Catalytic converter

[wagonmaster69]

I have an 1999 explorer 4x4 V6 OHV with 262,x.. miles on it.
How can you tell if your catalytic converter is going out?

 

[shucker1]

Emissions Test.

 

[German Engineer]

I have an 1999 explorer 4x4 V6 OHV with 262,x.. miles on it.
How can you tell if your catalytic converter is going out?

The emissions test, or if you have a good OBD2 scanner, then you can:
Check the O2 sensor live data, especially the data of the downstream O2 sensor behind the converter.
And diagnose the converter performance this way.

Here is a link worth reading on that: OXYGEN SENSORS

If you read there and get or scroll further down you will find a section explaining:
"How does a downstream O2 sensor monitor converter efficiency?"
That link will explain what to look for in the live data on the upstream and downstream O2 sensors. If you do this you will also have to monitor the live data at various driving conditions, especially also under load and the engine needs to be running long enough for the converter to be heated up and reach the proper operating temperature.

If your OBD2 scanner is not capable of presenting live data then you might possibly also be able to get an idea by clearing all the error codes and waiting for your emissions related I/M readiness monitors to be completed after a full drive cycle.
I'm not 100% sure about this at the moment, but I believe one of the I/M readiness test the PCM performs also checks the converter performance and if that passes or fails you would also have a relatively good idea.
The PCM of the 99 Explorer does not have all 11 I/M Readiness tests available and I'd have to look which tests it performs and which not. But if your scan tool shows all the available I/M readiness tests are passed then it should be fine. (But please check back if it really runs a test on the catalytic converter performance.) They can all only either pass, fail, be incomplete, or they are not available.

The conditions necessary for a full drive cycle to be completed and to run and complete all the various tests is described here:
Ford Motor Company Driving Cycle

If you don't have an OBD2 scanner, then you won't really be able to diagnose it yourself.

For a truly complete and fully reliable way to determine you would need professional test equipment with a probe measuring the actual chemical composition of the gases coming out at the exhaust.

 

[shucker1]

For a truly complete and fully reliable way to determine you would need professional test equipment with a probe measuring the actual chemical composition of the gases coming out at the exhaust.

As well as inlet so you can get a good Delta value of the changes in composition.

Quick test but not certified would be to drive the vehicle a few miles then bring it back to the driveway and immediately use an IR Temp gun to check inlet and outlet temps while the engine is still running.

If the Cat is working your outlet temp will be higher than your inlet temp.

Cats actually "Burn" if working correctly thus the temp rise.

 

[CDW6212R]

... or the backyard mechanic way(where's that Russian guy), drill a hole in front of the converters, and check the air pressure there. Can you use a tire pressure gauge for that? I bet that other guy has tried it, or will soon.

 

[shucker1]

or the backyard mechanic way(where's that Russian guy), drill a hole in front of the converters, and check the air pressure there. Can you use a tire pressure gauge for that? I bet that other guy has tried it, or will soon.

Russian Guy took his converters out. Not Needed there and piece of junk.

Tied together several round sections of fence post from neighbors yard with wire from local phone pole and hose clamps!

 

[J_C]

Do you have some symptom that leads you to believe it's going out? Until some function of the engine goes south and subjects it to soot, unburnt fuel, or coolant, or it just rusts out, it is meant to last the life of the vehicle.

Granted, "life of the vehicle" is a concept that varies based on who you ask. IMO, Ford doesn't tend to build with 20 year lifespans in mind, yet here we are, many of us with 20+ year old Fords.

 

[donalds]

The emissions test, or if you have a good OBD2 scanner, then you can:
Check the O2 sensor live data, especially the data of the downstream O2 sensor behind the converter.
And diagnose the converter performance this way.

Here is a link worth reading on that: OXYGEN SENSORS

If you read there and get or scroll further down you will find a section explaining:
"How does a downstream O2 sensor monitor converter efficiency?"
That link will explain what to look for in the live data on the upstream and downstream O2 sensors. If you do this you will also have to monitor the live data at various driving conditions, especially also under load and the engine needs to be running long enough for the converter to be heated up and reach the proper operating temperature.

If your OBD2 scanner is not capable of presenting live data then you might possibly also be able to get an idea by clearing all the error codes and waiting for your emissions related I/M readiness monitors to be completed after a full drive cycle.
I'm not 100% sure about this at the moment, but I believe one of the I/M readiness test the PCM performs also checks the converter performance and if that passes or fails you would also have a relatively good idea.
The PCM of the 99 Explorer does not have all 11 I/M Readiness tests available and I'd have to look which tests it performs and which not. But if your scan tool shows all the available I/M readiness tests are passed then it should be fine. (But please check back if it really runs a test on the catalytic converter performance.) They can all only either pass, fail, be incomplete, or they are not available.

The conditions necessary for a full drive cycle to be completed and to run and complete all the various tests is described here:
Ford Motor Company Driving Cycle

If you don't have an OBD2 scanner, then you won't really be able to diagnose it yourself.

For a truly complete and fully reliable way to determine you would need professional test equipment with a probe measuring the actual chemical composition of the gases coming out at the exhaust.

Here are the obd2 readiness tests and Pcm etc
. on my 99
Using forscan

 

[wagonmaster69]

I was wrong on my diagnosis cause it was stuttering while driving.
Its either the injectors or coils.

 

[German Engineer]

I was wrong on my diagnosis cause it was stuttering while driving.
Its either the injectors or coils.

Did you check your fuel pressure?