2006 Mercury Mountaineer Engine noise

It does sound like the converter is plugged. Remove the O2 sensor before it to see if it runs better or remove the converter itself if you can.

Let me know what you find. Also, if the check engine light is on, let me know what codes are stored in the computer.

If the converter is bad, you should be able to get an aftermarket one for around 200.00. Based on where you live can increase or decrease the cost. However, for 1500.00 dollars, it should be gold plated. LOL

One other thought. When the engine is warm and you have driven the vehicle, leave it running and look at the catalytic converter. See if it is red hot.

If you remove the sensor, that will be a (small) place for the engine to breath if the converter is plugged. So remove the entire sensor from the exhaust.

Keep in mind, there will be an exhaust leak there. If it is proven that the converter is plugged, I don't recommend any distance driving. Honestly, they make universal converters. You basically cut the old one off and replace it with the new and clamp it in place.

Also, without the sensor, the computer has no idea as to how much fuel the engine needs to run. As a result, it goes into what is closed loop providing as much fuel as it can to run the engine.

One last thing. If the converter is plugged and getting red hot, like most do when plugged, they are EXTREMELY hot and can cause a fire.

Let me know if you have other questions. Thanks for your service to our country. Many of us still appreciate it!

Joe

With the V8, there are two converters, and yes it your description sounds like you see them. Check for the sensor before the converter or even in the exhaust manifold.