Where are my CEL's??????
Thread Starter
Safety Car
Joined: Feb 2007
Posts: 4,939
Likes: 448
From: CHOCOWINITY NC
Where are my CEL's??????
200 miles now on my catted LG Long Tube install and NO check engine light yet. HP Tuners just arrived so I'm all set to turn off the offending codes, but curious why it hasn't thrown one yet...('08, LS3).....Lucky? Smarter '08 ECU?
Last edited by Modshack; Dec 3, 2007 at 03:30 PM.
Team Owner
Joined: May 2002
Posts: 26,900
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From: Bann Camp & N.Y.C.
St. Jude Donor '08
all cleared/shut off now
Racer
Joined: Dec 2006
Posts: 343
Likes: 1
From: Houston TX
check under pending codes and I bet you will find it. The problem has to persist for a while before they come on. I clocked over 500 miles before mine came on in my 07 with kooks. It showed up in pending codes after the 2nd day.
Thread Starter
Safety Car
Joined: Feb 2007
Posts: 4,939
Likes: 448
From: CHOCOWINITY NC
Thanks!...
Team Owner
Joined: Aug 2006
Posts: 57,804
Likes: 1
From: Portrichey FL
St. Jude Donor '13
Tech Contributor
Joined: Jul 2002
Posts: 14,950
Likes: 264
From: St. Louis, MO
St. Jude Donor '08
The P0420 and 430 codes have a specific driving/condition test that needs to be met then the tests will run and likely fail. Mine did it at the same place on my daily drive every day. Reset in the morning, light on at the same exit ramp every afternoon. In my case it happened after my 2 mile highway drive almost every day.
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Drifting
Joined: Nov 2004
Posts: 1,923
Likes: 62
From: California
High flow cats are 2-way (not OBD II compliant), not 3-way like the factory cats. Your 02 sensors will pick them up sooner or later. Unless you get it tuned-out your CEL is on his way, just taking his sweet time.
Last edited by DJackman; Dec 5, 2007 at 12:37 PM.
Tech Contributor
Joined: Mar 2003
Posts: 12,094
Likes: 197
From: Colorado Springs, CO
St. Jude Donor '08-'09-'10-'11
I almost got nausia from all your deleted codes.
I have:
L92 heads
A ported L75 manifold
cam
Air cleaner swap
Lg headers
ported TB
4.10's
N2O
UD pulley
modded MAF
the list I'm sure goes on but the point is that with a proper tune and all my mods I didnt have to delete a single code for CEL's. All of those codes are there for a reason.
Maybe if the tune was proper you wouldnt need to.
As to why you get the CEL in the first place: The car monitors the fuel trends lean or rich and they swing back and forth as the O2's correct. The range they can correct for is limited. When a car is tuned properly especially for a VE tune, the car should be at zero for the long term fuel trend. That means neutral. When I tune relatively stock cars they tend to run with positive fuel trends. That mean that if the car wasnt correcting with O2 sensors it would be lean. The range is can compensate for is +24 to -15 or so. So if it gets more than 24% lean the car cant compensate and you actually do run lean which runs hotter and thus makes the O2's read that and it tirggers a lean code and a CEL. When you put on headers it leans you out at part throttle even more than stock. An air cleaner even more. The result is it comes close or over the +24% and triggers the CEL for some while others get a +23 and it doenst trigger. When a basic tune is done the car will run nominally at zero or non-positive most of the time but if the VE table isnt tuned there often is a place wher the car can run lean at part throttle under certain loads. When scanning on the hiway you may see +11 at 3500rpm in 3rd and +2 at 2300 in 5th while it may be zero in oher places. My point is that they have to be tuned properly. Turning them off is what a bad tuner does to not have to tune the VE table. There are conditions such as car damaging one that require the CEL intact or possible. Once that is done you will always be a zero Long Term Fuel Trends no matter what load and rpm....thus no lean codes or cat light off issues.
I have:
L92 heads
A ported L75 manifold
cam
Air cleaner swap
Lg headers
ported TB
4.10's
N2O
UD pulley
modded MAF
the list I'm sure goes on but the point is that with a proper tune and all my mods I didnt have to delete a single code for CEL's. All of those codes are there for a reason.
