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Ron, ASE Certified Technician
Category: Mazda
Satisfied Customers: 36069
Experience:  35 years as a automotive tech
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My fiance's 1984 Mazda RX7 1.1 rotary usually runs great.

Customer Question

My fiance's 1984 Mazda RX7 1.1 rotary usually runs great. right now it will not idle at all without choke pulled out. A small Popping noise under the car led me to what the Haynes repair manual calls a "catalytic converter thermo sensor". It is located just downstream of the converter and is mounted to the exhaust pipe with a 2 bolt flange, With a wire webbing insulation about 18 inches long going to something near the frame under the drivers door. It appears that exhaust gasses or white discoloration of the wire webbing insulation is just back of the sensor itself and may be the source of the popping noise. But I cant keep the car running long enough to get under it to check to see if this is the source of the noise.
Checking internet parts sources and local parts stores, none have come up with a thermo sensor but only oxygen sensors and none of those have the 2 bolt flange. All are thread in. I must assume at this point that the thermo sensor is the the same as an oxygen sensor. Am I right? And what is the white ash or discoloration? And would this part prevent the car from idling?
Submitted: 1 year ago.
Category: Mazda
Expert:  Ron replied 1 year ago.

Hello, my name is ***** ***** I am a professional here at Just Answer. I have noticed that your question was not getting a response and thought I would see if you still need help with this.I apologize for the delay and I hope I can still assist you with this here.

All your doing by pulling the choke is enriching the fuel mixture entering the engine, bad O2 Sensors will not usually cause the engine to not want to idle and or run . Due to the age of the car are you sure the catalytic converter is not just restricted. Why don't you try loosening the exhaust at the manifold till you have a healthy exhaust leak and see if the engine will now start and run. If it does then that usually means the converter is plugged up.