Replacing Main Cat with Cutout - But I have a question
10-18-09, 09:59 AM
#16
The post numbers are listed under "LSD surgery". Not my write up but the best one you will find!
I guess it's the SC300 the has the 4.27 gear that can have a Torsen bolted in. I don't remeber all the details for the needed Torsen unit but I think it has to be a 10 bolt. If you look around on the above thread I'm sure it's mentioned somewhere.
KC
10-19-09, 03:21 PM
#19
fyi for the sensor after the cat is a monitor to make sure for cat efficiency so it will throw the ce.l removal of the o2 sensors means there will be no feed back for the engine to properly control fuel so it will never hit closed loop and run the default map you will lose a bit of mpg and possibly some power but not much to be significant if your going to convert the car to a track car then recommend a wideband o2 sensor and a fuel management system if you have the cash
10-19-09, 05:47 PM
#20
fyi for the sensor after the cat is a monitor to make sure for cat efficiency so it will throw the ce.l removal of the o2 sensors means there will be no feed back for the engine to properly control fuel so it will never hit closed loop and run the default map you will lose a bit of mpg and possibly some power but not much to be significant if your going to convert the car to a track car then recommend a wideband o2 sensor and a fuel management system if you have the cash
Keep in mind this is for OBD1, OBD2 is a different ball game.
Removing the front sensors will make you run, likely, very rich. Will also throw o2 heater codes and possibly throw rich/lean codes. The rear sensors do monitor the cats performance but WILL NOT set a code for missing cats. The only way you'll get a rear o2 sensor code on an OBD1 car is if the o2's heater is bad or disconnected.
It does say, in the repair manual, that the rear sensors help determine the AFR but on my car with no cats, it hasn't caused any issues.
KC
10-19-09, 07:13 PM
#21
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See the thing is... I won't be removing any o2 sensors. I'm just removing the cat and replacing it with a cutout. My only worry was if I had the cutout in the open position (diverting the exhaust out of the cutout), if it would impact the readings on the second o2 sensor (which logically I think it would). If this were the case, then would the second o2 sensor be sending a signal to the ECU to adjust the AFR. If the cutout is in the closed position, it should operate as if the cat was there minus the altering effects that the cat would make on the exhaust gasses.
With the cutout in the open position, I'm guessing that some of the exhaust will be flowing through the rest of the stock piping... and if so...would that be enough to appear "normal" to the second o2 sensor. Does the sensor account for quantity of exhaust passing through or just the quality. If quality, then I don't think it will be impacted that much.
With the cutout in the open position, I'm guessing that some of the exhaust will be flowing through the rest of the stock piping... and if so...would that be enough to appear "normal" to the second o2 sensor. Does the sensor account for quantity of exhaust passing through or just the quality. If quality, then I don't think it will be impacted that much.
10-20-09, 12:42 AM
#22
Yes and no....
Keep in mind this is for OBD1, OBD2 is a different ball game.
Removing the front sensors will make you run, likely, very rich. Will also throw o2 heater codes and possibly throw rich/lean codes. The rear sensors do monitor the cats performance but WILL NOT set a code for missing cats. The only way you'll get a rear o2 sensor code on an OBD1 car is if the o2's heater is bad or disconnected.
It does say, in the repair manual, that the rear sensors help determine the AFR but on my car with no cats, it hasn't caused any issues.
KC
Keep in mind this is for OBD1, OBD2 is a different ball game.
Removing the front sensors will make you run, likely, very rich. Will also throw o2 heater codes and possibly throw rich/lean codes. The rear sensors do monitor the cats performance but WILL NOT set a code for missing cats. The only way you'll get a rear o2 sensor code on an OBD1 car is if the o2's heater is bad or disconnected.
It does say, in the repair manual, that the rear sensors help determine the AFR but on my car with no cats, it hasn't caused any issues.
KC
Last edited by cbrasian; 10-20-09 at 01:08 AM.
10-20-09, 03:44 AM
#23
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I see what you are saying. So I could expect the car to be running a little more rich, but ultimately, I'd be relying on the ECU to be compensating for the change?
