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G E N E R A L T A I L P I P E T E S T I N G T I P S
1.
Read and follow the maintenance and calibration procedures outlined in this manual.
2.
Do not test exhaust emissions on vehicles that are smoking excessively or are in obvious need of engine
repair. Testing exhaust gas under such conditions may contaminate the sampling system and cause
inaccurate readings.
3.
Keep the probe tip openings clean and free of debris.
4.
Do not place the probe tip in liquids or allow liquids to be drawn into the analyzer's sampling system. If
the sampling system is contaminated by any liquids, it will affect the accuracy of any future tests.
5.
Do not place the probe in an exhaust pipe until the vehicle is at normal operating temperature. This
allows the exhaust system time to burn off any residual moisture.
6.
Test engines only when they are at normal operating temperature. Testing with a cold engine does not
provide useful test results due to fuel mixture enrichment, and will contaminate the sampling filter
quickly, requiring more frequent analyzer service intervals.
7.
Never drive a vehicle over the probe, sample hose or power cord.
8.
Perform the Leak Test periodically, especially after probe changes and filter service, to ensure accurate
analysis.
9.
Prolonged use of the analyzer in conjunction with a dynamometer and a hot-running vehicle under load
could damage the exhaust probe hose and affect readings.
10.
To comply with anti-tampering laws, always follow the manufacturer's specifications when working on
emission control devices.
11.
Always comply with the governing emission control standards and regulations in your locality when
testing exhaust emission levels.
12.
Check the manufacturer's specifications and procedures before testing a vehicle.
13.
Before testing Tailpipe emission levels, maintain engine speed at about 2000 RPM for 30 seconds,
followed by a 30-second normalization period at idle speed before reading gas values.
14.
Leaks in the exhaust system will adversely affect readings and should be repaired prior to testing.
15.
On vehicles with air injection systems, these systems should be disabled before some diagnostic tests.
Denying the system this air results in undiluted gas samples and inhibits catalytic converter operation for
more accurate diagnosis.
16.
Insert the test probe fully into the tailpipe when testing exhaust emissions to prevent diluted readings.
17.
On exhaust systems with twin tailpipes that exit a common resonator or muffler, the exhaust sample can
be diluted from outside air entering the tailpipe outlets. To prevent this, block off the pipe not used for
the sample probe.
18.
On engines with fuel injection, tailpipe emission readings are only valid at idle speed. Testing at higher
engine speeds is only valid when using a dynamometer. However, fuel injected engines should still be
conditioned with the engine speed near 2000 RPM as recommended in TESTING TIP #14.
19.
On V-type engines with only one oxygen sensor, a misfiring cylinder in one location may have more
impact on the O
2
sensor than a cylinder in another location.
NOTE:
Remember to remove the blocking device when testing is complete.
