Heat Issue
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Cruiser
Joined: Jul 2007
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Heat Issue
I know there's bee a ton of posts on the infamous "heat issues" of the 07"s. Here is an interesting article that adresses root cause:
The 2007 engines have a reputation for very hot exhaust systems. This problem is well documented for the 2007 FLH's, but does exist on all the bikes. All these bikes including the 2006 Dyna's are also know to have high operating temperatures and poor throttle response while cruising. This issue is directly related to the EFI closed loop operation mode at idle and cruising speeds. In closed loop mode, the narrow band O2 sensors used by the Delphi ECU hold the air fuel ratio at 14.7:1 which is good for EPA compliant emissions but creates a very hot exhaust pipe. Nightrider has a fix for this issue that will reduce the exhaust temperature, improve throttle response and increase HP.
LC1 Wide Band O2 Sensor Upgrade for 2007/2008 HD Engines
What are the issues with the 2007 HD engine?
Right after the 2007 HD motorcycles were introduced the issue of high engine heat and poor throttle response showed up. Nightrider with its background and experience in fuel injection systems was able to quickly identify the HD supplied narrow band O2 sensors and the OEM EFI operating in closed loop mode as a significant source of the complaints. Even Harley-Davidson recognized that there was an issue and put out an EFI download to improve the situation for FLH's. But this HD supplied upgrade did little to address the real cause of the issue. Harley-Davidson was unable to do much more than it did for the FLH's because of Government EPA regulations and most Dealers had little idea what the real problem was or how to correct it. The most common fix "sold" to riders was a Stage 1 download, SE Race Tuner or installing a PowerCommander or similar "black box" upgrades. None of these upgrades was overly successful at reducing temperature because they never addressed the real cause of the situation which is the ECU operating in closed loop mode. Eventually some of the "black box" aftermarket companies started supplying O2 Eliminators for the 2007 bikes. The O2 eliminators would reduce the heat, but most riders saw large drops in fuel mileage. When the O2 sensor is disconnected from the EFI, the engine is forced to run at an overly rich 12:1 fuel ratio in many circumstances. This is an overly rich fuel mixture that drops gas mileage and can result in excessive carbon buildup in the engine.
Can the situation be fixed?
What was needed is a Wide Band O2 sensor upgrade for the 07 HD's that would allow the rider or mechanic to set an appropriate AFR for the engine and the way it is ridden. Under most circumstances, the more appropriate AFR is in the 13.5-13.0:1 range. This AFR helps keep engines cooler, provides good throttle response and does not severely impact gas mileage.
Without getting into the heavy technical details, replacing narrow band O2 sensors with a wide band O2 sensor is a lot more complex than just taking the NBO2 out of the exhaust and installing the WBO2 sensor. Narrow band O2 sensor basically only understand a single AFR, 14.7:1. This is a good AFR for gas mileage and water cooled engines. But 14.7:1 AFR produces the highest exhaust temperatures, which is not good for air cooled engines or motorcycles. A Wide Band sensor is able to accurately report on air fuel ratios from 10:1 to 20:1. This makes them ideal for performance and pollution controlled engines. But wide band sensors require special electronic circuitry to process the signals from the sensor and they also produce different voltages than the NBO2 sensor. A narrow band O2 sensor puts out a signal of 0-1 Volts where the wide band sensor electronics puts out a signal of 0-5 Volts, making it seem incompatible with the Delphi ECU.
But this incompatibility between WBO2 and NBO2 sensors can be overcome with some additional electronics. Nightrider identified and succe
The 2007 engines have a reputation for very hot exhaust systems. This problem is well documented for the 2007 FLH's, but does exist on all the bikes. All these bikes including the 2006 Dyna's are also know to have high operating temperatures and poor throttle response while cruising. This issue is directly related to the EFI closed loop operation mode at idle and cruising speeds. In closed loop mode, the narrow band O2 sensors used by the Delphi ECU hold the air fuel ratio at 14.7:1 which is good for EPA compliant emissions but creates a very hot exhaust pipe. Nightrider has a fix for this issue that will reduce the exhaust temperature, improve throttle response and increase HP.
LC1 Wide Band O2 Sensor Upgrade for 2007/2008 HD Engines
What are the issues with the 2007 HD engine?
Right after the 2007 HD motorcycles were introduced the issue of high engine heat and poor throttle response showed up. Nightrider with its background and experience in fuel injection systems was able to quickly identify the HD supplied narrow band O2 sensors and the OEM EFI operating in closed loop mode as a significant source of the complaints. Even Harley-Davidson recognized that there was an issue and put out an EFI download to improve the situation for FLH's. But this HD supplied upgrade did little to address the real cause of the issue. Harley-Davidson was unable to do much more than it did for the FLH's because of Government EPA regulations and most Dealers had little idea what the real problem was or how to correct it. The most common fix "sold" to riders was a Stage 1 download, SE Race Tuner or installing a PowerCommander or similar "black box" upgrades. None of these upgrades was overly successful at reducing temperature because they never addressed the real cause of the situation which is the ECU operating in closed loop mode. Eventually some of the "black box" aftermarket companies started supplying O2 Eliminators for the 2007 bikes. The O2 eliminators would reduce the heat, but most riders saw large drops in fuel mileage. When the O2 sensor is disconnected from the EFI, the engine is forced to run at an overly rich 12:1 fuel ratio in many circumstances. This is an overly rich fuel mixture that drops gas mileage and can result in excessive carbon buildup in the engine.
Can the situation be fixed?
What was needed is a Wide Band O2 sensor upgrade for the 07 HD's that would allow the rider or mechanic to set an appropriate AFR for the engine and the way it is ridden. Under most circumstances, the more appropriate AFR is in the 13.5-13.0:1 range. This AFR helps keep engines cooler, provides good throttle response and does not severely impact gas mileage.
Without getting into the heavy technical details, replacing narrow band O2 sensors with a wide band O2 sensor is a lot more complex than just taking the NBO2 out of the exhaust and installing the WBO2 sensor. Narrow band O2 sensor basically only understand a single AFR, 14.7:1. This is a good AFR for gas mileage and water cooled engines. But 14.7:1 AFR produces the highest exhaust temperatures, which is not good for air cooled engines or motorcycles. A Wide Band sensor is able to accurately report on air fuel ratios from 10:1 to 20:1. This makes them ideal for performance and pollution controlled engines. But wide band sensors require special electronic circuitry to process the signals from the sensor and they also produce different voltages than the NBO2 sensor. A narrow band O2 sensor puts out a signal of 0-1 Volts where the wide band sensor electronics puts out a signal of 0-5 Volts, making it seem incompatible with the Delphi ECU.
But this incompatibility between WBO2 and NBO2 sensors can be overcome with some additional electronics. Nightrider identified and succe
Extreme HDF Member
Joined: Apr 2006
Posts: 10,449
Likes: 46
From: Roswell, GA
RE: Heat Issue
It shouldn't take so many words to say that the HD ECM for '07 and newer bikes have very lean a/f settings to achieve EPA compliance that '06 and older touring bikes don't have--of course, simply explaining the cause for the condition would defeat the purpose of making the sales pitch.
