Safe to drive without a catalytic converter?

newnameman

Platinum Member
Nov 20, 2002
2,219
0
0
So some fucker decided to steal the catalytic converter from my car. Obviously I'll get it fixed soon, but is it safe to drive like that for a while or do I need to get it fixed immediately?
 

jhu

Lifer
Oct 10, 1999
11,918
9
81
It's safe for you I suppose as long as you're moving ahead of the smog you're making behind you. Hopefully you live in LA because their air quality sucks anyway so a little extra smog there won't really be noticed.
 

Bignate603

Lifer
Sep 5, 2000
13,897
1
0
Besides the massive noise because your exhaust system has been cut before the muffler you should be ok. I probably wouldn't sit and idle for long periods of time because the exhaust will build up under your car.

You might get a check engine light depending on your car, some have pre and post cat 02 sensors and having the cat missing will freak it out.
 

HannibalX

Diamond Member
May 12, 2000
9,361
2
0
The car might run better, it might run worse, depending on what the engine is setup for. Did they take the O2 sensors too?
 

BassBomb

Diamond Member
Nov 25, 2005
8,396
1
81
sometimes the smell is really bad (if the cat is dying but not removed)
 

Raduque

Lifer
Aug 22, 2004
13,141
138
106
Your computer will freak out, and the car might use more fuel, but in the short term (couple months) I wouldn't sweat it. Long term (6mo +) there might be some damage due to running too rich, so i would throw on a new cat or an O2 simulator to get the computer to behave.
 

Colt45

Lifer
Apr 18, 2001
19,721
1
0
it'll be *loud*, that's about it. If you've got a newer car with oxygen sensors before and after the cat, it might confuse the puter a bit.
 

Eli

Super Moderator | Elite Member
Oct 9, 1999
50,422
8
81
Someone stole your catalytic converter? WTF? lol

That's the first i've heard of that.

But no, other than a probable check engine light, and sounding like a Harley with straight pipes, there shouldn't be any harm done.
 

jhu

Lifer
Oct 10, 1999
11,918
9
81
Someone stole your catalytic converter? WTF? lol

That's the first i've heard of that.

But no, other than a probable check engine light, and sounding like a Harley with straight pipes, there shouldn't be any harm done.

It's not unheard of. There's a fair amount of platinum in there.
 

MovingTarget

Diamond Member
Jun 22, 2003
8,999
109
106
It shouldn't hurt, especially if you drive an older car. Newer ones will probably have a check engine light go off, etc. I wouldn't worry about it in the short term. Long term however is a different story, especially if you live in a state that does emissions testing.
 
Sep 7, 2009
12,960
3
0
FYI they've gotten a lot cheaper at autozone and junk.. You may be able to find a muffler shop that'll help you out..

It's probably safe to drive but will throw codes and crap
 

sjwaste

Diamond Member
Aug 2, 2000
8,760
12
81
I have a very high mileage car, so I had to replace the rusted exhaust. I ended up going with larger pipe (3 inch) so I had to buy a new cat. They are surprisingly inexpensive as aftermarket, compared to what the dealer wanted. Hell, I loved how quiet the stock Supra exhaust was. If Toyota didn't want like $1200 for a new setup, I would've gone for that. But as it was, I got a 3" turbo to tip setup for a few hundred bucks. The cat was broken, as in pieces were loose in the casing, so I replaced with a Random Tech 3" piece. It was under $200. Just a thought, if you're looking for a replacement. A muffler shop can weld in new flanges and bolt in an aftermarket unit.
 

NutBucket

Lifer
Aug 30, 2000
27,034
546
126
Someone stole your catalytic converter? WTF? lol

That's the first i've heard of that.
Yeah, a year or two ago it was a fairly common crime here in SoCal. Naturally trucks made better targets since they have more ground clearance.

For most NA cars I would say that there may be a bit of a performance drop. FI cars will typically benefit from the removal of a major exhaust restriction
 

SooperDave

Senior member
Nov 18, 2009
615
0
0
It was a problem in the SF/Bay Area. It might still be. I don't live there now. It was usually the Japanese vehicles because mostly they bolt up and are easy to remove quietly. I was on my back pulling the tranny out of an F150 a couple of days ago and the tailshaft housing kept hanging on the crossover pipe. I was wishing it had bolt up flanges like you don't know.
 

Demon-Xanth

Lifer
Feb 15, 2000
20,551
2
81
Someone stole your catalytic converter? WTF? lol

That's the first i've heard of that.

But no, other than a probable check engine light, and sounding like a Harley with straight pipes, there shouldn't be any harm done.

Three got stolen from my work's parking lot in one day. Toyota pickups are usually the targets since theirs are easy to get to.
 

Viperoni

Lifer
Jan 4, 2000
11,084
1
71
I've heard of issues with cold air being able to reach the exhaust valves after turning the engine off. Dunno how serious it would be since there's a decent bit of piping to get from the cat's location to the head though.
 

Bignate603

Lifer
Sep 5, 2000
13,897
1
0
I had a catalytic converter rust off once (got to love heavily salted roads in upstate NY) and ran the vehicle for years with a piece of flex pipe in there held on by hose clamps. I think I had to double up the hose clamps to get a decent seal but it worked well enough.
 

brblx

Diamond Member
Mar 23, 2009
5,499
2
0
why not exhaust clamps instead of hose clamps? heh.

as long as the manifold and a few feet of piping are still there, i wouldn't worry too much about damaging the engine. it will probably set o2 sensor codes (downstream for sure), which will keep it in open loop, but that won't hurt anything.

driving around with that racket would be pretty douchey, though, and iirc the EPA fine is something like $2000 for a missing cat, if the cop that inevitably pulls you over really wants to stick it to you.
 

Bignate603

Lifer
Sep 5, 2000
13,897
1
0
why not exhaust clamps instead of hose clamps? heh.

Because I had hose clamps sitting there and they worked so I never thought much about fixing it. It was a duct tape and bailing wire sort of vehicle. ;) It was an '93 cherokee and I guess it was old enough that the computer didn't even notice, I don't think it had a downstream sensor.

The catalytic converter was the least of the problems caused by rust. The rocker panels had holes in it large enough to stick your hand through and there was a hole underneath the front passenger's footwell large enough that a person could fall through it. The carpet was all that kept your feet inside the vehicle. It was funny though, it still ran great even with the body falling apart around the drive train. If some jerk hadn't stolen it and crashed it I'd probably still be driving it as body panels just kept on falling apart around me. I would have eventually had to have replaced the catalytic converter because I would have needed to get new emissions tags but that was the only issue I think I would have run into.
 

Lotheron

Platinum Member
Oct 21, 2002
2,188
2
71
Three got stolen from my work's parking lot in one day. Toyota pickups are usually the targets since theirs are easy to get to.

SUVs/trucks/etc are targets not only due to the ground clearance, but the cats tend to be bigger too since they generally have bigger engines. I'm not sure if this equates to more platinum, but it would make sense.