Fault code description for cylinder cut-out system (causal chain), ME-SFI

AD07.61-P-4000-54B

Fault code description for cylinder cut-out system (causal chain), ME-SFI

Engine 113.960 up to 5/00 with code (479) cylinder cut-out system

1

Fault code

A Cylinder cut-out system ON

 Intake valve of cylinder 2, 3, 5 or 8 is still actuated

B Cylinder cut-out system OFF

 Exhaust valve of cylinder 5 is not actuated

 Exhaust valve of cylinder 2 is not actuated

 Exhaust valve of cylinder 3 is not actuated

 Exhaust valve of cylinder 8 is not actuated

2

Fault storage

Activation of malfunction indicator lamp for engine diagnosis

after the end of the test period and faults

A no activation of the malfunction indicator lamp

B after two successive driving cycles with faults

3

Frequency of the test

Monitoring period

A continuous with cylinder cut-out system ON

B briefly after switching cylinder cut-out system ON  OFF

4

Fault setting conditions

Number of detected combustion misfires or increased irregular running (detection via smooth operation assessment)

5

Test prerequisites

- engine speed approx. 500 - 4500 rpm and constant

- mean constant load (intake manifold absolute pressure approx. 200 - 1000 hPa)

- cylinder cut-out system released (no fault to)

- no fault in hot film mass air flow sensor, crankshaft position sensor, pressure sensor (intake manifold)

- no fault in cylinder cut-out system valve (output stages)

- no fault in oil pressure or oil level

- no misfires "damaging to TWC"

- diagnosis for exhaust gas recirculation not active

- safety fuel cut-off not active

- emergency running throttle valve actuator not active

6

Test sequence

A Monitoring to determine whether, after cylinder cut-out system ON, all the intake valves of cylinders 2, 3, 5 and 8 remain closed (rocker arm coupling released, coupling pin disengaged).
If not, the cylinders that are actually switched off suck the fresh air away from the other cylinders and this leads to misfires. If too many misfires are detected, the cylinder cut-out system is then switched off for a short test phase. If misfires now no longer occur, it is determined that there is a fault at one intake valve and the fault is set.

B Monitoring to determine whether, after cylinder cut-out system OFF, all the exhaust valves open (rocker arm coupling locked, coupling pin engaged). If not, too many misfires are detected at the corresponding cylinder and the fault is set.
The diagnosis also identifies if both intake valves of one cylinder do not open.

7



- If the rocker arm coupling of an intake valve sticks, obvious engine noises occur (regular, speed-dependent backfire into intake manifold due to pressure expansion, most obvious after switching cylinder cut-out system OFF  ON)

- If this fault occurs, the engine diagnosis malfunction indicator lamp is activated immediately due to the simultaneously active fault identification for a misfire "damaging to TWC".