Haltech E6X Manual DOS Version - Manual (Page 86)

E6X Manual
86
sensor. If the closed loop function is responding erratically, constantly overdriving to
the adjustment limits, or if there is insufficient oscillation in the air-fuel ratio for the
catalytic converter to operate, increasing this parameter may help. If it is set too high,
the feedback loop will be noticeably slow to respond to change.
O2 Sensor Threshold Voltage
This is the sensor voltage by which the E6X determines whether the engine is lean or
rich; it is the target that is sought to be maintained. This is normally set to the voltage
that corresponds to an air-fuel ratio of 14.7:1, the NGK heated 4-wire sensor threshold
voltage is around 600mV this value will vary for different sensors. It is also known as
the sensors reference voltage.
Maximum Fuel Increase
The closed loop algorithm will be permitted to increase the fuel injection time no
further than this limit while attempting to enrich the mixture. The valid range for this
limit is 5% to 12.5%.
Maximum Fuel Decrease
Again a range of 5% to 12.5% applies to this parameter which is the limit of correction
permitted to the base fuel injection time when leaning the mix.
Note: It is preferable to keep the increase and decrease limits small (say around
5-10%). Excessive swinging of the air-fuel ratio can result in surging and poor
operation of the catalytic converter. The closed loop algorithm should never be
used as means to correct bad mapping.
Engine Cycles at Idle
Exhaust gas transportation time is much higher at idle, when the engine is breathing
the least. If running the closed loop at idle, a longer time must be allowed to pass
before performing a feedback correction response.
O2 Sensor Threshold at Idle
It is unlikely that the engine will run at idle smoothly at the same air-fuel ratio as at
cruise. Typically, a richer mix is necessary. This parameter allows a different
threshold voltage to be targeted during closed loop correction at idle.
O2 Sensor Type
The type of sensor used should be selected here. Choose the sensor that best describes
the sensor you are using. It is also possible to attach a 5 Volt sensor, such as a UEGO
probe, to the E6X. Since these sensors are expensive, and have limited life, it is
unlikely that they would be used in general running of the car for closed loop feedback
control, but rather as an aid during tuning.
12.1.3 The Digital Outputs
The digital output window contents change depending on the function it is to perform. A
comprehensive description of these functions can be found in CHAPTER 13 Digital Outputs
& PWM Outputs, p88.