe.

The exhaust centre section works with the silencer to reduce noise and the tail pipe at the rear carries gases away from the vehicle. All of the components of an exhaust system are connected with a series of clamps, hangers, flanges and gaskets.


What Is A Catalytic Converter? 

Before the gases are expelled from the vehicle into the atmosphere, they may pass through a catalytic converter, which changes many harmful gases into less-polluting or harmful compounds.

The catalyst uses precious metals like platinum, rhodium and palladium set inside a housing to transform the harmful gases.

How Does the Oxygen Sensor Work?

An Oxygen sensor is installed in such a way that one of its surfaces is in contact with the exhaust gas flow and another surface with the outside air. Oxygen sensors do not measure the concentration of the oxygen gas in the exhaust gas, but measure the difference between the amount of oxygen in the exhaust and in outside air.

Based on the oxygen quantity in exhaust gases, voltage signals are provided constantly to the ECU so that it can maintain a stoichiometric air fuel ratio by regulating the fuel injection.

What are Upstream Oxygen Sensors and Downstream Oxygen Sensors?

The upstream oxygen sensor is located right before the catalytic converter. It is installed in the exhaust manifold or in the exhaust pipe near the engine. The role of the upstream oxygen sensor is to optimize the air-fuel ratio entering the engine. There can be one or two oxygen sensors depending on the number of cylinders.

Upstream monitors the oxygen gas in the exhaust gas and provides a signal to the ECU whether the mixture is weak or rich. When there is a high level of oxygen in the exhaust gas, ECU assumes that the air-fuel mixture is lean – so it adds more fuel to the engine. And when there is low oxygen in the in the exhaust, the ECU assumes that the air-fuel mixture is rich and it reduces the fuel supply accordingly.

The downstream oxygen sensor is located in the exhaust pipe after the catalytic converter. The role of the downstream oxygen sensor is to monitor the working and efficiency of the catalytic converter. There may be one or two oxygen sensors depending on the number of cylinders.

The ECU compares the signal from upstream and downstream sensors. If the catalytic convertor is working properly, the amount of oxygen after the catalytic converter should be near to the specified constant value.

If the signal from the downstream sensor varies from the constant value, this tells you that the catalytic converter is not working properly. Hence, the ECU switch on the ‘CHECK ENGINE’ light on the dash.