14.7 is optimal efficiency wise, not power wise.
Delete the cats or not?
- Thread starter Fishtaco
- Start date
I feel like I'm being calmer about this than I should be. I haven't copied and pasted a thing. It sounds like you don't understand how ratios work let alone an engine. You said you can add different amounts of fuel or different amounts of air but it will still always equal 14.7?
Look man, I know it's not fun having somebody tell you you don't understand. I get it. I don't feel like I've been snippy or rude at all up to now. You don't understand what tuning with a wideband is. You think engines should always shoot for 14.7 a/f ratio in all parts of the map. You think 6hp is what's out there to be had over stock.
I can assure you, you don't understand what you are talking about. I'd be happy to discuss and spend the time to provide you with links to show you what I say is true, but I'm not going to waste my time if you are going to continue with the attitude.
Rubicon88
TJ Addict
I was rather crystal but allow me to try one more time....
14.7:1 is not an amount. It's a ratio.
The amount of air and fuel can change all day long but the ideal goal for proper combustion is 14.7:1
If more fuel is being dumped then more air is needed to maintain that optimum ratio. If less fuel is being dumped we need less air to try and hit that 14.7:1
Now please tell me that time you understood exactly what I meant that the amounts change but it's all relative to one another to maintain that proper ratio.
It's a 4.0 Jeep engine. I say Jeep because it is in fact a Jeep. If being used like a Jeep with a stock 4.0 then by all means how often are we needing to make the ratio rich to eek out a tiny bit of horse power....at WOT...and at what expense?
Has a cam change happened? Head work done? You can go ahead and tune away but there is only a small amount you can eek out of a 4.0 as it sits.
A different ratio can net more power but I echo again...we're talking about a Wrangler with a 4.0
As far as 6 hp goes...thats being semi-sarcastic which i assumed you'd have known but shame on me for assuming.
Having said that what are you picking up from this tune? 10 hp? 11? You act like 6hp is a personal insult to your tuning acumen.
Hey man to each their own. If I need a significant power increase over the 4.0 I use a different engine.
Rubicon88
TJ Addict
Already been over this....
We are talking about a Jeep with a 4.0 here. You can richen it up if you want but for what gains? 203 horsepower versus 195?
I don't even know where to begin. How about this; the factory tune runs about 11.5:1 at wide open throttle above 3k rpm. Under heavy decel its above 20:1. Varying the a/f ratio isn't just about getting every last hp out of it. There are emmisions, driveability, power, fuel consumption considerations, even. All of those have different optimal air fuel ratios. Different engine load conditions call for different air/fuel ratios not the least of which because your motor can/will go pop if you run it too lean at high rpm and high load where cylinder pressures are highest, and 14.7 is way too lean for WOT. Go ahead and Google it. "Wide open throttle optimal air fuel ratio"
I don't even know why I'm bothering. You don't have any concept of what you are talking about. Rarely have I met someone so completely sure they were right with so obviously no idea what they were talking about. What makes you think an engine always strives for 14.7 under all load conditions? It's like a you heard that number and now think you know everything there is to know on the subject. Your basic premise that 14.7 is the only thing an engine should run at is completely wrong. Google it and see.
I don't even know why I'm bothering. You don't have any concept of what you are talking about. Rarely have I met someone so completely sure they were right with so obviously no idea what they were talking about. What makes you think an engine always strives for 14.7 under all load conditions? It's like a you heard that number and now think you know everything there is to know on the subject. Your basic premise that 14.7 is the only thing an engine should run at is completely wrong. Google it and see.
It's already "richened up" from the factory. Too much in fact. You are suggesting someone might want to tune it richer than 14.7 at wide open throttle to gain 8 more hp over stock. The stock tune is already way richer than 14.7 and in fact a small amount of power can be had by leaning it out to around 12.5-12.8:1. Nothing significant though. The factory did this to protect the motor as do most vehicles. You keep talking like our Jeep motors are some special case. They aren't. You have equally as little of a clue about all engines and how they run, not just the Jeep 4.0
AidenC
TJ Enthusiast
Ok, this thread went down a lot of holes and was interesting to read, but basic question for me is does deleting the 3rd cat or the front two provide noticeable difference power and/or fuel consumption wise? It sounded like the first two are the most restrictive air flow wise, but removing them throws a code. I’m assuming I can keep the upstream O2s to allow the pcm to do its thing as far as air fuel ratio wise, but what gain is there removing rear, pre, or all three. Is 6hp there, 10 hp, 1 hp…or better fuel efficiency…and I’m not a tuner (yet) so not about to get a wideband sensor and try to tune…just curious what benefit there is and how much of a benefit is it really?
