running without o2 sensors
Thread Starter
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Seasoned HDF Member
Joined: Oct 2012
Posts: 11,226
Likes: 3,049
From: St.Louis Mo.
running without o2 sensors
was talking to a guy today at the gas station and he said his bike ( 11 heritage) had a stage 1 on it . after looking at it ,it had no o2 sensors and was running a set of python pipes. how can you get by with this ? he did'nt say he had a tuner of any kind. i've heard of this before, just wondering how and why. it's cold here today, but he was out riding.
Extreme HDF Member
Joined: Sep 2010
Posts: 14,744
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From: Phoenix '53, '88, '09 Big Twins
some of the old power commander and other stuff doesn;t use o2 sensors.
but then the ecm doesn;t know if the motor is running rich or lean or when- so it can ONLY do what the map loaded into it says.
because a lean motor will destroy itself, many of these maps are written to be overly rich.
you may have ridden behind these guys, you can smell it.
an overly rich mixture makes LESS power, and will carbon up the combustion chamber.
I stayed away from the EFI on H-D's until they finally added o2 sensorss...buell had 'em long before H-D did.
Mike
but then the ecm doesn;t know if the motor is running rich or lean or when- so it can ONLY do what the map loaded into it says.
because a lean motor will destroy itself, many of these maps are written to be overly rich.
you may have ridden behind these guys, you can smell it.
an overly rich mixture makes LESS power, and will carbon up the combustion chamber.
I stayed away from the EFI on H-D's until they finally added o2 sensorss...buell had 'em long before H-D did.
Mike
Thread Starter
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Seasoned HDF Member
Joined: Oct 2012
Posts: 11,226
Likes: 3,049
From: St.Louis Mo.
he did have plugs in the pipes where the sensors should be. he said he had the work done at a dealer and sounded as if he didn't know what they did. but as i said before he said just a stage 1 . this is what i thought also you had to have a tuner to run without the o2's. learn more about these fuelie bikes everyday.
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Road Master
Joined: Dec 2010
Posts: 1,049
Likes: 264
From: Fresno Ca
My power commander came with plugs for the harnesses to complete the circuit and fool the computer into thinking the sensors were plugged in.
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Road Master
Joined: Jul 2010
Posts: 784
Likes: 56
From: Eastern Iowa
Same deal with my Power Commander 3.
Disconnected O2 sensors and resistor plugs to complete the circuit.
All per the instruction and parts provided from PC.
Road Warrior
Joined: Feb 2009
Posts: 1,274
Likes: 130
From: Now Western TN
Your friends bike is running in an open loop configuration. That means the the ECM is not using the o2 sensors to make slight adjustments based on the sensors. The stock bikes come with narrow band sensors that are basically only good for sensing changes in the cruising range and when using these the bike would be running in a closed loop configuration.
I disagree with mkguitar, running open loop doesn't mean the bike is running too rich. I run my tune with an AFR at 14.2 in the cruising range where the narrow band sensors would be used. This AFR value tells the ECM that it is in an open loop configuration but this is not too rich, in fact the standard AFR for closed loop (STOIC) is only slightly higher at 14.62. This is the factory setting and IMHO is too lean for these bikes. mkguitar probably has experience with some people running the AFR's down in the 13's in the cruising range, but it really depends on the bike set up (Stage I or more work done like heads and cams).
Older tuners needed the wire (resistor) jumpers put in the connector of the o2 plugs, but newer tuners can set the ECM to disable the sensors so the jumpers are not needed. Example the Power commander V (PCV) needed them, the Power Vision doesn't.
I disagree with mkguitar, running open loop doesn't mean the bike is running too rich. I run my tune with an AFR at 14.2 in the cruising range where the narrow band sensors would be used. This AFR value tells the ECM that it is in an open loop configuration but this is not too rich, in fact the standard AFR for closed loop (STOIC) is only slightly higher at 14.62. This is the factory setting and IMHO is too lean for these bikes. mkguitar probably has experience with some people running the AFR's down in the 13's in the cruising range, but it really depends on the bike set up (Stage I or more work done like heads and cams).
Older tuners needed the wire (resistor) jumpers put in the connector of the o2 plugs, but newer tuners can set the ECM to disable the sensors so the jumpers are not needed. Example the Power commander V (PCV) needed them, the Power Vision doesn't.
Last edited by Bowhunter61; Nov 27, 2016 at 07:42 AM.