Hey just wondering if a 3rd cat delete will make my truck sound better. I currently have a flow master 40 series with a 4.5 inch pipe on a 5.3L. Also will my check engine light go on if I delete it?
ajlaugh
You won't change a whole lot with it gone.
I got to ask though, why such a large pipe size? Going to a more normal size pipe will change your sound for the better more likely. Too large of a pipe size sounds strange on a motor that cant take use of it.
I got to ask though, why such a large pipe size? Going to a more normal size pipe will change your sound for the better more likely. Too large of a pipe size sounds strange on a motor that cant take use of it.
I'm not one to mess with emissions. I've seen too many people have too many engine light issues. Remember when your engine light does come on your computer is backing off timing and altering fuel trims as a safety effect for the engine. Anyone driving around with their engine light on is not running at full power. As the time stamp on the code gets older it will back off more and more timing and trim more and more fuel. The sensors have to communicate. Even though we might think of them as redundant they are serving a purpose. Imo leave emissions alone. You can easily modify your exaust without removing emissions.
The truck will never know the 3rd cat is gone. It's not monitored in any way.
You can remove all 3 cats if you wanted. Just need to get it tuned accordingly.
But in all reality, even if you did that, you wont gain much. It will be a little louder and the tone will change a bit. But there are no performance gains to be had.
If you want gains then get a set of long tubes and a good tune. Those will give a noticable bump in felt power.
You can remove all 3 cats if you wanted. Just need to get it tuned accordingly.
But in all reality, even if you did that, you wont gain much. It will be a little louder and the tone will change a bit. But there are no performance gains to be had.
If you want gains then get a set of long tubes and a good tune. Those will give a noticable bump in felt power.
Lots of misinformation here. It won't turn on your light. It's there bc in Cali they measure tailpipe emissions and plugging it up to the OBD reader so it will reduce tailpipe read emissions enough to meet Cali standards. If you remove it, your truck will be a tad louder id guess. If you remove the front two main ones it will be a lot louder not a little bit and will give id estimate 10-15 wheel hp gains but it's not worth it bc unless you have a special emissions guy it's never going to pass unless someone writes you an illegal tune like the diesel scandal you hear about in the news to trick the monitors. Otherwise they can make you a Tune where your CEL won't come on but when it's inspection time your rear o2 monitors and heated cat will show "not ready" so by the standards that's an automatic fail just like a CEL. Unless you find someone to "fool" that or a shop that can and will pass it when they show not ready it's way too big of a hassle going back to stock just for one inspection then back to race car mode
You will not come anywhere near close to 10-15hp gain by removing cats. I'd be shocked if a good tune could squeeze 2 or 3 extra hp out of it.
They really aren't that restrictive. You'll still have the manifolds, and those are more of a restriction than the cats are.
And any good tuner can have the truck run just as good with cats as without. And unless the emissions tester actually looks under the truck, or smells it, there will not be any indication they are gone by looking at the test monitors.
I have long tubes and "cats" and my tune has all the monitors come ready just as they always have. The rear o2 sensors are tuned out since even with the cats, they still were throwing a code for cat performance.
They really aren't that restrictive. You'll still have the manifolds, and those are more of a restriction than the cats are.
And any good tuner can have the truck run just as good with cats as without. And unless the emissions tester actually looks under the truck, or smells it, there will not be any indication they are gone by looking at the test monitors.
I have long tubes and "cats" and my tune has all the monitors come ready just as they always have. The rear o2 sensors are tuned out since even with the cats, they still were throwing a code for cat performance.
^ fake news. Please provide proof of those hp gains by only deleting cats. Or where the "estimate" came from.
It's not the 80s. Modern cats aren't restrictive.
And deleting the 3rd cat makes almost zero difference in noise. I did it to my last truck. And didn't do it to my current one. Not worth the hassle.
Sent from my iPhone using Tapatalk
It's not the 80s. Modern cats aren't restrictive.
And deleting the 3rd cat makes almost zero difference in noise. I did it to my last truck. And didn't do it to my current one. Not worth the hassle.
Sent from my iPhone using Tapatalk
I suppose it may vary from state to state on the rear monitors but you say "the rear 02 sensors are tuned out" = automatically fail inspection. Again may vary state by state. A tune alone is worth id estimate 20hp and 20tq I'd estimate. The headers another 15-20 each. Idk where you're gettin the research you've presented but I'd like to see it. I've been dealing in performance engines my entire life for the most part since I'd say I was 10 years old
Yes headers will get you the gains you claim.
Except OP doesn't have headers. So simply removing cats will not gain you the same amount of power as headers will. Also doubt you get 20hp from a tune alone with no other mods. Just look up dyno sheets from these trucks before an after tunes and headers. Headers are the most you'll gain short of getting into the motor. Otherwise just a tune doesnt bump power that much. Just GREATLY improved drivability
As far as the emissions monitors, when I plug my scan tool into my truck, which has long tubes with a catted y pipe, custom tune with the rear o2s "tuned out" the monitors all are ready and look no different than they did when the truck was stock.
I went through the same thing on my 01. The evap monitor would never come ready. Tuned it so it was ready. If the ecm is no longer looking for info, it doesnt see an issue so the monitors will all pass.
