P1127

P1127
Oxygen Sensing Adaptation Range 2 (Cylinder 1 - 3) Lean Limit.

P1129
Oxygen Sensing Adaptation Range 2 (Cylinder 4 - 6) Lean Limit.

Function:
The adaptive oxygen sensing corrects longer lasting deviations of the fuel/air mixture from lambda = 1 through changes of the calculated pilot control within the engine control module and with that the injection time.
Should the correction factor through adaptation exceed a predetermined value, the diagnosis will detect the adaptation limit.

Range 2 covers the engine operating state close to full load.

Diagnosis Conditions:
- Oxygen sensing active.
- Time elapsed after engine start-up 250 to 350 seconds.
- Engine temperature > 62°C.
- Intake air temperature < 90°C.
- Air mass flow > 35 kg/h.
- Load signal > 0.95 ms.

NOTE: If DTC P1127 or P1129 (oxygen sensing at lean limit) is stored in the memory, this means that the fuel/air mixture is too rich.

Diagnostic Procedure:



1. Checking fuel pressure.



1. Undo covering cap on test connection of fuel collection pipe and remove.
2. Connect pressure gauge (special tool P 378a) with connecting line (special tool 9559) and connect to test connection.



3. Actuating fuel pump

- with Porsche System Tester 2.
The fuel pump can be actuated with the Porsche System Tester 2 or by bridging the fuel-pump relay.

- via fuel-pump relay without Tester.
Disconnect fuel-pump relay from the central electrical board and bridge contacts 30 and 87 (identified as and 5 on the central electrical board) with a fused shop-made cable. The fuel pump must now operate or deliver fuel.

4. Nominal test values:
Stationary engine: 3.8 ± 0.2 bar.
Engine idling: 3.3 ± 0.2 bar.

NOTE: The seal or sealing ring in the brass closure cap is not exchangeable. It must therefore be used only once.

Tightening torque of new brass closure cap: 2.5 ± 0.5 Nm (2.0 ± 0.5 ft. lbs.).

2. Check fuel regulator, vacuum connection and fuel return line.
1. Remove vacuum hose at fuel pressure regulator.
2. Connect special tool 9103/2 to vacuum hose.
3. Start engine.

Display: 0.4 - 0.6 bar.

If the value is not attained, check the air intake system for leaks and check vacuum line to fuel pressure regulator for restrictions.

4. Check housing of fuel pressure regulator for outside damage.

Replace the fuel pressure regulator if it is damaged with the result that the spring pre-tensioning is increased.