Maybe if the tune was proper you wouldnt need to.
As to why you get the CEL in the first place: The car monitors the fuel trends lean or rich and they swing back and forth as the O2's correct. The range they can correct for is limited. When a car is tuned properly especially for a VE tune, the car should be at zero for the long term fuel trend. That means neutral. When I tune relatively stock cars they tend to run with positive fuel trends. That mean that if the car wasnt correcting with O2 sensors it would be lean. The range is can compensate for is +24 to -15 or so. So if it gets more than 24% lean the car cant compensate and you actually do run lean which runs hotter and thus makes the O2's read that and it tirggers a lean code and a CEL. When you put on headers it leans you out at part throttle even more than stock. An air cleaner even more. The result is it comes close or over the +24% and triggers the CEL for some while others get a +23 and it doenst trigger. When a basic tune is done the car will run nominally at zero or non-positive most of the time but if the VE table isnt tuned there often is a place wher the car can run lean at part throttle under certain loads. When scanning on the hiway you may see +11 at 3500rpm in 3rd and +2 at 2300 in 5th while it may be zero in oher places. My point is that they have to be tuned properly. Turning them off is what a bad tuner does to not have to tune the VE table. There are conditions such as car damaging one that require the CEL intact or possible. Once that is done you will always be a zero Long Term Fuel Trends no matter what load and rpm....thus no lean codes or cat light off issues.
Last edited by SpinMonster; Dec 5, 2007 at 12:52 PM.
Melting Slicks
Joined: Feb 2006
Posts: 2,007
Likes: 1
From: Eastern PA:ECS Paxton Novi 1500(676rwhp,585tq on stock engine),LG headers, 410's, Corsa Sports, ECS Alky Kit
St. Jude Donor '08-'09
I almost got nausia from all your deleted codes.
I have:
L92 heads
A ported L75 manifold
cam
Air cleaner swap
Lg headers
ported TB
4.10's
N2O
UD pulley
modded MAF
the list I'm sure goes on but the point is that with a proper tune and all my mods I didnt have to delete a single code for CEL's. All of those codes are there for a reason.
Maybe if the tune was proper you wouldnt need to.
As to why you get the CEL in the first place: The car monitors the fuel trends lean or rich and they swing back and forth as the O2's correct. The range they can correct for is limited. When a car is tuned properly especially for a VE tune, the car should be at zero for the long term fuel trend. That means neutral. When I tune relatively stock cars they tend to run with positive fuel trends. That mean that if the car wasnt correcting with O2 sensors it would be lean. The range is can compensate for is +24 to -15 or so. So if it gets more than 24% lean the car cant compensate and you actually do run lean which runs hotter and thus makes the O2's read that and it tirggers a lean code and a CEL. When you put on headers it leans you out at part throttle even more than stock. An air cleaner even more. The result is it comes close or over the +24% and triggers the CEL for some while others get a +23 and it doenst trigger. When a basic tune is done the car will run nominally at zero or non-positive most of the time but if the VE table isnt tuned there often is a place wher the car can run lean at part throttle under certain loads. When scanning on the hiway you may see +11 at 3500rpm in 3rd and +2 at 2300 in 5th while it may be zero in oher places. My point is that they have to be tuned properly. Turning them off is what a bad tuner does to not have to tune the VE table. There are conditions such as car damaging one that require the CEL intact or possible. Once that is done you will always be a zero Long Term Fuel Trends no matter what load and rpm....thus no lean codes or cat light off issues.
I have:
L92 heads
A ported L75 manifold
cam
Air cleaner swap
Lg headers
ported TB
4.10's
N2O
UD pulley
modded MAF
the list I'm sure goes on but the point is that with a proper tune and all my mods I didnt have to delete a single code for CEL's. All of those codes are there for a reason.
Maybe if the tune was proper you wouldnt need to.