The emissions stations have no way of telling if its tuned or not. And they dont care either. As long as the computer shows no DTCs for the engine, and all the monitors are ready, it passes the vehicle and you get a sticker. And technically in PA you can have 1 monitor not ready and still pass.
Obviously isn't the same for all state, but PA is one of the worst for inspection/emissions.
Except OP doesn't have headers. So simply removing cats will not gain you the same amount of power as headers will. Also doubt you get 20hp from a tune alone with no other mods. Just look up dyno sheets from these trucks before an after tunes and headers. Headers are the most you'll gain short of getting into the motor. Otherwise just a tune doesnt bump power that much. Just GREATLY improved drivability
As far as the emissions monitors, when I plug my scan tool into my truck, which has long tubes with a catted y pipe, custom tune with the rear o2s "tuned out" the monitors all are ready and look no different than they did when the truck was stock.
I went through the same thing on my 01. The evap monitor would never come ready. Tuned it so it was ready. If the ecm is no longer looking for info, it doesnt see an issue so the monitors will all pass.
The emissions stations have no way of telling if its tuned or not. And they dont care either. As long as the computer shows no DTCs for the engine, and all the monitors are ready, it passes the vehicle and you get a sticker. And technically in PA you can have 1 monitor not ready and still pass.
Obviously isn't the same for all state, but PA is one of the worst for inspection/emissions.
Correct me if I'm wrong but the cat side of emissions works to calculate af ratios inline with mas. If you have a tune but the sensors arent there/ not functioning, wouldn't there be some disability to compensate for atmospheric pressures, temp and density? From what I know of emissions the cat sensors run in either open or closed loop. How would a tune make it possible to maximize your fuel efficiency? Sensors allow the computer to make intelligent changes while the vehicle runs. If you dont care about milage and you are only going for straight up power that's one thing. The stock computer works great but how would any tune without monitors like o2 sensors be better? I've never seen good results from handicapping the computer. Even the after market fuel injection systems have atleast one o2 sensor. When I had a bad cat and or bad o2 sensors I could watch my short and long term fuel trims going bsc. My gs numbers were also. Timing began to retard and you always lost power.
The rear 02 sensors are only there to monitor the performance of the cats. That's it.
It's the front (upstream) that matter. And those don't care if the cats are there or not.
So by "tuning out" the rear o2 sensors, it doesnt affect anything at all engine performance wise.
It's the front (upstream) that matter. And those don't care if the cats are there or not.
So by "tuning out" the rear o2 sensors, it doesnt affect anything at all engine performance wise.
For some one who has been dialing in engines since you were 10. You sure estimate a lot. And have a bit of misinformation.
But none of it has to do with the ops original 3rd cat question.
Sent from my iPhone using Tapatalk
But none of it has to do with the ops original 3rd cat question.
Sent from my iPhone using Tapatalk
I want to see the data where a tune gets you 20HP and 20 ft. lbs. of torque, not just an estimate.
I agree 100% with Eric. Just serious driveability gains.
I agree 100% with Eric. Just serious driveability gains.
Yeah and Intakes claim 15hp too. 15hp is the magic selling number!
Sent from my iPhone using Tapatalk
Sent from my iPhone using Tapatalk
I didn't look at the dyno chart but I'd estimate (you guys like it when I do that) 30+ at certain points in the curve
my buddy gutted the cats on his truck and had to do the O2 sensor spacers to get the CEL to go away. soon as he did those, back to normal. his truck sounded WAY better after he gutted them. he's got a bit older model (i think its a '06) so YMMV
to the original poster...
I have a 2009 with flowmaster original 40 series single in dual out with 3 or 3.5" tips. After a year or so I removed the third cat and while there was a little noise change its not really worth the $50-100 a shop will charge to do it in my opinion. I would say if you were just now getting exhaust work done for the first time the do it just for the heck of it. Other than that you aren't really gaining anything.
I have a 2009 with flowmaster original 40 series single in dual out with 3 or 3.5" tips. After a year or so I removed the third cat and while there was a little noise change its not really worth the $50-100 a shop will charge to do it in my opinion. I would say if you were just now getting exhaust work done for the first time the do it just for the heck of it. Other than that you aren't really gaining anything.
Good to know Trax. So if one of my cats ever gets plugged up, I can just cut it out and replace it with straight pipe? And if a downstream o2 sensor goes bad I can just ignore it? How do I tune out the downstream 02 sensors? I have an intune i3 I don't want a check engine light to be on. However, if an upstream sensor goes bad, I should replace it correct?19trax95 said:
In theory yes.
But you will need a custom tune done to be able to have it done.
And you will need your upstream sensors to be reading correctly as they would before.
It's not something that would be worth it for a bad sensor though. Just replace it. They are cheap and easy enough to do.
Really only time its needed is when going with headers in my opinion
But you will need a custom tune done to be able to have it done.
And you will need your upstream sensors to be reading correctly as they would before.
It's not something that would be worth it for a bad sensor though. Just replace it. They are cheap and easy enough to do.
Really only time its needed is when going with headers in my opinion
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
