On my 97' f-150 4x4 4.6L I have been getting this god oughful burnig greese smell on the passenger side and it looks like its comming from a breather and/or overflow tube in the engine compartment on the passenger side by some vacume lines. Also at this time the truck is sputtering missfireing and throwing up a ck/engine light code p303 and when you drive it the light flashes , witch is not good for the converter Im told. It has the original exhost. I also resantly changed all 4 o2 sen.
When I depress the throtle it sounds like the cats are rattleing driving or not. What the heck is going on ? Im mad and this isnot good.

milage 90000
new tune up summer 2002

 

It's quite possible that you have bad cat's, but that is unusual for cats to go out this early, unless you have alot of miles on the truck. I'm assuming that you drive the truck under normal circumstances. For the cats to go out this early, the engine must have been running very rich and dumping alot of excess fuel into the converter, hence, the converter can't take all that fuel and burn it off which would cause it to clog. Fix whatever the computer is throwing the code for and replace the converter, or as an alternative you can gut out the cat and run around like that until you can get a new one for it. I wouldn't reccomend running around too long with a gutted cat because the engine is desinged to run with a cat.

I have a 91 F150 with 4.9L in it. I took the cat off and put a y pipe behind the body of it and out the back. Sounded kinda odd but not too bad. After a while I noticed my gas mileage had dropped by 5mpg and the truck just never ran right. It ran ok but not the way it used to. I put the old cat back on and it smoothed out and my gas mileage went back up. Hope this helps you out

91

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