running lean - Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community

EZWood · 07-29-2013, 08:05 PM

I'm running a catless header and I've been throwing a code p2096, post catalyst fuel trim system too lean bank 1. Any idea of risks for this? I know if its too lean I can blow my motor so I don't want any smart ass answers. I'm looking for actual technical discussion as to what is actually too lean and I will provide logs of Afr commanded and measured with corresponding rpm. Is there anything else I should be logging like load or anything else?

Hardrock4445 · 07-29-2013, 08:17 PM

Did you run any sort of oxygen sensor spacer? I ran into this code too. So I took the spacer out and got po420 code. Long story short: watch your fuel trims. As long as you are +/- 5% from 0 you are fine. However CEL will affect you traction control systems. So spending time with spacers and washers to get the perfect spot in between where you will get lean code from being too far out, or p0420 code from being too close I've got over 7k on my Catless header with no ill effects and fuel trims +\- 5%

EZWood · 07-29-2013, 08:28 PM

Quote:

Originally Posted by Hardrock4445

Did you run any sort of oxygen sensor spacer? I ran into this code too. So I took the spacer out and got po420 code. Long story short: watch your fuel trims. As long as you are +/- 5% from 0 you are fine. However CEL will affect you traction control systems. So spending time with spacers and washers to get the perfect spot in between where you will get lean code from being too far out, or p0420 code from being too close I've got over 7k on my Catless header with no ill effects and fuel trims +\- 5%

I have this weird 90% thing on my downstream sensor that was given to me when I bought the exhaust.

mrk1 · 07-29-2013, 09:06 PM

Basic question, is the car tuned for no cats?

EZWood · 07-29-2013, 09:08 PM

Quote:

Originally Posted by mrk1

Basic question, is the car tuned for no cats?

No tune.

arghx7 · 07-29-2013, 09:27 PM

ECU is not getting an expected rear o2 sensor reading because of the catless header.

The rear o2 sensor is used for the catalyst monitor (which most people are aware of) but it's also used to adjust the reading of the front o2 sensor in cruise operation. It accounts for degradation in the front o2 sensor.

EZWood · 07-29-2013, 10:01 PM

Quote:

Originally Posted by arghx7

ECU is not getting an expected rear o2 sensor reading because of the catless header.

The rear o2 sensor is used for the catalyst monitor (which most people are aware of) but it's also used to adjust the reading of the front o2 sensor in cruise operation. It accounts for degradation in the front o2 sensor.

Which sensor is bank 1 and which is bank 2? If bank 1 is the downstream that explains everything, if bank 1 is the sensor before the cat I'll have some questions. The obvious answer is to have the car tuned, but I have other things that thousand dollars needs to go to, on the other hand if it is running too lean it might be worth it to do a tune first.

mad_sb · 07-29-2013, 10:37 PM

Quote:

Originally Posted by EZWood

Which sensor is bank 1 and which is bank 2? If bank 1 is the downstream that explains everything, if bank 1 is the sensor before the cat I'll have some questions. The obvious answer is to have the car tuned, but I have other things that thousand dollars needs to go to, on the other hand if it is running too lean it might be worth it to do a tune first.

We only have bank 1. Sensor 1 is up stream aka primary O2 aka front sensor aka pre cat. Sensor 2 is downstream aka secondary O2 aka rear sensor aka post cat.

The lean code probably indicates sensor 2 is a bit too far from the stream of exhaust gas or has too small of an opening.

EZWood · 07-30-2013, 12:29 PM

Quote:

Originally Posted by mad_sb

We only have bank 1. Sensor 1 is up stream aka primary O2 aka front sensor aka pre cat. Sensor 2 is downstream aka secondary O2 aka rear sensor aka post cat.

The lean code probably indicates sensor 2 is a bit too far from the stream of exhaust gas or has too small of an opening.

It was too far. I removed the spacer, probably gonna get a running rich code. Thanks for the help.

mad_sb · 07-31-2013, 08:32 AM

Quote:

Originally Posted by EZWood

It was too far. I removed the spacer, probably gonna get a running rich code. Thanks for the help.

or cat inefficiency code P0420. Vibrant sells one you can tweak, it has 3 different orifice inserts IIRC.

