Defective catalytic converter

A defective catalytic converter can cause many problems with the exhaust system, and can lead to a reduction in engine power. The catalytic converter is used to clean certain elements from the exhaust gases after they leave the engine but before they enter the atmosphere. If it is defective, the gases can escape uncleaned, or alter the engine performance by creating a build up of pressure in the exhaust system.

Table of Contents

• 1. Symptoms
  • 1.1 Vehicle Backfires
  • 1.2 Engine Stalls
  • 1.3 Exhaust Blow Black Smoke
  • 1.4 Exhaust Abnormally Loud

Symptoms

A defective catalytic converter will alter the flow of exhaust gases from the engine. This can create a build up of pressure inside the exhaust manifold which will alter the combustion process. The gases may not be able to fully escape the combustion chamber. This will alter the mixture of fuel/air for every piston stroke.

Vehicle Backfires

A build up of pressure can alter the fuel/air mixture in such a way that fuel enters the exhaust manifold and is then ignited. This will cause a backfire.

Engine Stalls

If the defect in the converter causes a restriction, the exhaust gases can reenter the combustion chamber and dilute the fuel/air mixture. This will reduce the power of the pistons strokes, which can lead to stalling as the pistons may not be able to maintain their momentum.

Exhaust Blow Black Smoke

Black smoke from the exhaust is a sign of excess fuel in the system. A build up of pressure may keep some of the fuel out of the combustion chamber on one stroke, but let the remainder plus the next allotment in on the next one. The alteration of the fuel/air mixture will alter the composition of the exhaust gases.

Exhaust Abnormally Loud

If the converter is permitting exhaust gases to escape, the noise of the engine will not be dampened by the muffler. This will produce a louder sound exhaust as the sound waves escape prematurely.

If the gases are escaping before the converter, the exhaust will contain more pollutants. If the gases escape after the converter, they will have been cleaned, but the noise will not have been dampened. If the gases escape from the middle of the converter, they may not be fully cleaned.