Was talking to my grandson-in-Law this afternoon and gas mileage came up on our unit. I told him we would get 6mpg is not uncommon. He mentioned a friend that had a Ford Diesel, year unknown, that removed his cat converter and the fuel economy went up A LOT. By my sig, would there be any advantage? I did install a tuner from Blackbear in September. But have not towed to check how it works. I searched the generic question and got answers ranging from much more HP and 25% better mileage (Yeah, right) to it would run much worse and mileage would decrease....Just curious as to any answers.

This probably isn't the answer you want to hear but someone is going to say it anyways so it might as well be me. If you remove your catalytic converter then you will probably not be in compliance with California emissions laws. I don't know the laws for California but if sure you guys out there have some sort of inspection. Without those cats I'm sure you would fail the inspection and probably have to pay hefty fine if someone turned you in.

ramyankee wrote:Was talking to my grandson-in-Law this afternoon and gas mileage came up on our unit. I told him we would get 6mpg is not uncommon. He mentioned a friend that had a Ford Diesel, year unknown, that removed his cat converter and the fuel economy went up A LOT. By my sig, would there be any advantage? I did install a tuner from Blackbear in September. But have not towed to check how it works. I searched the generic question and got answers ranging from much more HP and 25% better mileage (Yeah, right) to it would run much worse and mileage would decrease....Just curious as to any answers. Trying to compare a gasoline cat converter to a diesel engine, diesel particulate filter is like comparing an apple to a poodle. You might pick up a hair in fuel economy at wide open throttle with no cat. The new cats flow really good. They have 600 HP cat on some cars. Your engine puts out less than 400 HP. Leave it alone.

Most OE cats are not restrictive as long as they have not had a melt-down. I know one V10 owner who removed his and nothing changed except it made the exhaust smell, so he put it back on.

Cats flow very well and you wont see any appreciable difference.

mrkoje wrote:This probably isn't the answer you want to hear but someone is going to say it anyways so it might as well be me. If you remove your catalytic converter then you will probably not be in compliance with California emissions laws. I don't know the laws for California but if sure you guys out there have some sort of inspection. Without those cats I'm sure you would fail the inspection and probably have to pay hefty fine if someone turned you in.Unless you are in a county that does not require the BI-annual inspection, I would think that you would be be in violation. What I have heard is that they look to see if everything is there that is supposed to be there. I do not have a diesel, but the gas vehicle inspections are tough enough to pass, especially when some of it is judgement calls. JMO

Hypothetical question regarding removing catalytic conv.

20 Replies

tempforce
Explorer
Jan 24, 2014
huntdog, the warranty statement is for others reading the post considering the same idea... don't be so inflexible...
Huntindog
Explorer
Jan 24, 2014
tempforce wrote:
yes and no.

yes, removing the e.p.a. junk and using a tuner and bypass/ false sensors will give you a better running engine and increase your mileage and power for the same amount of fuel. as long as you don't use the tuner to make gains over the stock tune, just for clearing codes and adjust to a better operating curve.

no, i wouldn't do it. as it will void your warranty and may get you huge fines, due to state and federal emissions. the factory computer will record any changes and any devices attached to it. (serial number and type of device, along with the current mileage when the device was attached).
How many 2002s have warranty left?
Redsky
Explorer
Jan 24, 2014
The companies that make the tuners state that the gain in HP from doing a delete is from 3-5%, hardly enough to matter. The gains in fuel economy that they advertise would require me to drive 50,000 miles to recoup the cost of the tuner.

All the truck manufacturers want to provide the best fuel economy they can to be competitive. It is impossible for me to believe that a guy in a garage can provide a better tuning specification for fuel economy than the hundreds of engineers working at Ford, GM, and Ram. It fails the sniff test.

The way to save money on fuel is to drive less and drive slower. Spending the extra $8,000 for a diesel pickup and paying the higher per gallon fuel costs and higher maintenance costs is not going to result in any real dollar savings for the average driver.
N-Trouble
Explorer
Jan 21, 2014
Save up for a diesel would be my advice. No use throwing good money at the 8.1 to try to make it economical. Aint gunna happen...
fireman41
Explorer
Jan 21, 2014
Have you tried other areas for better gas mileage?
You could look for tires that have low rolling resistance a better flowing air intake system, a good tune up.

But you kinda have to face the fact the you have a engine that one small engine size bigger than most engines out there and it just takes a lot of gas to run.
Volkov
Explorer
Jan 21, 2014
Cats aren't about reducing global warming. They are about reducing smog.
ramyankee
Explorer
Jan 21, 2014
It is not a lead foot. I am ALWAYS at the speed limit and when towing will never break 60 mph. When we leave home here to tow there is NO way to miss grades.
BurbMan
Explorer II
Jan 21, 2014
Geez even I get 7 towing at 70mph...

The 8.1 has O2 sensors before and after the cats (there are two cats, not just one) and the PCM is programmed to read and compare oxygen content before and after the cat to help trim fuel mixture. If you remove both cats, you will need to re-program the PCM so that it's not looking for those post-cat O2 readings. You may want to ask Black bear if they have done similar and what the results were.

As a side note, Banks Engineering is noted for their intake/exhaust upgrades, but they never made a kit for the 8.1 because the exhaust from the factory is already highly efficient. (They did make an exhaust kit for the 8.1 on the Workhorse chassis because the way that the exhaust was routed was inefficient, but that doesn't apply to GM-built vehicles with the 8.1.)

I did a lot of research on this, and removing the cats from the 8.1 is a lot of work IF you can find someone to re-program the PCM, and even then you may not see any improvement at all. I would say leave it alone.

I just went through the truck last year, all new stainless fuel lines, new fuel pumps (yes there are 2 in the Suburban), fuel filter, had the injectors ultrasonically cleaned and rebuilt, throttle body cleaning, new plugs and wires.

The result? Runs better than it ever did....but I still get 10 mpg around town and 7 towing!
powderman426
Explorer
Jan 21, 2014
If your only getting 6.5 mpg, my guess would be the problem is in your right foot and not the cat.
ramyankee
Explorer
Jan 21, 2014
I realize that california is restrictive. And we live way up in Northern california, the part that hopefully will become the State of Jefferson but that is for another thread. We do not have emission checks here.
In 1 year and 7 months Patti is retiring and we will NO LONGER be residents of california.....Will hopefully be setting on residency in IDAHO, where sanity reigns.
I was just curious from a possible savings view point.