HRTROB · 07-31-2013, 02:26 PM

How long were you running the spacer before the code first came up? I've been running an angled o2 sensor on my Borla UEL header for 2,000km now. 2 track days and a lot of highway running with the cruise control on, no CEL so far.

EZWood · 07-31-2013, 02:44 PM

Quote:

Originally Posted by HRTROB

How long were you running the spacer before the code first came up? I've been running an angled o2 sensor on my Borla UEL header for 2,000km now. 2 track days and a lot of highway running with the cruise control on, no CEL so far.

It comes on pretty quick. Could you post a pic of how yours is mounted please?

HRTROB · 07-31-2013, 03:09 PM

Quote:

Originally Posted by EZWood

It comes on pretty quick. Could you post a pic of how yours is mounted please?

Here you go

EZWood · 07-31-2013, 05:21 PM

Quote:

Originally Posted by HRTROB

Here you go

That helps, but do you have a close up so I can determine the angle in relation to the exhaust flow?

07-29-2013, 08:05 PM	#1
EZWood BAMF Join Date: Jun 2012 Drives: 13 fr-s, whiteout, MT. 94 ZJ Location: Apache Junction, Az Posts: 1,007 Thanks: 209 Thanked 345 Times in 215 Posts Mentioned: 13 Post(s) Tagged: 0 Thread(s)	running lean I'm running a catless header and I've been throwing a code p2096, post catalyst fuel trim system too lean bank 1. Any idea of risks for this? I know if its too lean I can blow my motor so I don't want any smart ass answers. I'm looking for actual technical discussion as to what is actually too lean and I will provide logs of Afr commanded and measured with corresponding rpm. Is there anything else I should be logging like load or anything else?

07-29-2013, 08:17 PM	#2
Hardrock4445 Senior Member Join Date: Aug 2012 Drives: 2013 Scion FR-S Location: Syracuse Posts: 719 Thanks: 274 Thanked 277 Times in 161 Posts Mentioned: 6 Post(s) Tagged: 0 Thread(s)	Did you run any sort of oxygen sensor spacer? I ran into this code too. So I took the spacer out and got po420 code. Long story short: watch your fuel trims. As long as you are +/- 5% from 0 you are fine. However CEL will affect you traction control systems. So spending time with spacers and washers to get the perfect spot in between where you will get lean code from being too far out, or p0420 code from being too close I've got over 7k on my Catless header with no ill effects and fuel trims +\- 5% __________________ Mods: Perrin CAI, JDL EL header, DC sports Catless front pipe, top speed auto pro-1 cat-back, H&R sport line springs, Headlight blackout, "Demon eyes"

07-29-2013, 09:06 PM	#4
mrk1 Senior Member Join Date: Mar 2013 Drives: Sterling BRZ Ltd Location: New England Posts: 1,702 Thanks: 403 Thanked 1,389 Times in 671 Posts Mentioned: 20 Post(s) Tagged: 2 Thread(s)	Basic question, is the car tuned for no cats? __________________ The Build Thread GT28RS - eBoost2 - 3.91 Final Drive - Supra LSD

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07-29-2013, 09:27 PM	#6
arghx7 Senior Member Join Date: Nov 2011 Drives: car Location: cold Posts: 599 Thanks: 72 Thanked 607 Times in 185 Posts Mentioned: 33 Post(s) Tagged: 0 Thread(s)	ECU is not getting an expected rear o2 sensor reading because of the catless header. The rear o2 sensor is used for the catalyst monitor (which most people are aware of) but it's also used to adjust the reading of the front o2 sensor in cruise operation. It accounts for degradation in the front o2 sensor.

07-31-2013, 02:26 PM	#11
HRTROB Senior Member Join Date: Dec 2012 Drives: Toyota 86 Location: Manila, Philippines Posts: 457 Thanks: 144 Thanked 271 Times in 140 Posts Mentioned: 13 Post(s) Tagged: 0 Thread(s)	How long were you running the spacer before the code first came up? I've been running an angled o2 sensor on my Borla UEL header for 2,000km now. 2 track days and a lot of highway running with the cruise control on, no CEL so far.

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