Tune-Up - 4-cyl Ford Thunderbird IX

VEHICLE IDENTIFICATION NUMBER CODE

Engine can be identified by eighth character of Vehicle Identification Number (VIN). The VIN number is stamped on a metal plate attached to top left corner of instrument panel cover and is visible through windshield.

VIN ENGINE CODES

Note. Throughout this article, 2.3L engines will be referred to as OHC and HSC. Overhead Cam (OHC) engines are used in rear wheel drive models. High Swirl Combustion (HSC) engines are used in front wheel drive models.

TUNE-UP NOTES

Note. When performing tune-up procedures described in this article, the following notes and precautions must be followed

Due to late changes and corrections, always refer to Engine Tune-Up Decal in engine compartment before performing tune-up. If manual and decal differ, always use decal specifications.

Do not allow or create a condition of engine misfire in more than one cylinder for an extended period of time. Damage to catalytic converter may occur due to loading converter with unburned air/fuel mixture.

Do not add fuel system cleaning agents to fuel tank or carburetor as they can damage the catalytic converter.

Before making a compression test or cranking engine using a remote starting switch, disconnect coil wire from distributor and secure to a good ground.

ENGINE COMPRESSION

Test compression with all spark plugs removed and engine warm. Crank engine through at least 5 compression strokes before recording pressure. Maximum compression variation between highest and lowest cylinder must not exceed 25%.

SPARK PLUGS

SPARK PLUG TYPE

SPARK PLUG INSTALLATION

HIGH TENSION WIRE RESISTANCE

1. Loosen wires from spark plugs by twisting spark plug boot carefully to loosen seal on spark plug. Remove wires by pulling on plug boot. Remove distributor cap from distributor, leaving wires connected to cap. NOTE: DO NOT disconnect wires from distributor cap unless replacement is necessary.
2. Using an ohmmeter, check resistance of each wire by connecting one ohmmeter lead to spark plug terminal and other lead to distributor cap insert. If more than 5000 ohms resistance per inch, remove wire and test again. If it's still over 5000 ohms per inch, replace wire.

Note. Whenever a high tension wire is disconnected, the interior of the spark plug terminal boot must be coated with silicone grease before reconnection.

IGNITION TIMING

Note. Timing instrument should be connected to number one spark plug wire using an adapter or snap-on connector. Do not puncture spark plug wire or boot to make connection.

1. Place transmission in Neutral (man. trans.) or "P" (auto. trans.). Turn air conditioner and heater off. On 1.6L 2-Bbl. engines, disconnect and plug vacuum lines at distributor. On all models, connect a timing light and tachometer to engine.
2. On all except 1.6L 2-Bbl., disconnect Black single wire connector near distributor. On 1.6L 2-Bbl. engines only, disconnect barometric pressure switch and connect a jumper wire across ignition module connector pins (Black and Yellow wires).
3. On all models, start engine and warm to normal operating temperature. With engine at timing RPM, adjust initial ignition timing. Remove jumper wire. Reconnect all connectors and vacuum hoses. Remove all test equipment.

IGNITION TIMING SPECIFICATIONS

FUEL PUMP

Make all tests with engine at normal operating temperature, engine at idle speed and transmission in Neutral. When making pressure test, pinch off pump-to-tank fuel return line.

FUEL PUMP PERFORMANCE

VALVE CLEARANCE

Note. Although the valves are not adjustable, it is extremely critical that the valves are checked for maximum clearance. Repeated valve and/or valve seat refacing will decrease the clearance to the point that the tappet will cease to function and the valve will be held open. Replace components when clearance is not within specification.

VALVE CLEARANCE ADJUSTMENT

1.6L

I-E-I-E-I-E-I-E (Front-to-rear).

2.3L OHC

E-I-E-I-E-I-E-I (Front-to-rear).

2.3L HSC

I-E-I-E-E-I-E-I (Front-to-rear).

DISTRIBUTOR

All models use Thick Film Integrated (TFI) ignition systems. 1.6L 2-Bbl. uses TFI-I. All other engines use TFI-IV. The TFI system uses a small module attached to the distributor body.

1.6L Firing Order and Timing Marks. Scheme 1

2.3L OHC Firing Order and Timing Marks. Scheme 2

2.3L HSC Firing Order and Timing Marks. Scheme 3

Models With Vacuum Operated Throttle Modulator (VOTM)

1. Place transmission in "P" (auto. trans.) or Neutral (man. trans.). Start engine and warm to normal operating temperature. Place A/C heat selector in "HEAT" position, blower on high speed, if equipped. Disconnect vacuum hose from VOTM and plug (A/C only).
2. Connect a vacuum hose from intake manifold vacuum to VOTM. Disconnect and plug vacuum hose at by-pass section of thermactor air control valve. Run engine until cooling fan comes on.
3. Place transmission in Neutral. Adjust VOTM idle speed by turning VOTM-RPM adjusting screw. (Scheme 4) If vehicle is equipped with a dashpot, check/adjust clearance on Fed. H.O. with man. trans. to.138-.177" (3.5-4.5 mm) or all other models to.078-.118" (2.0-3.0 mm). Remove test equipment and return vacuum hoses to original positions.

