Service & Calibration
FAQ for spark plug sensors
The spark plug sensors from AVL have two functions in parallel. The spark
plug sensor measures the combustion pressure and in addition ignites the
gas mixture in the combustion chamber. The expansion of the combustion in
the chamber is depending on many influences like the spark energy, position
of the spark etc. AVL offers a state of the art generation of spark plugs in line
with the original spark plugs. This FAQ list should help to find answers to
frequently asked questions.
Why isn’t it always possible to
determine a suitable measurement
spark plug with information like
engine type, OEM part number
or manufacturer code?
The measurement spark plugs from
AVL are only available in dedicated
heat ranges and spark protrusions.
Which values should be taken if
there is no matching AVL solution
compared to the original spark plug?
Could the electrode gap be adjusted
Does it make sense to check the
electrode gap before every usage
as well as during operation and
how could this be done?
Is it possible to use AVL spark plug
sensor as well without sealing ring?
How could you mount an already
existing spark plug in an oriented
AVL doesn’t have information about the recommended original spark plug
for every engine type and the OEM part number. The engine type itself doesn’t
define spark plug. The manufacturer helps together with conversion tables
to get most information but information like spark protrusion, customized
adaptions or heat range conversion aren’t totally clear due to missing information
or a high uncertainty. In worst case AVL would need an original spark plug to
define the correct type.
Additionally heat ranges like 4 and 6 (Bosch) and adjusted spark protrusions
are possible based on customization of standard types. Recommendation
of AVL is to choose a colder heat range if the conversion of the heat range
means a high uncertainty.
The electrode gap could be adjusted to the value of the original spark plug
for measurement spark plugs of generation ZI22, ZI33 and ZI45 due to the
electrical strength. The measurement spark plugs of the new generation are
delivered standard wise with a gap of 0.8 mm.
AVL recommends to check the electrode gap before every usage and also
during operation (every 50 to 100 h depending on fuel). The check should be
done with the tool TA32 from AVL.
The sealing surface of the AVL spark plug sensor is manufactured with a
high accuracy and less roughness in comparison to the original spark plug.
Based on this AVL measurement spark plug sensors could be used without
sealing ring if needed due to the specification.
AVL offers sealing rings (used as indexing washers) with different thicknesses
to reach the oriented position with a minimum impact to the spark potrusion.