10-20-09, 06:03 AM
#24
please read post carefully if you don't understand this i'll try to break it down easier. removal of the o2 sensors will make the comp not go into closed loop... aka limp in mode ob1 and ob2 are different but the feedback is the same...... rear sensor is a monitor it tells the comp to switch lean / rich around stoic so that different portions of exhaust gases are chemically changed by the elements in the cat. In a obd2 car the codes would be for a rich condition not lean on the o2 sensor readouts and the car will be in limp in mode. On a obd 1 car the cel light may or may not turn on. If it is on the car will be dumping gas leading to a richer fuel condition as it is in a limp in mode. The reason is b1s1 and b2s1 checkes the actual afr where as b1s2 is the monitor for the cat so when the exhaust is passing through the three-way catalyst, CO, HC and NO x , the activity of the gas is enhanced under high temperature. As a result, the CO would be oxidized into CO 2 , the HC is turned into H 2 O and CO 2 , and the NO x is deoxidized into nitrogen through the afr switching from lean to rich within stoic and by removal for the cat you will just be dumping fuel as the car will be in a non feedback mode as it cannot go into closed loop.. the recommendation for the wideband and a fuel management system is so that you can control the fuel situation and run it where you want the afr at also the wideband sensor is more accurate as it has a wider range it can sample than a o2 sensor sorry if i'm not more concise with my words but I been running long hours finishing up some project cars
All he wants to do is remove the cats. Removing the cats will not make his car stay in open loop. My car has no cats and does not stay in open loop. I / he can verify this by looking at the VF voltage, which is a feedback value calculated from the front o2 sensors readings.
Also, removing the rear o2's will not prevent closed loop. I have had them unplugged and guess what, the VF voltage still changes and reads like normal which means the ECU is reading and using feedback fromt he VF voltage.
If you need this broken down so you can understand it, google "toyota vf voltage" and maybe you'll learn something new.
KC
10-20-09, 08:18 AM
#25
I simply went in more depth of your post when i refer to o2 sensor i mean b1s1 and b2s1 not b1s2 ,s1b2 i refer to as a monitor...you obviously don't understand what i've stated and frankly I am going to be blunt in saying your attitude plain sucks I explained what i said and you don't understand what i was explaining in the post. I know what i'm talking about...so instead of trying to explain the same thing over and over with misunderstanding. i'm going to leave it here and not post anymore its your attitude "maybe you'll learn something new." that screws this forum up i simply stated i was trying to clear up my post to be understandable if i made it sound confusing..... grow up I'm not your buddy here... you can't just talk to people in that tone have more respect for people. my post is about the toyota vf if you don't get that then leave it for the professionals
Last edited by cbrasian; 10-20-09 at 08:51 AM. Reason: I give up on cl people
10-20-09, 10:09 AM
#26
I thought it was you who started with the attitude and I don't feel I have a bad attitude. I do wonder why you post one thing and then edit the whole post.
Your response shown when I get the thread update email being completely different than what it is when I log on....
Lets both be the better man here and say enough is enough.
Sorry if I offended you, now, back on topic!
No cats will = no problems. Shoot the NOS and let us know how it goes!
KC
Your response shown when I get the thread update email being completely different than what it is when I log on....Lets both be the better man here and say enough is enough.
Sorry if I offended you, now, back on topic!
No cats will = no problems. Shoot the NOS and let us know how it goes!
KC
10-21-09, 03:43 AM
#27
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I appreciate that there are differing viewpoints on the removal of the first set of cats and whether or not it will create any problems.
I guess I am going to have to try it out and monitor it closely. I'm hoping the second o2 sensor is measuring the AFR's in the exhaust and doesn't factor in the quantity of air flowing through the exhaust since that quantity would be reduced with the open cutout.
I guess I am going to have to try it out and monitor it closely. I'm hoping the second o2 sensor is measuring the AFR's in the exhaust and doesn't factor in the quantity of air flowing through the exhaust since that quantity would be reduced with the open cutout.
10-21-09, 04:35 AM
#28
You could try removing both sensors and securing them somewhere in the open air just to see what happens.
Don't forget to keep us updated once you get that thing down the track! I challenge you to do better than my best 1/8 of 7.87! Seriously, I'm always interested to know the track results of different mods be it supercharged, turbo, nos or anything else.
KC
Don't forget to keep us updated once you get that thing down the track! I challenge you to do better than my best 1/8 of 7.87! Seriously, I'm always interested to know the track results of different mods be it supercharged, turbo, nos or anything else.
KC
10-21-09, 05:03 PM
#29
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You could try removing both sensors and securing them somewhere in the open air just to see what happens.
Don't forget to keep us updated once you get that thing down the track! I challenge you to do better than my best 1/8 of 7.87! Seriously, I'm always interested to know the track results of different mods be it supercharged, turbo, nos or anything else.
KC
Don't forget to keep us updated once you get that thing down the track! I challenge you to do better than my best 1/8 of 7.87! Seriously, I'm always interested to know the track results of different mods be it supercharged, turbo, nos or anything else.
KC
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