As to why you get the CEL in the first place: The car monitors the fuel trends lean or rich and they swing back and forth as the O2's correct. The range they can correct for is limited. When a car is tuned properly especially for a VE tune, the car should be at zero for the long term fuel trend. That means neutral. When I tune relatively stock cars they tend to run with positive fuel trends. That mean that if the car wasnt correcting with O2 sensors it would be lean. The range is can compensate for is +24 to -15 or so. So if it gets more than 24% lean the car cant compensate and you actually do run lean which runs hotter and thus makes the O2's read that and it tirggers a lean code and a CEL. When you put on headers it leans you out at part throttle even more than stock. An air cleaner even more. The result is it comes close or over the +24% and triggers the CEL for some while others get a +23 and it doenst trigger. When a basic tune is done the car will run nominally at zero or non-positive most of the time but if the VE table isnt tuned there often is a place wher the car can run lean at part throttle under certain loads. When scanning on the hiway you may see +11 at 3500rpm in 3rd and +2 at 2300 in 5th while it may be zero in oher places. My point is that they have to be tuned properly. Turning them off is what a bad tuner does to not have to tune the VE table. There are conditions such as car damaging one that require the CEL intact or possible. Once that is done you will always be a zero Long Term Fuel Trends no matter what load and rpm....thus no lean codes or cat light off issues.
Spin are you running the rear O2's on your cats?
Racer
Joined: Dec 2006
Posts: 343
Likes: 1
From: Houston TX
I almost got nausia from all your deleted codes.
I have:
L92 heads
A ported L75 manifold
cam
Air cleaner swap
Lg headers
ported TB
4.10's
N2O
UD pulley
modded MAF
the list I'm sure goes on but the point is that with a proper tune and all my mods I didnt have to delete a single code for CEL's. All of those codes are there for a reason.
Maybe if the tune was proper you wouldnt need to.
As to why you get the CEL in the first place: The car monitors the fuel trends lean or rich and they swing back and forth as the O2's correct. The range they can correct for is limited. When a car is tuned properly especially for a VE tune, the car should be at zero for the long term fuel trend. That means neutral. When I tune relatively stock cars they tend to run with positive fuel trends. That mean that if the car wasnt correcting with O2 sensors it would be lean. The range is can compensate for is +24 to -15 or so. So if it gets more than 24% lean the car cant compensate and you actually do run lean which runs hotter and thus makes the O2's read that and it tirggers a lean code and a CEL. When you put on headers it leans you out at part throttle even more than stock. An air cleaner even more. The result is it comes close or over the +24% and triggers the CEL for some while others get a +23 and it doenst trigger. When a basic tune is done the car will run nominally at zero or non-positive most of the time but if the VE table isnt tuned there often is a place wher the car can run lean at part throttle under certain loads. When scanning on the hiway you may see +11 at 3500rpm in 3rd and +2 at 2300 in 5th while it may be zero in oher places. My point is that they have to be tuned properly. Turning them off is what a bad tuner does to not have to tune the VE table. There are conditions such as car damaging one that require the CEL intact or possible. Once that is done you will always be a zero Long Term Fuel Trends no matter what load and rpm....thus no lean codes or cat light off issues.
I have:
L92 heads
A ported L75 manifold
cam
Air cleaner swap
Lg headers
ported TB
4.10's
N2O
UD pulley
modded MAF
the list I'm sure goes on but the point is that with a proper tune and all my mods I didnt have to delete a single code for CEL's. All of those codes are there for a reason.
Maybe if the tune was proper you wouldnt need to.
As to why you get the CEL in the first place: The car monitors the fuel trends lean or rich and they swing back and forth as the O2's correct. The range they can correct for is limited. When a car is tuned properly especially for a VE tune, the car should be at zero for the long term fuel trend. That means neutral. When I tune relatively stock cars they tend to run with positive fuel trends. That mean that if the car wasnt correcting with O2 sensors it would be lean. The range is can compensate for is +24 to -15 or so. So if it gets more than 24% lean the car cant compensate and you actually do run lean which runs hotter and thus makes the O2's read that and it tirggers a lean code and a CEL. When you put on headers it leans you out at part throttle even more than stock. An air cleaner even more. The result is it comes close or over the +24% and triggers the CEL for some while others get a +23 and it doenst trigger. When a basic tune is done the car will run nominally at zero or non-positive most of the time but if the VE table isnt tuned there often is a place wher the car can run lean at part throttle under certain loads. When scanning on the hiway you may see +11 at 3500rpm in 3rd and +2 at 2300 in 5th while it may be zero in oher places. My point is that they have to be tuned properly. Turning them off is what a bad tuner does to not have to tune the VE table. There are conditions such as car damaging one that require the CEL intact or possible. Once that is done you will always be a zero Long Term Fuel Trends no matter what load and rpm....thus no lean codes or cat light off issues.
