guest234

So, we did the DEQ on my truck last week and came out clean as a whistle. Yesterday my Service engine soon light came on. Ran to Auto Zone for a check and comes up my cat on my R. bank has low efficiency in bank 2. Catalytic converter defective. Possible causes Engine misfire, large vacuum leak, oil leak into exhaust guides, piston rings. So, I don't know where to start. Hoping someone has tackled this problem and was successful. I do have an exhaust leak somewhere I've yet to try and hunt down. It's coming from under the hood. Maybe this could be the issue?

2000 F150, 5.4L, 138k miles, auto, 4x4, Dealer says engine was replaced 5k miles ago. Of course there's no proof.

techrep

iTrader: (1)

Clogged cat....what's DEQ ??

guest234

I apologize. DEQ is the air quality control in Oregon. Depart. of Environmental Quality. This is the test we have to take for exhaust gasses pollution. I was thinking plugged cat but they're so expensive I didn't want to just start throwing money at the problem without some advice.

guest234

So I found the issue I believe. After the first code telling me I had an inefficient cat I took it to a local exhaust shop. They did a code reading again. Another code popped up Auto Zone didn't tell me about. Something about an open loop regarding the fuel. He explained that when I first start the truck it's like a choke. It dumps in fuel until the engine comes to temp. then the loop is closed. Well apparently I had not noticed (being I am not the driver) that the temp gauge has been riding at cold for a week or so that's why the gas mileage has been bad. Need to know info.!! Exhaust shop mechanic told me to change the thermostat and see if that will do the job. Did that and now it's running at norm. temp. He said the cats may have been damaged but the only way to know is to drive it and see if it throws up the service engine soon light again. When I took out old thermostat half of it had been cut off from previous owners. They cut away the part with the spring and all. They also put Locktite on the steel bolts that goes into aluminum threads. Tell me I wasn't panicking taking out those bolts.
I wanted to thank you all who answered my call to help. I love forum boards for that exact reason. You're all great in my book.