Emissions - Vehicle Fails State Emission Test
BULLETIN NO.: 92-T-28CISSUE DATE: October, 1994
GROUP/SEQ. NO.: Engine
CORPORATION NO.: 286501R
SUBJECT:
Vehicle Fails State Inspection Maintenance (IMS) Emission Test (Follow Recommended Test Procedures)
Due to the addition of 1995 Saturns, this bulletin supercedes bulletin No. 92-T-28B, which should be discarded.
MODELS AFFECTED:
1991-1995 Saturns
CONDITION:
Vehicle fails part of state inspection maintenance (IMS) emission test.
CAUSE:
Some states perform the basic idle speed emission test without preconditioning the vehicle before the test, and without any second chance preconditioning after a test failure. Due to this situation, Saturn vehicles may falsely fail during this type of test. This condition occurs when the vehicle is started and subsequently tested at idle, without depressing the accelerator pedal to obtain at least a 1.6 percent throttle position allowing the engine to go into closed-loop operation. Also, the vehicle may not be at proper operating temperature to perform this test.
CORRECTION:
To avoid any false test failures when testing any 1991 - 1995 Saturn, perform the following steps before testing the vehicle.
PROCEDURE:
Emission Test Make sure that the vehicle is at proper operating temperature and in closed-loop operation before testing.
IMPORTANT:
Proper operating temperature can be established by increasing the engine idle speed to approximately 2500 rpm for two minutes with the vehicle in Neutral or Park.
1. Increase vehicle idle speed to approximately 2500 rpm for at least 30 seconds.
2. Bring vehicle to curb idle speed or desired rpm for testing.
3. Perform emission test.