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Catalytic Converter Questions and Answers - This category contains featured questions as examples. They relate to most vehicles.

Question: 1999 Plymouth Voyager mileage: 63,094. I just had my car fixed because my catalytic converter was clogged. The diagnostic machine said everything was fine. Could this happen from just normal wear? In addition, I now hear this rubbing noise on the front driver side, also, a lot of rattling. Someone said my shocks were shot. Could this be?

Answer: Catalytic converters plug usually because of a rich fuel mixture. Have exhaust gases analyzed to determine the correct mixture. Your shocks need replacing anytime there is excessive movement.

Question: 1990 SAAB mileage: 120,000. I had a blown head gasket and drove with it for quite some time. It got kind of bad and I was forced to drive the car out quite some distance to store it. Along the way, the engine was overheating and I began to lose a lot of power. I have since replaced the head gasket, and checked the compression on the cylinders. They were pretty even at about 130. The car still has difficulty with a lack of power. I was wondering if that lack of power could be caused by a clogged catalytic converter due to all of the fowled exhaust. I had never replaced the catalytic converter on the car.

Answer:  Yes, there is a good chance that the catalytic converter is plugged.

Question: 1990 Porsche 928s4 5.0 mileage: 129,999. Hard start - when started runs rough and no power or intermittent power. Was working fine before and after having Midas check my catalytic converters. Verdict on cats was bad. Temperature on engine side of catalytic, 300 degrees; temperature on muffler side, 210 degrees. Does this mean the engine could be having troubles due to catalytic malfunction?

Answer:  Could be! To test for a plugged converter, drill a small hole in the exhaust pipe right before the catalytic converter. Install a temporary hose fitting and attach a long rubber hose and a 0 to 10 pound pressure gauge. With the gauge inside the car, drive up a hill or accelerate and read the pressure. Normal is 2 to 3 pounds, restricted 4 pounds or higher. The drawback to this method is the small hole will need to be welded shut after the test; a minor job if you have a welder.

Answer:  Try replacing the Mass Air Flow Sensor. A weak signal from the sensor may be causing your problem. To test for a plugged converter, drill a small hole in the exhaust pipe right before the catalytic converter. Install a temporary hose fitting and attach a long rubber hose and a 0 to 10 pound pressure gauge. With the gauge inside the car, drive up a hill or accelerate and read the pressure. Normal is 2 to 3 pounds, restricted 4 pounds or higher.

Answer:  You may have had the incorrect catalytic converter installed but it sounds like the heat shields are not properly placed. If the engine is running “rich”, it will cause the catalytic converter to be hotter than normal. Have the engine fuel system checked.

Question: 1998 Ford Mustang mileage: 139,000. I recently noticed that my catalytic converter was glowing bright orange and it started smoking very badly. What do I need to do to fix the problem?

Answer: Your fuel injection is malfunctioning causing an over-rich condition. Scan your computer for fault codes, which should pinpoint the problem.

MORE: Catalytic converter questions and answers