Snap-On Diagnostics DGA 1000, Manual, Page: 57 / 116

Vehicle Testing
3-9
Two-Speed Idle (TSI) Test
The “typical” TSI procedure function contains three different
procedures:
• Non-Cat 1 (single speed test)
• Non-Cat 2 (single speed test)
• Catalytic Test (two speed test).
The Limits function, if turned on, can be used for all three tests.
✓
Remember, any limits entered only apply to for as long as
the same vehicle is being tested. When the exit the menu,
limit values revert to the defaults.
The two-speed idle test consists of operating the engine at a
higher engine speed, 2500 RPM, and a lower engine speed, idle.
During the higher speed mode, exhaust dilution is checked by
monitoring
CO and CO
2
, and the engine is conditioned to allow an
optimum exhaust emission idle test.
Test results are used to verify whether exhaust gas concentrations
emitted from the vehicle are within limits specified by the vehicle
manufacturer or the government. If exhaust gas concentrations
exceed those specified limits, repairs or adjustments are indicated.
✓
The test procedure used in the program is referred to as a
"pre-condition two speed idle" and it consists of a number
of steps that must be followed exactly to test the vehicle
properly. Taking too long to perform the test can cause
the procedure to abort automatically.
General Setup Procedure
Secure the vehicle as follows:
1. Place the shift selector in Park or Neutral.
2. Position wheel chocks snug to the tire tread of both front
and rear of non-drive wheels.
3. Turn off all vehicle accessories.
4. Select typical TSI procedure from the Test Menu. Press
ENTER and Home (
) to get to the Test Menu.
5. Set up the vehicle using information in Setting Up the
Vehicle‚ page 3-4 .
6. Select the type of TSI test desired:
—
Non-Cat 1 (single speed test)
— Non-Cat 2 (single speed test)
— Catalytic Test (two speed test).
7. Enter the Limits to test against, if desired and only if the
Limits function is turned on.
8. Select Start Tests.
9. Allow the Auto zero and hang-up test to proceed.
10. Start the engine and allow engine speed to stabilize.
11. Insert the exhaust probe a minimum of 12” into the tailpipe.