Impulse L4-1994cc 2.0L (1985)
Thermal Vacuum Valve: All Technical Service Bulletins
Engine - Stumble During Cold Operation
BULLETIN NUMBER
ISSUE DATE
GROUP
SB86-03-001
July 11, 1986
EMISSIONS
VEHICLES AFFECTED
1983-1985 Impulse (JR) non-turbocharged models before VIN F0902475 (production date 12/06/84).
SERVICE INFORMATION
Affected vehicles may exhibit engine stumble during cold operation due to early opening of the EGR valve. A re-designed EGR thermal vacuum valve
(TVV) is available to modify EGR flow. The original TVV opens at 97 degrees F (40 degrees C); the new TVV does not open until 122 degrees F (50
degrees C).
SERVICE PROCEDURE
1.
Make sure the vehicle has the old-style TVV. The old TVV (part No. 8-94213-555-0) is purple; the new TVV (part No. 8-94213-554-0) is light
blue. The part number appears on the plastic portion of the TVV. If the vehicle already has the new-style TVV, this Service Bulletin does not
apply.
2.
With the engine cold (coolant temperature below 97 degrees F), road test the vehicle and note the extent of cold stumble.
3.
Remove the vacuum hose from the EGR valve and plug the open end of the hose.
4.
Make sure coolant temperature is still below 97 degrees F. Road test the vehicle again and compare the extent of cold stumble to that noted in Step
1.
5.
If cold stumble decreases with the EGR vacuum hose disconnected, replace the purple EGR TVV with a new blue TVV bearing the part number
listed below. Unplug and reconnect the EGR vacuum hose.
PARTS INFORMATION
Part No.
Description
8-94213-554-0
EGR Thermal Vacuum
Valve (blue)
WARRANTY INFORMATION
Operation Number:
030201
Trouble Code:
71
Parts:
Dealer cost +25%
Time Allowed:
.4
