On a cold crank the enginge idols rough until it warms or the accelerator is pressed down. Also runs rough going up hills or towing. Check engine light is on and is throwing the code for bank 1 to lean and cat performance below threshold. Cats have been tested, good. Fuel trim tested, good. One mechanic said noth8ng is wrong with it well, there is.

Any suggestions??

 

Mileage? Maintenance?

 

like Squisher said... we can not SEE your truck or your odometer.


spark plugs all 16,
spark plug wires.
throttle body cleaning.
vacuum leak.
O2 sensor, fuel pump pressure...

and 30 other things.



Clearly there is something WRONG.. computer is posting Codes.. change mechanics... this one has Issues with his training.

 

I'd be interested to know how the cats were tested good? I've read of more than one case now of catalytic converters causing misfires to no fires on these motors.

 

140,000 miles, maintained as suggested by ford.
Air flow sensor is clean, 16 plugs changed, lower o2 sensors new.
With catalytic converter they punched a hole in front and behind it in the exhaust pipe. The air flow pressure was equal. Is that correct procedure?
I am not a mechanic by trade i just pretend on weekends because i cant afford a real one to keep sending me on wild goose chases.......

 

First off I'm no mechanic myself but I am unaware of a flow test that can be done as you stated your mechanic has? Also was this test done in a bay or driving? Not saying whatever they did isn't proper but there's a couple/few other ways to effectively and simply check a cat. Also if they did their flow test at any kind of load/rpm on the motor the flow shouldn't be equal before and after, there is always some restriction with cats, even high flow aftermarket ones.

For myself I would rattle/bang the cats exhaust with a rubber mallet to listen for loose parts/bits in it. Then warm the vehicle right up driving it around and measure with an infrared gun the temp of the exhaust pipe immediately in front of the cats and immediate behind. The temperature after the cats should be higher if it's working properly. You can also test vacuum recovery to see if there is a restriction in the cat/exhaust. You can also loosen or remove the exhaust in front of the cats and drive it to see if the condition/misses are still present. Obviously there will be loud exhaust leakage when doing that.

Cats are original? The plugs were replaced when? As regular maintenance or in an attempt to fix this issue? Any modifications to the truck?