Mustang V6-232 3.8L VIN 3 TBI (1984)
Idle Speed: Adjustments
Curb Idle Speed Check
1.
Set parking brake and block wheels. If equipped with automatic parking brake, always place in Reverse when checking curb idle. Make all
adjustments with engine at normal operating temperature and accessories off.
2.
After engaging transmission in Drive (or Reverse) and idling for 60 seconds, idle rpm should be within specification.
NOTE: Curb and fast idle speeds are controlled by the EEC IV processor and the idle speed control device. If the control system is operating properly,
the speeds are fixed and cannot be changed by traditional adjustment techniques.
Adjustments are sometimes required to establish the correct operating limits within which the ISC system can properly function. These adjustments, as
outlined below, will normally have no direct effect on actual idle speed and generally will not be required unless:
a. Curb idle speed is out of specification as shown on the decal.
b. The ISC motor requires replacement.
Misadjustment of the operating limits could restrict the operating range of the ISC system, so adjustments of these limits should never be made unless a
specific causal factor exists. If these operating limit adjustments do not correct an out of specification curb idle speed condition, it will be necessary to
perform the appropriate 3.8L EEC IV diagnostics.
Minimum ISC Limit Adjustment
If the curb idle is above specification, verify that the throttle linkage is free, that travel is unobstructed and that cruise control (if equipped) is not holding
the throttle open. If it is observed that the throttle lever is not in contact with the ISC motor, but held open by the throttle stop adjusting screw (TSAS),
this screw must be adjusted. This is the only reason for adjusting the TSAS as it is strictly a throttle stop and in no way affects idle speeds unless it is
holding the throttle open through misadjustment. To adjust the TSAS, the ISC motor must be fully retracted. Therefore, the following TSAS adjustment
procedure must be done in the exact sequence shown below:
1.
Shut the engine off and remove the air cleaner. In the engine compartment, find the self-test connector and self-test input (STI) connector. These
two connectors are located next to each other on the driver's side, behind the strut tower and on the EEC harness.
2.
Connect a jumper wire between the self-test input (STI) connector and the signal return pin on the self-test connector.
3.
Turn the ignition key to the run position. Do Not Start Engine.
4.
The ISC plunger will retract. Wait until plunger is fully retracted (about ten seconds). NOTE: If plunger does not retract, refer to EEC IV
diagnostics.
5.
Shut off key.
6.
Remove the jumper wire.
7.
Perform throttle stop adjustments as follows:
*Using pliers, grasp the TSAS screw threads and turn screw until it is removed from the CFI assembly. Install a new screw.
*With the throttle plates closed, turn the new screw inward until there is a .005 inch gap between the screw tip and the throttle lever surface which
it contacts.
*Turn the screw inward an additional 1-1/2 turns.
Maximum ISC Limit Adjustment
If curb idle RPM is below limit or there is reason to suspect that cold engine idle speeds are low (i.e. engine stalls), the idle speed control device may be
restricting operation. Check and adjust in the exact sequence as shown below:
1.
Shut engine off and remove air cleaner. In the engine compartment, find the self-test connector and self-test input (STI) connector. These two
connectors are located next to each other on the driver's side, behind the strut tower and on the EEC harness.
2.
Connect a jumper wire between the STI Connector and the signal return pin on the self-test connector.
3.
Turn the ignition key to the run position. Do Not Start Engine.
4.
The ISC plunger will retract. Wait until plunger is fully retracted (about ten seconds). NOTE: If plunger does not retract, refer to EEC IV