Thanks!
What's a Dido?
1. : a mischievous or capricious act : prank, antic. often used in the phrase cut didoes. 2. : something that is frivolous or showy.
If the catalytic converters are in proper working order, there is extremely little restriction. If the catalyst inside starts to flake, chip, break, or foul with carbon, then the restriction can build up and cause power loss anywhere between hardly noticeable to not even letting the engine start.
If compared to a properly functioning catalytic converter, you'd probably get more power running without an air filter than you would deleting the cats.
That said, some aftermarket ones are junk. Personally I use and recommend Magnaflow. They seem to flow as well or perhaps slightly better than stock, and have been very reliable. I did have one that had an issue, but Magnaflow warrantied it.
The exhaust manifold itself might be a better target. If you can get a good tube header (and the catalytic converter assembly) ceramic coated, that helps reduce the heat transferred to the intake, so you can be more aggressive with your timing. Low emissivity Cerakote is what I used on mine (specifically Piston Coat).
ChasUGC
TJ Enthusiast
I thought you’d never ask
On the last one I deleted the third cat, on my current one I am deleting all three cats. Once removed I just use HPTuners to disable the post cat O2 sensors which will make it so it runs great and no CEL or error codes are triggered. I am also installing full long tube headers at the same time.
It’s very easy to remove all the cats, but if you live in a place with emissions or inspections, you won’t pass. We don’t have that here.
I also love the way they smell without cats. Reminds me of my 69 Camaro.
I should also point out that while this is technically illegal, I don’t care what you do or what you don’t do with your Jeep, it is your Jeep after all. Just make sure that you’re aware that you won’t pass emissions or inspections if your state has it.
The 00-06 models are particularly restricted with THREE cats whereas the earlier models only had one.
How about the horrible pollution factor? You said that you could smell it. And that John quote refers to believers and those with faith in Jesus Christ. "In the world", refers to believers, as opposed to people "of this world". They have prevailing values and behaviors of society. Those people would have their cats intact to protect the environment and society from unnecessary pollution, as they have a higher calling from God. No offense intended, just informational background on the bible, which was quoted.
Ok, the reason I was curious was I think I might have a leak around the headers on my stock (engine strickly speaking) 2001, and since I might consider getting new exhaust manifold and headers was curious if at 167k I should consider the cats one way or another…but never meant to bring biblical quotes into it, but yes don’t want to be the cause of global environmental catastrophe either… so will look at the magma flow! I currently have the banks exhaust that I replaced many years ago. Intently still amazed that I get between 15-16 mpgs on 35s going between dc and Michigan through the PA mountains…. Oh and my commuter jeep
Is a 4Xe, and despite the bad press, I love it!
Is a 4Xe, and despite the bad press, I love it!
Ok don’t like stinky…well I did enjoy the bus fumes as a child, so depends what you define as stinky and how much brain damage I acquired lol
I thought you’d never ask
On the last one I deleted the third cat, on my current one I am deleting all three cats. Once removed I just use HPTuners to disable the post cat O2 sensors which will make it so it runs great and no CEL or error codes are triggered. I am also installing full long tube headers at the same time.
It’s very easy to remove all the cats, but if you live in a place with emissions or inspections, you won’t pass. We don’t have that here.
I also love the way they smell without cats. Reminds me of my 69 Camaro.
I should also point out that while this is technically illegal, I don’t care what you do or what you don’t do with your Jeep, it is your Jeep after all. Just make sure that you’re aware that you won’t pass emissions or inspections if your state has it.
The 00-06 models are particularly restricted with THREE cats whereas the earlier models only had one.
Can I do this on my 2002,I have eliminated the 3rd but is yours really loud with all 3 gone?
It was quite loud, yes. You’ll need to figure out something with a resonator to reduce sound.