Gas tester (part no. 343265)
gas tester. Study the workshop manual for the particular car to identify the correct adjustment screws,
that control the mixture strength and the idle speed. Make a note of the initial position of the adjustments
before commencing work.The car should be thoroughly warm before the tests begin. It is not enough to
leave the car to warm while parked. The car should be taken for a drive and the tests not commenced until
water temperature, exhaust system and engine are running at normal temperature. Have to hand the
correct tools for making the necessary adjustments.
If the manual recommends a CO level at a particular engine speed, then a tachometer would be an
advantage. Ensure that the car is thoroughly warm as mentioned above, that it is parked in a con-
venient position in the open air, with the handbrake applied. NB:THE INSTRUMENT SHOULD NOT
BE PLACED DIRECTLY IN THE EXHAUST STREAM. CLEAN AIR IS REQUIRED IN THE REFERENCE CELL FOR
ACCURATE READINGS.
1. Place the Gastester Professional on a convenient flat surface close to the vehicle’s exhaust pipe outlet.
Switch off the engine temporarily while making connections. Connect the RED (+) and BLACK (-) clips to the
vehicle’s 12 V battery (Do not use this Gastester with 6v or 24v batteries).
2.The probe should be fitted to the instrument but do not insert the exhaust probe into the exhaust
pipe at this stage.
3. Restart the engine and allow a minimum period of eight minutes with the instrument probe in the
air. Set the calibration control to achieve 2% on the CO range and observe the display for a further
2 minutes minimum to ensure that the reading has stabilized.
4. IMPORTANT if it has not stabilized allow a further 2 minutes before attempting to measure ex-
haust CO level.
5. During the warm up period other ranges will give accurate readings and it is therefore useful to
check and adjust engine idle RPM.
6. Switch to the CO range with the probe in air. Do not insert the exhaust probe into the exhaust
pipe at this stage.
7. Use the rotary calibration control to carefully reset to the CALIBRATE reading of 2.0% CO. The instrument
displays two decimal places on the CO range as a result of the high resolution dis play. The last decimal
place is insignificant and when setting to 2% in air the user should not be concerned if 2.00% exactly can
not be obtained. Having set the CALIBRATE condition do not move the instrument, or move to a different
location during subsequent CO tests.
8. When the probe is subsequently inserted into the exhaust pipe, the display of the instrument
may increase or fall from the CALIBRATE condition, depending on whether the exhaust has more
than, or less than, 2% CO.
9. Ensure that the engine is set to the idle RPM stated by the manufacturer. Now insert the probe
into the vehicle’s exhaust pipe to a minimum of 3/4 of its length, i.e. 8” or 20 cm. In order for the
automatic water drain to function, the probe pipe should fall continuously from the exhaust end
to the inlet end to allow water droplets to run down. Otherwise the water will collect at the lowest
point and will have to be drained manually.
10. Wait for a period of 15 seconds for the meter to respond and a further 1 minute to stabilize (the
reading may overshoot before returning to a steady value, particularly during the initial measurement).
