Removing cats

[JohnnyReb]

Are there any performance problems from removing the cats off a 3.0? My muffler has a pretty big leak and the exhaust pipe is dented and damaged from off roading. Since I'm moving out of state, I had decided to remove the cat as well and just put on a Thrush exhaust.

The only thing stopping me is that I've heard some vehicles have side effects from removing the cat. Is this the case with the 4runner?

If the 4Runner is fine with removing the cat, anyone got any idea about how much more power and mpg I could gain?

 

[DC runner]

Your truck is that age of a vehicle where you won't see much negative impact, but don't expect much positive impact either.

The notion that removing a cat will improve performance dates back the the 70's when you had mainly carb'ed vehicles with the first generation cats on them that were very restrictive and an engine absent any kind of computer control to bring things to peak.

Anyway. I am pro-cat for a bunch of reasons, but I did just want to say you should be fine. Depending on your vehicle and if you have an after cat sensor, you may get a code.

I don't remember..... that model may have just 1 sensor, pre-cat, and not even be an issue.

On newer cars, like mine (4th gen), not having a cat can cause a whole host of issues.
I owned a 3.0 v6 (1990) and I had the entire cat back unbolt (old, and loose) and drove for a bit before I could get under there and fix it. (on a trip).

The only indication something was up was the noise... I never popped a check engine.

 

[fourwd1]

One question, do they have emissions testing? Without it you'll fail.

 

[JohnnyReb]

No, no smog control where I am moving to.
Thanks for the input DC Runner. I have only one sensor and it is pre-cat so I am not too worried about it. I didn't expect a huge gain in mpg, but I figured that since first of all it is the factory cat and second off my stock muffler has a huge leak, I'm hoping the combination of removing both will get me at least a noticable bump in mileage.

Having said that, this project is only costing me a 12 pack so even if it saves me three gallons (that's right, I buy good beer) of fuel, it paid for itself.

Anyone have any quick and cheap ideas on how to pinch mileage out of a 4Runner? I got plugs, wires, clean air filter, oil change, rear diff fluid change, fuel filter, removed my roof rack, and got the tires filled. Anything else that the 2nd gen 4runner can lose?

 

[92-SR5]

I'm waiting for my test pipe to come in the mail. I'll let you know if there is any difference once I bolt it in. I have a 22re though.

 

[pdsnowrunner]

cat

i have a 22re. i took the cat off and pushed all of the stuff out of it. so now there is just a cat caseing. i dident have to but a test pipe or anyting so it was east and cheap, and it still looks like i have a cat.

 

[JohnnyReb]

i have a 22re. i took the cat off and pushed all of the stuff out of it. so now there is just a cat caseing. i dident have to but a test pipe or anyting so it was east and cheap, and it still looks like i have a cat.

Did you notice any boost in mileage? And what about the stock muffler? Do you still have it on?

 

[jmccawley96]

roof rack

Hello there and Do you still have that roof rack you removed? I am close to Orange county fl are you??

JOE

 

[JohnnyReb]

Hello there and Do you still have that roof rack you removed? I am close to Orange county fl are you??

JOE

Sorry Joe, Orange County CA, not FL

 

[92-SR5]

Well I put my test pipe on. My exhaust is a lot louder now and more ricey sounding. Not horrible but noticeable. Only have had it on a day so I can't report anything on fuel economy.

 

[BucknutBob]

There are plenty of high-flow cats out there to replace your factory one, so there's really no good reason to get rid of it altogether. The 2nd Gen uses O2 sensors before and after the cat, so you may throw a code. As for mileage, proper tuning, proper tire inflation, and reasonable driving are your best bets--there is no magic cure like the mythical chip remedy. The primary problem with 2nd Gen's is simply too much weight for the available power, so the engine has to fight more, and therefore returns fairly poor mileage for it's size.

 

[92-SR5]

There are plenty of high-flow cats out there to replace your factory one, so there's really no good reason to get rid of it altogether. The 2nd Gen uses O2 sensors before and after the cat, so you may throw a code. As for mileage, proper tuning, proper tire inflation, and reasonable driving are your best bets--there is no magic cure like the mythical chip remedy. The primary problem with 2nd Gen's is simply too much weight for the available power, so the engine has to fight more, and therefore returns fairly poor mileage for it's size.

Mine only has a o2 sensor before

 

[JohnnyReb]

Mine only has a o2 sensor before

Same, pre-cat is my only oxygen sensor

 

[BucknutBob]

Once again, another mid-Gen change to make me sound stupid. So some had 2 O2's, and some had only one. Live and learn.

 

[the_dingman]

My 22RE sounds much better without the cat, and does seem to have a bit more power.

I removed mine because a p/o did a crap job on the exhaust, and I kept blowing out the gasket on the front of the cat, so I put in a straight pipe.