Rough running

Using a legacy scanner like INPA, ISTA+, DeepOBD, ProTool etc. You can access the engine rough running menu. It allows you to check whether engine is balanced at idle or not.
Values must be between -200 and +200. The closer to zero, the better. Depending on the version of the diagnosis tool, the Limits might be -2.00 and +2.00.

The same tools can be used to display the spark ignition latency (spark duration) per cylinder, in milliseconds.

Idle Low load/Low RPM Overrun/Deceleration High load/Low RPM
2.05 ~ 2.3 2.2 ~ 2.5 2.5 ~ 2.8 1.0 ~ +
Common causes

Eccentric shaft sensor agin (Oil contamination inside the sensor circuit board) Vanos Solenoids partially-clogged Cylinder head non-return filter valves partially-clogged External (post-MAF) vacuum leak Faulty MAF Internal vacuum leak (Worn piston rings in one/multiple cylinders) or bent/burned/coked cylinder head valve Torn CCV diaphragm or cracked vacuum hose Partially-clogged catalytic converters (excessive backpressure at idle) Partially collapsed HVA lifter Demagnetized camshaft sensors Aging upstream oxygen sensors Bad quality gasoline (Water, low or inconsistent Octane, dirt) Agin spark plugs and/or ignition coils Timing chain slack
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