LTD Crown Victoria V8-302 5.0L VIN F FI (1986)
Idle Speed: Adjustments
NOTE: Curb idle speed (RPM) is controlled by the EEC-IV processor and the idle speed control device. if the control system Is operating
properly, these speeds are self-compensating and cannot be changed by traditional adjustment techniques.
Adjustments are sometimes required to establish the correct operating limits within which the Idle Speed Control (ISC) system can properly function.
Misadjustment of the operating limits could restrict the operating range of the ISC system, so adjustments to the system should never be made unless a
specific causal factor has been identified.
Before any idle speed adjustments are attempted the following procedure should be performed:
1. Set parking brake and block wheels. Bring the engine to normal operating temperature and turn Off. Place the transmission in Neutral/Park. Turn
the A/C-Heat selector to the Off position.
2. Verify that the throttle linkage is free, that travel is unobstructed and that the cruise control cable (if so equipped) is not holding the throttle open.
3. Check for vacuum leaks.
4. Place transmission in Neutral and operate engine at 1800 rpm for at least 30 seconds.
5. Place transmission in Drive (A/T) or leave in Neutral for (M/T). Allow engine to stabilize.
6. Check idle speed if curb idle speed is equal to decal specification do not adjust.
7. If speeds exceed decal specification turn engine Off and disconnect the positive (+) terminal of the battery for five minutes and then re-connect.
Repeat Steps 4, 5 and 6.
8. If speeds exceed specification, perform EEC IV Quick Test, See: Powertrain Management/Computers and Control Systems/Testing and Inspection
and resolve any vehicle defects that are indicated by service output code; then repeat Steps 4, 5 and 6.
Fig. 3 Curb idle speed adjust. V8-302 Engine W/EFI
9. If speeds still exceed decal specification back out throttle plate screw until the idle speed reaches 575 +/- 20 rpm (base 5.OL A/T) 625 +/- 20 rpm
(5.OL H.O. A/T), 700 +/- 20 rpm (5.OL H.O. M/T) then back out the throttle plate stop screw one-half additional turn to bring the throttle plate
linkage into the nominal operating range of the ISC system.
