Bad MPG after catalytic converter removal

Long time reader here, popping my thread posting cherry with this one. I recently removed my catalytic converters (both pre-cat and the rear) because they became clogged. I then installed spark plug non-foulers on the oxygen sensors because of course my computer threw a CEL. This I was hoping would get the sensor itself out of the actual pipe, letting less oxygen to it. While my truck is running fine, I still find that my gas mileage has dropped a noticeable amount. My assumption is that the oxygen sensors are still "tasting" too much oxygen, thus telling the computer to send more fuel. Could I be right... could I be wrong? I have pondered on the option of stuffing something along the lines of steel wool, into the bottom piece of the non-fouler to let it have even less o2.

 

I suggest that you replace your converter as I understand there is a hefty fine.

 

That's out of the question for now lol. I live in east TN, and in a county that does not do emissions testing. Around here, finding a truck without a catalytic converter is as easy as finding a hooker with an STD

 

I don't think there is a quick fix to your problem. With the cats gone the o2 sensors are going to throw a code putting you into a 'default' safety mode. That leads to your engine running rich until you have the problem remedied.

 

The O2 sensors before the catalytic convertors can be screwed in without non-foulers. These are the ones that set your fuel trims. The rear O2's are the ones that check for cat efficiency, and will most likely need to be replaced with O2 simulators like what URD sells. This will tell the PCM that the cats are always working, even when they are missing.

 

Thank you all for your input, my question has pretty much been answered! I just wanted to make sure I had the problem narrowed down to the sensors and didn't have a malfunction in another area. I'm gonna try the steel wool trick, and if it still throws the code and is sucking down gas I'll go the simulator route.

 

REPLACE YOUR CATALYTIC CONVERTERS ALREADY!!!! YOUR TRUCK IS RUNNING LIKE CRAP WITHOUT THEM AND YOU WILL BURN OUT YOUR VALBVES SOONER!!! Just replace your cats with one converter it is as easy as getting a wrecked tscomas good converter and fixing your exhaust system to run into just one.

 

so you think the o2 sensor being out wont effect the PID loops that the ecu uses? How else will it be able to tell how it is tuned?

 

SO what does the front o2 sensor do. URD only sells a rear

 

Just cause you can doesn’t mean you should. I thought the hole in the ozone looked a little bigger today.

 

Deleting smog items on an electronic controlled truck is never a good idea.

 

So you removed an essential component(s) of the ECU system, and you're wondering why you MPG went to shit? OK.
Back in the 70's when CATS were in their infancy, we could get away with these kind of shenanigans. Some establishments even sold 'test pipes', that eliminated the converter for 'test purposes' only, of course. This was before ECUs controlled everything but, well, everything..
Good luck, somebody has a hack I'm sure.

 

I wouldn't use the steel wool it will just get hot and burn up, if yours is a 4x4 gutting the converters wont make that much difference ,we used to pull the converter and use the test pipes to experiment, for 1/4 mile performance , it did improve the performance but these were high performance vehicals not off road machines, I would put the converters back on and enjoy your truck , it was designed to run its best with the converters , unless you want to buy a pre 74 vehical then you can do just about any mods you want and be legal

 

Lol, not only is this a 5 year old thread but why are people so worried about deleting their cat....

Lmao, imagining thinking that our vehicle emissions are actually making that big of a difference to global climate change/ozone layer.

 

@tupac its my understanding the upstream sensors measure air/fuel mixture and the rears basically measure catalyst efficiency. With deleted cats, the front sensor readings wouldn't change, which is why you would only run 02 sims on the rear (after the cat)

 

Yea the point of a rear 02 sensor is just to make sure the cat is working properly