O2 fp3 issues
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Stage IV
Joined: Dec 2018
Posts: 4
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From: Florida
O2 fp3 issues
I'm having problems with my tune.
I set my fuel map cruising to 14.25 so could hopefully still be in o2 sensor range. During cruising my target afr reads 14.4-14.5 and my o2s read .8v
I'd like to auto tune to clean things up but the minimum I can target is 14.4 and .8v seems way too rich for the o2 setting in the advanced setup. So basically I'm asking does anyone know why these numbers seem off? 18 fat bob 114 two brothers and heavy breather
I set my fuel map cruising to 14.25 so could hopefully still be in o2 sensor range. During cruising my target afr reads 14.4-14.5 and my o2s read .8v
I'd like to auto tune to clean things up but the minimum I can target is 14.4 and .8v seems way too rich for the o2 setting in the advanced setup. So basically I'm asking does anyone know why these numbers seem off? 18 fat bob 114 two brothers and heavy breather
Club Member
Joined: Dec 2014
Posts: 10,734
Likes: 3,755
From: SWFL
I'm having problems with my tune.
I set my fuel map cruising to 14.25 so could hopefully still be in o2 sensor range. During cruising my target afr reads 14.4-14.5 and my o2s read .8v
I'd like to auto tune to clean things up but the minimum I can target is 14.4 and .8v seems way too rich for the o2 setting in the advanced setup. So basically I'm asking does anyone know why these numbers seem off? 18 fat bob 114 two brothers and heavy breather
I set my fuel map cruising to 14.25 so could hopefully still be in o2 sensor range. During cruising my target afr reads 14.4-14.5 and my o2s read .8v
I'd like to auto tune to clean things up but the minimum I can target is 14.4 and .8v seems way too rich for the o2 setting in the advanced setup. So basically I'm asking does anyone know why these numbers seem off? 18 fat bob 114 two brothers and heavy breather
Road Warrior
Joined: Mar 2012
Posts: 1,514
Likes: 88
From: USA
I'm resurrecting this thread as I've run into a similar issue, and wanted to post what is, hopefully a fix.
On the new exhausts that use the 12mm o2 sensors, they cannot protrude far enough into an aftermarket exhaust when using the 18mm bung adapters. So because of this, you can't properly set up auto tune or even get an accurate AFR reading from the o2 sensor. When using a FP3 the sensor data had the AFR off and voltage high (.8 and higher at times). I could not run auto tune properly or get good sensor data readings.
What I ended up doing was cutting the 12mm o2 sensors and replacing them with 18mm bosch universal 4 wire heated sensors. Part 15733. Note if you do this do not solder the wire, use posi-taps or crimps.
The 18mm sensor can now protrude far enough into the exhaust stream to get a reading.
On the new exhausts that use the 12mm o2 sensors, they cannot protrude far enough into an aftermarket exhaust when using the 18mm bung adapters. So because of this, you can't properly set up auto tune or even get an accurate AFR reading from the o2 sensor. When using a FP3 the sensor data had the AFR off and voltage high (.8 and higher at times). I could not run auto tune properly or get good sensor data readings.
What I ended up doing was cutting the 12mm o2 sensors and replacing them with 18mm bosch universal 4 wire heated sensors. Part 15733. Note if you do this do not solder the wire, use posi-taps or crimps.
The 18mm sensor can now protrude far enough into the exhaust stream to get a reading.
Club Member
Joined: Dec 2014
Posts: 10,734
Likes: 3,755
From: SWFL
I'm resurrecting this thread as I've run into a similar issue, and wanted to post what is, hopefully a fix.
On the new exhausts that use the 12mm o2 sensors, they cannot protrude far enough into an aftermarket exhaust when using the 18mm bung adapters. So because of this, you can't properly set up auto tune or even get an accurate AFR reading from the o2 sensor. When using a FP3 the sensor data had the AFR off and voltage high (.8 and higher at times). I could not run auto tune properly or get good sensor data readings.
What I ended up doing was cutting the 12mm o2 sensors and replacing them with 18mm bosch universal 4 wire heated sensors. Part 15733. Note if you do this do not solder the wire, use posi-taps or crimps.
The 18mm sensor can now protrude far enough into the exhaust stream to get a reading.
On the new exhausts that use the 12mm o2 sensors, they cannot protrude far enough into an aftermarket exhaust when using the 18mm bung adapters. So because of this, you can't properly set up auto tune or even get an accurate AFR reading from the o2 sensor. When using a FP3 the sensor data had the AFR off and voltage high (.8 and higher at times). I could not run auto tune properly or get good sensor data readings.
What I ended up doing was cutting the 12mm o2 sensors and replacing them with 18mm bosch universal 4 wire heated sensors. Part 15733. Note if you do this do not solder the wire, use posi-taps or crimps.
The 18mm sensor can now protrude far enough into the exhaust stream to get a reading.
Interesting you say this, as my S&S pipe uses 18 to 12mm adapters.
Also interesting. Is there a voltage to AFR table we can use to find out target voltage of sensors for a particular reading?
Last edited by Mchad; Apr 29, 2019 at 02:36 PM.
Road Warrior
Joined: Mar 2012
Posts: 1,514
Likes: 88
From: USA
So you are using wide band sensors? Or are these 18mms you got narrow band just like the stock one?
Interesting you say this, as my S&S pipe uses 18 to 12mm adapters.
Also interesting. Is there a voltage to AFR table we can use to find out target voltage of sensors for a particular reading?
Interesting you say this, as my S&S pipe uses 18 to 12mm adapters.
Also interesting. Is there a voltage to AFR table we can use to find out target voltage of sensors for a particular reading?
14.7/1- 0.50
14.6/1- 0.60
14.5/1- 0.70
14.2/1- 0.80
13.5/1- 0.85
13.2/1- 0.90
13.0/1- 0.92
12.5/1- 0.94
12.0/1- 0.95
Last edited by izzyryder; Apr 29, 2019 at 02:58 PM.
Club Member
Joined: Dec 2014
Posts: 10,734
Likes: 3,755
From: SWFL
Very cool. I know what my cruising AFR is set for, per dyno results using a wide band sniffer shoved up the pipe, so I'm interested in seeing how the adapters affect my readings. Thanks!
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Road Warrior
Joined: Mar 2012
Posts: 1,514
Likes: 88
From: USA
what AFR did you set your cruising at? I know 14.4 is pretty much the go-to.. but been playing with 14.4, 14.2....
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Club Member
Joined: Dec 2014
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From: SWFL
Whatever is set by my EPA and warranty compliant HD tuner... :-)
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