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3.8
Compensation of temperature influence
Temperature sensors are situated on the receiving chambers.
The operating temperatures measured there are taken into consi-
deration during fine-tuning of the exhaust-gas analyzer and during
the conversion of the measured value into the displayed value.
The correction factors required for this purpose are ascertained
specifically for each measuring channel (HC, CO and CO
during an automatic temperature-compensation process (see
Sections 4.1.13 and 4.4).
3.9
Engine-speed measurement
On the rear side of the exhaust-gas analyzer, an inductive clamp-
on sensor can be connected to the designated jack and a
connecting line to terminal 1 or an optical pulse generator
connected (Figure 2, Pos. 7). In order to permit measurements to
be carried out on engines with differing numbers of cylinders and
at different signal sources, the exhaust-gas analyzer can be
informed of the number of pulses (PU) for each two crankshaft
revolutions. The pulse count is adjusted using the button for
selecting 2-stroke or 4-stroke measurement (Figure 1, Pos. 14).
Examples:
4-cylinder four-stroke engine; signal source
= cable to spark plug
Correct setting: PU = 1
4-cylinder four-stroke engine; signal source
= cable before distributor
Correct setting: PU = 4
The pulse count is adjusted for the exhaust-gas analyzer in the
range of 1 to 12 by pressing the "Select" button (Figure 2,
Pos. 25) several times.
3.10
Oil-temperature measurement (optional)
The temperature sensor required for this measurement is con-
nected to the designated jack on the rear side of the exhaust-gas
analyzer (Figure 2, Pos. 27). In analysis mode, the oil-tempera-
ture display is automatically switched over to the lambda value
(excess-air factor) if the measured CO
2 % vol., that is, when vehicle exhaust gases are flowing through
the analyzer. To obtain this option, the functions "Lambda
measurement" and "Oxygen measurement" must be acti-
vated (see Sections 4.1.2 and 4.1.3).
3.11
Lambda measurement
The exhaust-gas analyzer calculates the excess-air factor from
the measured concentrations of CO, HC, CO
lambda value is indicated on the display if the measured CO
content surpasses 2 % and both the oxygen measurement and
lambda measurement functions are activated. The oxygen mea-
surement is extremely important for calculating the excess-air
factor. An imprecise oxygen measurement leads to an incorrect
calculation of the excess-air factor. The lambda measurement
function can be deactivated (Section 4.1.2).
3.12
The exhaust-gas analyzer calculates the true CO concentration
(CO
cess, leaks in the exhaust system, for example, are taken into
consideration.
The true CO concentration is only printed out or is displayed on
)
the engine tester during operation with MOT 501. This function
2
can be deactivated (Section 4.1.4).
3.13
When the exhaust-gas analyzer has been switched to "Input
mode" (also see Section 4.1, input functions), it can be parame-
terized in accordance with the intended task. It is necessary to
break a test seal (in some countries) in order to get into input
mode.
3.14
! Only Original Bosch filters part number 1 687 432 005 may
Particles and aerosols are removed from the test gas by means
of a cascade of filters.
Particles constitute solid bodies such as dust and soot, while
aerosols are tiny droplets of fluid which condense in the gas duct
and analyzing chambers. There, they form a coating which may
lead to error messages. Therefore, use of the correct filters is
extremely important.
content exceeds
2
and O
. The
2
2
2
Corrected CO concentration (CO
) from the concentrations of CO and CO
vrai
Parameterization
Filtration
be used!
)
vrai
. For this pro-
2
7
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