Haltech E6A - Manual (Page 79)

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NOTE: CLOSED LOOP CONTROL WILL NOT WORK FOR THE FIRST 2
MINUTES THE ECU IS ON, THIS ALLOWS SUFFICIENT TIME FOR THE
OXYGEN SENSOR TO WARM UP TO OPERATING TEMPERATURE.
Lower RPM Limit: The engine must be running above this speed for the closed loop
function to operate. Normally this would be set a few hundred rpm above or below idle,
depending on whether you wish closed loop control to occur at idle speeds.
Upper Throttle Limit: It is generally undesirable to run an engine at stoichiometric air-fuel
ratio when under load. This parameter is used to determine when the driver is demanding
sufficient engine output to disengage the closed loop function. The smaller this number, the
earlier the feedback control will drop out.
Engine Cycles Between Corrections: The oxygen sensor does not respond immediately to
the exhaust gases of the combustion which has just taken place. There is a gas transportation
time from the engine to the sensor, plus the sensor reaction time itself. Consequently, the ECU
counts a number of engine cycles before accepting the reading from the oxygen 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 E6A 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, around 600mV. 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.
NB: 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 E6A. 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