911 Carrera Targa F6-3600cc 3.6L SOHC (1996)
Oxygen Sensor: Description and Operation
Oxygen Sensor System Adaptation
Diagnosis of the Oxygen Sensor (O2S) System adaptation
The adaptive O2S system corrects longer lasting deviations of the fuel/air mixture of Lambda = 1 by changing the anticipatory control calculated in
the ECM and with that the changed injection timing.
The participatory control is changed multiplicatively and additively via the fuel/air mixture adaptation in such a way, that the corrections of the oxygen
sensors (FR) can be kept small so that even during unregulated operation, the fuel/air mixture is close to Lambda 1.
The procedure is based on the following assumptions:
Over the life span of the engine and through different tolerances, two basic faults may occur: the multiplicative fault and the additive fault per time
unit (false air). During idle the false air fault dominates (low air ratio, low rpm), at high air ratio the multiplicable fault dominates.
A fault combination of multiplicable and additive nature is compensated correctly when a corrective value in its dominant area is adapted.
Therefore there are two adaptation areas: the adaptation in the idle segment and the adaptation under load.
Area 1: Sector near idle = TRA
Area 2: Load sector = FRA
System description:
After dialing the adaptation values for the 02S System, the following displays may appear:
Area 1:
TRA: xxx
TRA2: xxx
Button 1 or N
Explanation:
TRA: = Adaptation in idle sector for cylinders 1 - 3
TRA2: = Adaptation in idle sector for cylinders 4 - 6
Area 2:
xxx
FRA2: xxx
Button 1 or N
Explanation:
FRA: = Adaptation under load for cylinders 1 - 3
FRA2: = Adaptation under load for cylinders 4 - 6
Oxygen sensor:
FR:
FR2:
Button 1 or N
Explanation:
FR: = Oxygen sensor (integrator) cylinders 1 - 3
FR2: = Oxygen sensor (integrator) cylinders 4 - 6
Function: After the ECM was disconnected from constant plus, the numerical values are at 1.00 (FRA) or 0 (TRA). After starting the engine first the
programmed channel is displayed.
Example:
Area 1:
TRA: 0
TRA2: 0
Button 1 or N
After release of the 02S system (depending on engine temperature) the oxygen sensor (FR) moves at about its mean value(for example 0.98 - 1.03).