Tech Contributor
Joined: Jul 2002
Posts: 14,950
Likes: 264
From: St. Louis, MO
St. Jude Donor '08
Do a google search for p0420 test parameters and you'll find the answer. I'm posting from iPhone or would paste up.
Front O2 sensors switch from lean to rich in normal operation. Basically the rear O2 lean to rich switching frequency is compared to a weighted average switching of the front O2's and if the rears are switching too fast then it indicates the cars aren't storing enough oxygen so the code of inefficient cats is set. Apparently new high efficiency cats will store enough O2 to make the rears switch hardly at all in closed loop. It can take a few drive cycles to get enough information to make the calculation.
Front O2 sensors switch from lean to rich in normal operation. Basically the rear O2 lean to rich switching frequency is compared to a weighted average switching of the front O2's and if the rears are switching too fast then it indicates the cars aren't storing enough oxygen so the code of inefficient cats is set. Apparently new high efficiency cats will store enough O2 to make the rears switch hardly at all in closed loop. It can take a few drive cycles to get enough information to make the calculation.
Safety Car
Joined: Dec 2004
Posts: 3,565
Likes: 5
From: stafford country, va. Avatar: Me on turn 3 @ Bristol (The World's Fastest Half-Mile)
...the list I'm sure goes on but the point is that with a proper tune and all my mods I didnt have to delete a single code for CEL's. All of those codes are there for a reason.
... My point is that they have to be tuned properly. Turning them off is what a bad tuner does to not have to tune the VE table. There are conditions such as car damaging one that require the CEL intact or possible. ...
... My point is that they have to be tuned properly. Turning them off is what a bad tuner does to not have to tune the VE table. There are conditions such as car damaging one that require the CEL intact or possible. ...
underlines added for emphasis.
the before and after cat o2 sensors are compared to each other to determine cat efficiency.
Thread Starter
Safety Car
Joined: Feb 2007
Posts: 4,939
Likes: 448
From: CHOCOWINITY NC
I should have known by starting this thread that they were right around the corner! CAT Low efficiency Codes popped up today at the 250 mile mark. Turned em off with HP tuners and all is good with the world.. Thanks for all the feedback. Also from my first scan, LTFT's and STFT's are right in line........(-3% on LFTF)
Last edited by Modshack; Dec 6, 2007 at 02:22 PM.
Tech Contributor
Joined: Mar 2003
Posts: 12,094
Likes: 197
From: Colorado Springs, CO
St. Jude Donor '08-'09-'10-'11
Tech Contributor
Joined: Mar 2003
Posts: 12,094
Likes: 197
From: Colorado Springs, CO
St. Jude Donor '08-'09-'10-'11
The standard 420/430 code is set by the rear o2's. There only function is to ensure catalyst efficiency. The fuel enrichment is controled by the front o2's. Moving them back may have an effect on their accuracy, but I highly doubt the effect would be substantial enough to cause the o2's to go out of range.
Running that positive in closed loop causes the car too be too rich at WOT which is the source for insufficient light off. Hence the codes some cant get rid of.
Tech Contributor
Joined: Mar 2003
Posts: 12,094
Likes: 197
From: Colorado Springs, CO
St. Jude Donor '08-'09-'10-'11
I should have known by starting this thread that they were right around the corner! CAT Low efficiency Codes popped up today at the 250 mile mark. Turned em off with HP tuners and all is good with the world.. Thanks for all the feedback. Also from my first scan, LTFT's and STFT's are right in line........(-3% on LFTF)The scan needs to have cruise at 45mph in as many gears as you can sustained for at least 20 seconds each.....a little less high in speed is ok and understandable. Include a short idle.