Re: 2001 Chevy Malibu automatic transmission problems?
Sure sounds like a restricted catalytic converter. You can pop out the O2 sensor in the manifold and see if there's any improvement. It may not run normally but should be able to see some improvement with the sensor out as now the exhaust has some way to escape. I wouldn't run it too far like that but none the less it's a quick and easy check. To do it right you'd need a backpressure gauge, old school vacuum/pressure gauge you can buy anywhere is all you need. There's a fitting you can buy that threads into the O2 sensor hole and the gauge gets hooked to that. Spec is 2psi max at 2,000 rpm. You would check at both O2 sensors, the second one is rearward of the converter. If the reading is above spec at only the front O2 sensor, you have a bad catalytic converter. If it's high at both sensor locations, your problem is rearward of the catalytic converter, collapsed pipe or restricted muffler.