catalytic convertor???

[butterfingers]

Say someone (I wouldnt know who ) gutted out there catalytic convertor because it plugged up and they didnt want to fork out $200-250 for a new one, would this cause the vehicle to have visable exhuast when it is ideling. For instance the vehicle smokes a little when at idle and It has done it since somone removed the catalytic convertor. The vehicle is an 89 and it didnt screw up any sensors or turn on any lights. Just wondering if this would cause it to have visuale smoke? Thanks

[LTJGWorth]

I think i heard of someone else having a similiar problem. I took the catalytic converter off of my 84 GMC Jimmy when I installed dual exauhst and it smoked a little bit at start up i think. As long as it's not smoking when you give it gas or are driving down the highway it should be ok. Removing the cat could cause some smoke, since the cat filters out some things.

[praisethelowered]

Your cat burns off excess hydrocarbons in the exhaust, so removing the cat may cause some smoke. I've noticed that the exhaust also tends to smell a little more after removing a cat.

[butterfingers]

yeah I did notice it smelled more

[BleedDodge]

Yeah, on every vehicle I've seen that has no cat, the exhaust will leave vapor trails like cars with cats do when it's cold outside. The cat has something to do with it.

[moparboy99]

my question is that I want to do this to my 98 ram so that the pipes will be loader but its got the second o2 sensor how do I get around that

[Dodgeintheblood]

There is several methods to get around the 2nd o2 sensor, there is a resistor that can be installed for one. I am not sure about the details some of these other guys can fill you in on that... If you have access to a welder what I did was to mount the sensor to the outside of the pipe up near the first sensor and enclose it. (box it in) The 2nd sensor only reads heat(indicating it is in the exhaust) and it has to read more o2 than the first sensor. With it outside the exhaust pipe it reads more o2 and mounted on the side it reads heat... Works great, at least it did on my 2001...

[BleedDodge]

My grandpa's truck only has the pre-cat sensor tapped into the exhaust path, the post-cat isn't even there. It somehow doesn't throw any codes, and the gas mileage is good.

[dirty dan]

You're probably burning a little oil. The hot catalytic converter normally burns off the oil that gets by the combustion chamber. That's why you hardly ever see a car that smokes on the highway anymore. Back in the '70's, probably 25% of the cars on the road had a visible exhaust. Today's cars are still burning the oil, the cat just cleans it so well you can't see it when the engine's warm.
Depending on how much oil you're burning, this could have been what caused the cat to clog.

[BleedDodge]

That's pretty understandable. My truck shoots soot out of the pipes like you'd see on a diesel truck, but this is a V6 gas engine. The cat has been done once, and I'll probably need to do another one or make "adjustments" to the existing one since the dealer said they fixed it but they actually didn't.

I hate these stupid things.

[dirty dan]

If you're sooting out black, you're running rich which will kill a cat in short order.

[BleedDodge]

Really? That's what I thought too but everyone that I talked to said they thought it was running lean because it had that hot exhaust smell, like headers, you know?

My gas mileage is very bad. I get about 12-13 mpg on the highway at best.

[dirty dan]

A lean burn will really heat up your exhaust manifolds but it won't leave black smoke/soot. The black is unburned fuel. Also I've never heard of a lean burn ruining a converter.