How I Figured Out Exhaust Restriction (Clogged Catalytic Converter)

In this video I'll show you how I figured out that this 2001 Ford Escape 3.0L had an exhaust restriction or a clogged catalytic converter. I started by connecting a vacuum gauge to the intake manifold and measured the vacuum present when the vehicle was at idle. Usually a normally running engine will have somewhere around 18"-22"hg of vacuum at idle. I had around 12"hg at idle. I also revved the engine and held the throttle at around half throttle. When I did this the vacuum immediately went down to 0 and stayed there. On a normally operating engine the vacuum would go down initially when opening the throttle but is would quickly go back up. As mentioned the vacuum stayed at 0 when the throttle was held. So, I knew I had a restricted exhaust. The next step was to find out where the restriction was. I suspected a common restriction just because of the very poor performance of the engine. But, for grins and giggles I checked the cat converters by removing the O2 sensors and inspecting them with a bore scope. I did not see anything obvious so the next thing I did was run the engine with the bank 2 sensor 2 oxygen sensor taken out. Both the front head and the rear head are joined together by a "Y" pipe so removing this O2 sensor would alleviate any back pressure for both heads. (Note: You have to be very careful when doing this as you can damage your vehicle by exposing parts to the extreme temperatures of the exhaust gas that will come out of any O2 sensor port. You could even catch the vehicle on fire. If your O2 sensor port is in an enclosed area and exhaust cannot be safely vented from said exhaust port without damaging close by parts or catching the vehicle on fire then It would be my suggestion to NOT DO IT! Try finding the restriction by some other means such as taking sections of the exhaust of and inspecting sections internally with a bore scope.
USE THE METHOD OF RUNNING THE VEHICLE WITHOUT AN O2 SENSOR IN AT YOUR OWN RISK!! YOU CAN DAMAGE YOUR VEHICLE AND START A FIRE!! Also Note: I had to remove a splash shield so that it would not become damaged) Back to my story.... So I ran the vehicle without this O2 sensor in and it ran very well. So, I had a restriction in the exhaust that was common to both banks of the engine. Back cat, the cat converter after the two front cats, was suspect. Conveniently the back cat has a flange just in the front of it. I disconnected this flange and there it was. Cat converter material from the front cats had clogged the exhaust at this location. New converters and cleaning the material from exhaust was needed. And that's it in a nut shell.

Note: keep a fire extinguisher near by in case of fire.

Now, this video just shows how I discovered that the exhaust was clogged on this particular vehicle in this particular way. Though I show some diagnostic techniques this video is not comprehensive when It comes to showing you how to properly diagnose your vehicle. The video has very good information but it is not comprehensive. I would suggest using a repair manual.

Also, as a rule of thumb, I would suggest waiting at least an hour before handling exhaust and exhaust components after the vehicle is ran. If you don't you could end up with a very serious burn.

Also, It is good to note that there is usually a root cause of the exhaust becoming restricted. So, further diagnosis may be needed.

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Barbour's Auto Help is not responsible for any damage or personal injury incurred in the process of performing any auto repairs done by you the viewer. Automotive repair is extremely dangerous. Repair your vehicle at your own risk. It is the viewers responsibility to verify all information and procedures as outlined in YOUR REPAIR MANUAL AND OWNERS MANUAL FOR YOUR VEHICLE. Owning and using a repair manual suited for your vehicle is essential for correctly and safely performing ANY repair to your vehicle. Always wear safety glasses and heed all instructions for use applicable to any piece of equipment you may use. Due to circumstances out of the control of Barbours Auto Help, Barbours Auto Help makes no guarantee that by the use of the information given in this video a quality repair will be made. Barbour'sAutoHelp makes no guarantee that the information provided is totally complete, syncronized and accurate. Verify everything using an appropriate repair manual. Follow the repair manual over this videos content. You can do it. Do it right and do it safely.

Repair your vehicle at your own risk! Barbour's auto help does not guaranty a proper repair using these techniques.