98 4.0 Cat Converter

[TheMuffinOfEvil]

How bad does it screw the computer up if you don't have a converter. I know its illegal to not have one if you intend to drive on the street. I however need to know how bad the computer is going to freak out if there is no converter but the 02 sensors remain.

 

[Sasquatch_Ryda]

There is a catalyst monitoring sensor ( another 02 basically) that will not like not having a converter infront of it.

 

[TheMuffinOfEvil]

Any idea how badly its going to be upset. I can deal with error codes, but will it actually make it run poorly?

 

[James86]

I would imagine it would run leaner since the unburned gas leaving the cylinders isnt being burned in the (in this scenario "elsewhere") catalyst so the O2 sensor will try to lean it out to acceptable levels. I'm not sure if the computer pays any more attention to specific O2's though since you'd think that the engine would rely on the 02 sensors on each manifold to determine if its mixed properly. In short, I think it'd throw a code and run lean.

 

[Big Jim M]

The cats are so intergrel to the system that you simply CANNOT delete them without terrible results. I'd think that you may even burn valves and pistons if left off for a long trip.
Big JIm

 

[srteach]

I agree with Big Jim M.
The third O2 sensor will sense a rich condition, and tell the computer to lean the mixture out (emissions programming). The primary O2 sensors will tell the comp to rich the mix. They will fight and eventually burn the O2 sensors up.

All that aside, fuel is a cooling agent directly in the cylinders. You may burn valves. You may burn a hole in a piston. The system will cook the oil when lean, or wash it out when it goes rich. Fuel mileage will plummet.

I hate catalytic systems.

 

[Big Jim M]

I agree with Big Jim M.
The third O2 sensor will sense a rich condition, and tell the computer to lean the mixture out (emissions programming). The primary O2 sensors will tell the comp to rich the mix. They will fight and eventually burn the O2 sensors up.

All that aside, fuel is a cooling agent directly in the cylinders. You may burn valves. You may burn a hole in a piston. The system will cook the oil when lean, or wash it out when it goes rich. Fuel mileage will plummet.

I hate catalytic systems.

Oh no teach! You actually LOVE catalyic systems. They are saving us tons and tons of fuel.. Without them we'd still be getting 10 mpg on most of our vehicles.
Yeah I know it took lots and lots of engineering to get them right but look what we can do now. My new GMC 1/2 ton pickup has an average fuel milage for the first/last 30K of 15.4 mpg! That wouldn't be possible without the cats. It's a 4x4 and I drive it 85mph on the interstate and then make short trips around town. All this driving and still has an average half again better than just a few years ago before all the engineering took place.
Gimme cats anytime over the old carbed engines.
Big JIm

 

[TheMuffinOfEvil]

Any specific brand of cat I should put back on, or will a generic high flow one do? Anyone have any recommendations?

 

[Big Jim M]

Well muff what I'd do is try to find a store brand with the best warranty.. EPA has such a hold on these things I doubt you could get a bad one.. So to me, only the warranty matters.
Big JIm

 

[srteach]

I hate the damn things for the problems they can cause, not the fuel savings.

 

[Ak_Ranger]

Oh no teach! You actually LOVE catalyic systems. They are saving us tons and tons of fuel.. Without them we'd still be getting 10 mpg on most of our vehicles.
Yeah I know it took lots and lots of engineering to get them right but look what we can do now. My new GMC 1/2 ton pickup has an average fuel milage for the first/last 30K of 15.4 mpg! That wouldn't be possible without the cats. It's a 4x4 and I drive it 85mph on the interstate and then make short trips around town. All this driving and still has an average half again better than just a few years ago before all the engineering took place.
Gimme cats anytime over the old carbed engines.
Big JIm

Thats it?! only 15.4 mpg! I had a 99 SIlvarado with the 5.3L and could get 19mpg on the highway, 16 in town and it only dropped below that if I had it in 4wd when the snow was coming down hard. You must have the 6.0 im assuming Unless you ahve a heavier foot than I do lol.

 

[Big Jim M]

Nope! Nope! Nope!!

Thats it?! only 15.4 mpg! I had a 99 SIlvarado with the 5.3L and could get 19mpg on the highway, 16 in town and it only dropped below that if I had it in 4wd when the snow was coming down hard. You must have the 6.0 im assuming Unless you ahve a heavier foot than I do lol.

Mine will get the 19 also but there is a fuel computer in the new ones that gives me the milage average for the life of the vehicle. I can delete the average and start over anytime I want to...but I thought from the begining that I'd like to know what my lifetime average was so I have never deleted it.
In the old days 11mpg on a trip was great.. Nowadays 17/18 is common. What a difference a computer makes.
Big Jim