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Old Oct 14, 2015 | 12:26 AM
  #16  
RSTHD150's Avatar
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Joined: Nov 2014
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From: Antelope Valley
Originally Posted by glc
No, it trips a CEL for low cat efficiency on THESE engines.
here is what is going to happen.

you replace the stock catalytic converters with hfc's (high flow cats)

your tear your exhaust apart and lets say you put spacers in the rear sensor(which was a popular fix on other vehicles but problem still persists) your vehicle will still be out of tune because there is less of a filter or secondary gasses. there is less o2 in the system so the vehicle will still try to lean out the engine. NO MATTER WHAT MAKE OR MODEL THIS WILL HAPPEN. Its all part of the OBD-II system in every car.

the purpose of the OBD-II system is to adjust the vehicle on the fly without having to stop or restart the car. sometimes it makes changes 5 to 7 times a second dependent on the application, much like you should have read on the previous link that I provided. this helps the vehicle run at its most efficient state for elevation, humididty, speed, temperature etc.

you can get away with basic modifications to a vehicle like less restrictive muffler or what is known as a catback system, a more efficient intake, lightweight pulleys etc. because the onboard diagnostic system will trim or add fuel as needed. when you remove a part of the OBD-II or change it, the vehicle will try to correct itself, if it cant THEN IT THROWS A CEL.

hope that this information might help, I know a lot of my responses have been a little short. I do know what I'm talking about because I have lived it. I support modding in most ways, its up to you how you would want to mod. I wouldn't want to burn up $8000 if I didnt' have to, and this knowledge hopefully will help prevent that.
 
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Old Oct 19, 2015 | 11:04 PM
  #17  
Galaxy's Avatar
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So go with the Maggy cat that has the bung in it for the aft O2 and orient it so that the bung is downstream of the direction of flow. When you go to the magnaflow site, I can't figure out how to search for universal cats unless you search by particular part number. i know they have a few different lengths...how do you pick which length is best to go with? For example, the popular one around here seems to be the 94136. It has an O2 bung and 13" long. The 94166 is pretty much the same converter with an O2 bung, but it's 16" long. What difference would that make if any at all?
 

Last edited by Galaxy; Oct 19, 2015 at 11:13 PM.
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Old Oct 25, 2015 | 08:01 PM
  #18  
DarrenWS6's Avatar
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Joined: Mar 2008
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From: Mansfield, P.A.
Originally Posted by RSTHD150
here is what is going to happen.

you replace the stock catalytic converters with hfc's (high flow cats)

your tear your exhaust apart and lets say you put spacers in the rear sensor(which was a popular fix on other vehicles but problem still persists) your vehicle will still be out of tune because there is less of a filter or secondary gasses. there is less o2 in the system so the vehicle will still try to lean out the engine. NO MATTER WHAT MAKE OR MODEL THIS WILL HAPPEN. Its all part of the OBD-II system in every car.

the purpose of the OBD-II system is to adjust the vehicle on the fly without having to stop or restart the car. sometimes it makes changes 5 to 7 times a second dependent on the application, much like you should have read on the previous link that I provided. this helps the vehicle run at its most efficient state for elevation, humididty, speed, temperature etc.

you can get away with basic modifications to a vehicle like less restrictive muffler or what is known as a catback system, a more efficient intake, lightweight pulleys etc. because the onboard diagnostic system will trim or add fuel as needed. when you remove a part of the OBD-II or change it, the vehicle will try to correct itself, if it cant THEN IT THROWS A CEL.

hope that this information might help, I know a lot of my responses have been a little short. I do know what I'm talking about because I have lived it. I support modding in most ways, its up to you how you would want to mod. I wouldn't want to burn up $8000 if I didnt' have to, and this knowledge hopefully will help prevent that.
I get what you are saying. The shorter converters on each bank with less of a cell count than the much higher cell count OEMs will cause the vehicle to run poorer without finalized air/fuel ratio adjustment rather than letting the truck's computer 'learn' the setup itself. The newer cats will outflow the OEM units, causing a drop in the A:F ratio that the computer may not be able to make up for completely. Such as in V8 sports cars, off road Y pipes/X pipes are a popular thing, but run best after custom tuning for the setup.

I'm not 100% on it, but I can understand the point. A tuned vehicle is a happier vehicle most often. This would be an excellent question for a custom tuner file specialist.
 
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Old Oct 25, 2015 | 10:47 PM
  #19  
RSTHD150's Avatar
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Joined: Nov 2014
Posts: 241
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From: Antelope Valley
Call stillen motor sports. Ask to talk to Sam, he tuned my 370z a couple years back. He will tell you the same thing.
 
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