I have a 2004 Pontiac series 111,,ive changed plugs,coils wires,electonic ignition plate three times. All of that got rid of the miss,,however now im having a bogging between shifts between 1st and second only. Computer says catalytic converter flow restricted,however,could it be a problem going on before the converter? Could this be the map sensor giving a false read?

65

Asked by Jan 18, 2015 at 12:41 PM about the 2004 Pontiac Grand Prix GT2

Question type: Maintenance & Repair

although the trim is showing gt2,,my car is a gt series 111

2 Answers

69,445

Most likely the misfiring has ruined the catalytic converter. When an engine misfires the raw gasoline from that cylinder is sent from the engine, unburned, into the exhaust system where the catalytic converter must "eat" it. When this happens the converter is overheated and destroyed. The "honeycomb" inside the converter has melted and is now restricting the exhaust flow. HTH. -Jim

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130

I have experienced the same issue. The misfire causes raw gas to expel into the catalytic converter and clogs it up. Are you showing any evap codes?

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