ANTIPOLLUTION
Catalytic converter - oxygen sensor
14
CHECKS TO BE MADE BEFORE THE ANTI-
POLLUTION TEST
Ensure:
- the ignition system is operating correctly
(correct spark plugs, correctly set plug gap,
high voltage leads in good condition and
correctly connected).
- the injection system is operating correctly
(supply is correct - check using the XR25).
- the exhaust pipe is correct and is sealed.
- the EGR is operating correctly.
Check the vehicle history if possible (run out of
fuel, lack of power, use of incorrect fuel).
CHECKING ANTI-POLLUTION STANDARDS
Run the engine until the engine cooling fan has
operated twice.
Connect a correctly calibrated four gas analyser to
the exhaust tail pipe.
Keep the engine speed at 2500 rpm for
approximately 30 seconds then let the engine
return to idle speed and note the pollutant values.
CO
≤0.3 %
CO
2≥14.5 %
HC
≤100 ppm
0,97
≤λ≤1.03
1
NOTE : λ = ————
richness
λ>1→lean mixture
λ<1→rich mixture
If, after these tests, the values are correct, the
antipollution system is correct.
If the values are not correct, additional tests must
be carried out:
- Check the condition of the engine (condition
of the oil, valve clearances, timing, etc,...),
- Check the correct operation of the oxygen
sensor (see section 17) ,
- test for the presence of lead (see following
page).
If the test for the presence of lead is positive, en-
sure the vehicle uses two or three full tanks of un-
leaded fuel before replacing the oxygen sensor.
If, after all these tests have been carried out, the
values still do not conform, the catalytic converter
must be replaced. Petrol engine
14-21
