Cat Overtemp? When to use?
11-14-2003, 06:56 AM
#2
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Whenever you start tuning you should turn it off. You A/F ratio will never hit the desired mixture because it will be too lean and the computer will start dumping extra fuel to cool the cats down
11-14-2003, 08:14 AM
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Originally Posted by HumpinSS
Whenever you start tuning you should turn it off. You A/F ratio will never hit the desired mixture because it will be too lean and the computer will start dumping extra fuel to cool the cats down
if you want to keep some degree of protection. Sustained high output
will just burn them up if you are lean enough (peak power is peak EGT
pretty much). For most people, more than 15 seconds is plenty but if
you were a road racer you might just have to let the cats die. I know
the salt flats guy cooked his.
Wonder about modifying the amount of COT enrichment to where it
brought down EGT, but not as heavily as the (10:1?) target, maybe
to only 12:1. Don't know what the cats' maximum sustained EGT is
and at what exhaust oxygen content but somewhere this info has
to exist. Then you get your EGT vs mixture chart and hope that 10:1
is gross overkill and not what was really necessary all along.
11-14-2003, 10:17 AM
#4
Originally Posted by HumpinSS
Whenever you start tuning you should turn it off. You A/F ratio will never hit the desired mixture because it will be too lean and the computer will start dumping extra fuel to cool the cats down
joel
11-14-2003, 12:15 PM
#5
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Originally Posted by binksz06
Can it (cot) still worm it's way in even if it's set to 'ENABLE= FALSE" with LS1Edit???I'm getting the symptoms with a narrow LSA cam at part throttle 14.5 AFR - but COT is set to False. TIA.
joel
joel
That i am not sure of since i havent verified my A/F ratio with a wide band dyno as yet(iam tuning with the KR sensors). I do know that it richens the hell up outta the mixture to col them down so going from 12.8-13.00 to 10:1 would indicate that it still may be working
11-14-2003, 01:32 PM
#6
Originally Posted by sbrown99TA
Just kind of off the subject, but what is the cat overtemp deal all about? When do you mess with that stuff? Thanks.
sbrown99TA -I'm not trying to hijack this thread. I'm asking info pertinent to COT.....if you disagree, please accept my apologies.
Does the COT work off the O2 Sensors for mixture or is an internal equation based on RPM, MAP (VE) and MAF?
I'm Open loop and no O2 Sensors. Can it still be COT????Thank You.
joel
11-14-2003, 02:29 PM
#7
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I haven't been able to dig up anything authoritative on
the COT algorithm. I've asked before about the "trigger"
but no luck yet. I think it may just be simple time-at-
load. That's the way it's described in the Gen III V8
Engine Management book (they devote a whole three
lines to it on Pg 95).
the COT algorithm. I've asked before about the "trigger"
but no luck yet. I think it may just be simple time-at-
load. That's the way it's described in the Gen III V8
Engine Management book (they devote a whole three
lines to it on Pg 95).
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11-14-2003, 03:01 PM
#8
Originally Posted by jimmyblue
. . . you might just have to let the cats die. I know
the salt flats guy cooked his.
the salt flats guy cooked his.
What I sugest is turning off COTs, taking off the cats and replacing them with off-road pipes, then swaping the cats back on for emissions testing.
11-15-2003, 05:56 PM
#9
heck yeah i did the same thing, take those cats off its not there to help the car. i was told that turning off COT is good for 5-7 rwhp too, dont know if there is truth to this but i was told this was found by dynoing from a friend, so i believe it...
11-15-2003, 10:28 PM
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Let me start off by saying, Scott I like your new avatar. 
Secondly, so does this mean that I should have my tuner turn the COT off on my wife's car? Just recently installed a cam and after a while at idle the car smells so rich it burns the nose.
Secondly, so does this mean that I should have my tuner turn the COT off on my wife's car? Just recently installed a cam and after a while at idle the car smells so rich it burns the nose.
11-15-2003, 10:48 PM
#12
Originally Posted by BriGuy
Let me start off by saying, Scott I like your new avatar.
Secondly, so does this mean that I should have my tuner turn the COT off on my wife's car? Just recently installed a cam and after a while at idle the car smells so rich it burns the nose.
Secondly, so does this mean that I should have my tuner turn the COT off on my wife's car? Just recently installed a cam and after a while at idle the car smells so rich it burns the nose.
A nice Cherry Red glow- the cats under the car!
joel
11-16-2003, 08:56 AM
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COT isn't going to touch idle, it's for high output. The
cats will self-heat when burning off HC/CO but these
are supposed to be small amounts. The tuner should
be fixing the VE map for the cam's overlap effects,
this will bring the mixture into the ballpark.
cats will self-heat when burning off HC/CO but these
are supposed to be small amounts. The tuner should
be fixing the VE map for the cam's overlap effects,
this will bring the mixture into the ballpark.
11-16-2003, 02:39 PM
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Bri, from what I understand if you don't have cats, you should turn COT off. I still have the cats, but metallic ones, so I am unsure what I need done, if anything. Can anyone speak up to whether I am correct or not?
11-16-2003, 03:08 PM
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Originally Posted by purevilss
Bri, from what I understand if you don't have cats, you should turn COT off. I still have the cats, but metallic ones, so I am unsure what I need done, if anything. Can anyone speak up to whether I am correct or not?
I just don't know what the overtemp stuff is actually for, since my car has no cats I've never really messed with it. Thanks.
Steve
