SkullV
Veteran CEG'er
Yeah...cryptic post..ill explain when I get home and can scan some dyno graphs tonight.
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Fake converter
- Thread starter z06killinsbf
- Start date
Ian aka jared doesn't ether to me :laugh:
zorrex
Enjoys the Abuse
Thank Kim for that one. I'm still waiting on the explanation of how the presence/absence of cats changes whether your car has the tendency to run rich/lean.
OH very simple.
Your cars pcm regulates many things. So lets just keep or eyes on fuel/air. okay.
Now what we use here on our gasoline cars (only) is a 3 way catalytic converters. 3-way catalytic converters are equipped with a computerized closed-loop feedback fuel injection system employing one or more oxygen sensors. Now when the catalytic converter receives exhaust from an engine running slightly above the stoichiometric point. The cat is not able to perform it's job. When there is more oxygen than required, then the system is said to be running lean. So lets say the cat was removed here. The 02 sensor would signal the pcm instructing it that we are receiving more air then needed. This is when the cat system is in oxidizing state of condition (co and hydrocarbons). This making your pcm adjust your air/fuel ratio increasing fuel to compensate for the increased air. Leaving your car running rich! But at this point there is no going back unless the pcm recognizes a change or Mil eliminators or a new cat is installed!
Now why do these adjustments? If the car knows it's parameters and can run without cats if we never installed them? Thats true...but the car's trying to keep the cats alive by providing the 3 combination gases. IN essence thats what they were designed to work with. As long as the o2 sensor is being satisfied with its readyings then the cat will live longer reducing emissions. Which is what car companies wants. Like the old saying goes....man i hate this emissions crap :laugh:
Now i didn't go into much detail...but you get the jist of things. Back to work.
zorrex
Enjoys the Abuse
I dunno man. I was always under the impression the upper O2's were relevant to air/fuel metering, and the lowers were just cat monitors for emissions purposes.
well you weren't being specific. So i covered the vast majority of cars with cats.
Yes on our cars, the lower o2 sensor just monitors the exhaust gases after the pre-cats.
Now that means the main cat can be removed and nothing would alter the o2 readings. Because there are no o2's after the main cat. Hence why most just buy test pipes or sho-shop pipes without cats. Trubendz sells down pipes without cats. While all companies sell these of road test pipes. They would also include or recomend an o2 eliminator. But they don't.
Unlike msds includes them with its header kit. Because you have to install them. Or just tune them out when you get your tune.
zorrex
Enjoys the Abuse
Well from the start I have been specific with the Contour only. I haven't made any suggestions of any other vehicles as I am not familiar with the design of their cats. I have seen the Duratec cats and I have had discussions and read many discussions about the potential gains for gutting, and I stand by my deduction that gutting the cats will keep you at stock power at best. :shrug:
It'd be nice to see a flow test or dyno runs done, though.
It'd be nice to see a flow test or dyno runs done, though.
I'm glad with your education and years of v6 contour peformance experience...that you can come to that conclusion.
Let me ask you...Since you have seen the Duratec cats and have had discussions and read many discussions about the potential gains for gutting. Please inform me why you stand by your deduction that gutting the cats will keep you at stock power at best.
How much cfm entering the exhaust manifold?
How much is needed before the cat becomes a restriction?
How much cfm does the stock pre-cats flow?
How large is the cat area?
Why install headers?
MSDS gains about 10-17whp gain...is that only because the tubes?
Why didn't msds retain the cat's in their headers if it flows the same?
SkullV
Veteran CEG'er
Due to the fact that gutted/catless pipes flow air better, the upper o2s see readings that they are not used to and they dump fuel to correct, it's the same way that adding a cold air intake to an uncalibrated MAF will make your mixture rich, I have spend countless hours on chassis dyno's with all sorts of vehicles and have seen this time after time after time. My power went out last night so I didn't get a chance to scan the charts I wanted, but I got them all together and I'll scan them today.
zorrex
Enjoys the Abuse
I would like to see fuel trim readings for a car with stock, working cats, compared to a car with gutted cats. I bet you $20 they are nearly the same.
SkullV
Veteran CEG'er
I don't have an x-cal or I would do it for you. I can however show you the Afr readings on a few dyno printouts. Were you interested in STFTs or LTFTs?
zorrex
Enjoys the Abuse
Well I'd think the STFT would be the FT affected, because the flow difference, if it exists, would only be noticed under higher RPM, when the engine is really getting pushed.
Dyoel182
Addicted CEG'er
How hard are you looking?
You know....you honestly are a genius....wtf is the point of installing mil eliminators?
lmao. Dude please stop. Seriously your antics are irregular. I don't know if you have that KNOW IT ALL SYNDROM. But i def think you are one of those that talk out of their arases when they don't know a thing!
1. You ignored my questions. Becuase
A. you can't asnwer them!
B. Cause you don't know how to asnwer them.
C. Because you would look dumb.
SkullV
Veteran CEG'er
AAAAND its gone. LTFT's are what you are going to want to look at. When properly tuned your long term fuel trims will settle in around 2%-3% but closer to 0 would be better. Untuned with intake/exhaust mods you will often see as high as 15%-20%.
SkullV
Veteran CEG'er
The entire purpose of instaling the "o2 sims" in the post cat o2s is to eliminate the check engine code and pass OBD2 emissions. Zorrex is right, the post cat o2s have nothing to do with vehicle performance and only shows cat efficiencey.
striker2
Official CEG Vendor
and that is for every car that has a cat, not just the Contour.
THe rear o2 monitor flow after the said cat. If the mixture is uneven then the computer makes adjustments.
Each bank 02 adjust for each side. IF the upper sensor initial readins are accurate...and lower 2 are off. Then it makes adjustments accordingly.
If the lower o2s read a change...then the car will go either rich or lean. If that occurs then the fuel trims will change based off the o2's readings. Only to prevent the cat from being dmaged even more and keeping the cars emissions within it's area.
When my true duals were installed...the tuner saw my fuel trims and was amazed that my car was running pig rich. 11.5. ON a 2.5L svt engine. So i new then...that the mil eliminators were not doing there job. I removed them and installed cat's. Then i visited the tuner again...and the car went back up to 12.5.
striker2
Official CEG Vendor
no, the PCM never looks at the downstream sensors to determine whether it should adjust the fuel trims. It only looks at them to determine if the the cat(s) is functioning properly. that is the only role of the downstream sensors, nothing else.
IF the cat isn't working properly... what happens then?