1.6L VOTM-RPM Adjusting Screw Location. Scheme 4

CURB IDLE SPEED (RPM) (1.6L 2-BBL. MODELS WITH VOTM)

Models Without Idle Speed Control (ISC)

1. Place transmission in "P" (auto. trans.) or Neutral (man. trans.). Start engine and warm to normal operating temperature. Disconnect and plug vacuum hose at by-pass section of thermactor air control valve.
2. Place fast idle adjusting screw on 2nd highest step of fast idle cam. Run engine until cooling fan comes on. Slightly depress throttle to allow fast idle cam to rotate. Place transmission in Neutral and check/adjust idle RPM. (Scheme 5)
3. Place transmission in "P" (auto. trans.) or Neutral (man. trans.). Momentarily increase engine RPM and recheck idle speed. If vehicle is equipped with a dashpot, check/adjust clearance to.06-.09" (1.5-2.5 mm). Remove test equipment and return vacuum hoses to original locations.

1.6L Without ISC Curb & Fast Idle Adjusting Screw Locations. Scheme 5

CURB IDLE SPEED (RPM) (1.6L 2-BBL. MODELS WITHOUT ISC)

Models With Idle Speed Control (ISC)

1. Place transmission or "P" (auto. trans.) or Neutral (man. trans.). Place A/C heater selector in "OFF" position. Start engine and warm to normal operating temperature. Disconnect and plug vacuum hose at by-pass section of thermactor air control valve.
2. Place fast idle adjusting screw on 2nd highest step of fast idle cam. Run engine until cooling fan comes on. Slightly depress throttle to allow fast idle cam to rotate. Place transmission in "D" (auto. trans.) and check idle speed.
3. If adjustment is required: Place transmission in "P" (auto. trans.). Disconnect and plug vacuum hose from ISC. Connect vacuum pump to ISC and apply enough vacuum to retract ISC plunger clear of ISC adjusting screw.
4. Place transmission in "D" (auto. trans.), if RPM is not within specification, turn throttle stop adjusting screw to obtain specified RPM. Place transmission in "P" (auto. trans.). Remove vacuum pump and plug from ISC hose and connect hose to ISC.
5. Place transmission in "D" (auto. trans.), if RPM is not within specification, adjust RPM by turning ISC adjustment screw. (Scheme 6) Place transmission in "P" (auto. trans.).
6. Momentarily increase engine RPM, place transmission in "D" (auto. trans.) and recheck idle speed. Remove test equipment and return vacuum hoses to original locations.

1.6L ISC Adjustment Screw Location. Scheme 6

CURB IDLE SPEED (RPM) (1.6L 2-BBL. MODELS W/ISC MOTOR)

HOT (SLOW) IDLE RPM (1.6L EFI)

Note. The following procedure provides a means of verifying initial engine RPM setting with ISC disconnected. If idle speed is not correct, it will be necessary to perform appropriate EEC-IV diagnostic procedure.

1. Place transmission in "P" (auto. trans.) or Neutral (man. trans.). Start engine and warm to normal operating temperature. Turn engine off. Disconnect and plug both vacuum hoses at EGR solenoid valve. Disconnect idle speed control (ISC) power lead. Start engine and operate at 2000 RPM for 60 seconds. NOTE: Make sure that cooling fan is operating when idle speed adjustment is made.
2. Place transmission in "D" (auto. trans.). Check/adjust idle speed within 2 minutes after returning engine to idle, adjust by using throttle plate adjusting screw. (Scheme 7) Remove test equipment, connect vacuum hoses and lead to original locations.

1.6L EFI Throttle Plate Adjusting Screw Location. Scheme 7

CURB IDLE SPEED SPECIFICATIONS (1.6L EFI)

HOT (SLOW) IDLE RPM (2.3L OHC 1-BBL.)

Note. Curb idle speed is not adjustable. The following procedures check curb idle speed and provide for adjustment of throttle plate speed, fast idle speed and idle speed control (ISC) motor extension. If curb idle speed is still not correct, it will be necessary to perform appropriate EEC-IV diagnostic procedure.

Closed Throttle Plate Adjustment

1. Apply parking brake, block drive wheels and warm engine to normal operating temperature. Remove air cleaner and disconnect and plug vacuum line at bottom of air cleaner. Turn off all accessories.
2. Hold throttle open to maintain 1000 RPM while at the same time pressing lightly on ISC motor shaft. After shaft retracts completely, release throttle and quickly unplug ISC motor connector. NOTE: If electric cooling fan comes on, disconnect power lead to disable fan.
3. Check closed throttle plate RPM while vehicle is in Neutral. If speed is not correct, remove tamper resistant cap with pliers. Adjust speed by turning throttle plate stop screw. Remove test equipment, connect ISC motor connector. Install air cleaner assembly.

Curb Idle Speed Check

1. Turn all accessories off. Check curb idle speed. If not correct, perform EEC-IV diagnostic routine for incorrect idle speed. If adjustment has been made according to EEC-IV procedures, the bowl vent set must be checked/adjusted as follows
2. Allow engine to run at curb idle. Disconnect ISC electrical connector. Engine should remain at curb idle speed. Turn engine off. Throttle position should not change.
3. Open throttle so vent lever does not touch bowl vent rod. Close throttle to idle set position and measure travel of fuel bowl vent rod from open throttle position. Travel should be.10-.15" (2.5-3.8 mm).
4. If not within specifications, bend throttle vent lever at notch to obtain required travel. (Scheme 9) Remove test equipment, connect ISC electrical connector and install air cleaner.

Fast Idle Speed Adjustment

1. Disconnect purge solenoid electrical connector. Disconnect and plug EGR vacuum line. Turn all accessories off.
2. Run engine on second highest step of fast idle cam for 30 seconds. Verify fast idle speed. Adjust speed with fast idle screw, if necessary.

Idle Speed Control Motor Adjustment

1. Disconnect purge solenoid electrical connector. Disconnect and plug EGR vacuum line. Turn all accessories off. Start engine and run at idle for 30 seconds.
2. Open throttle until engine is running at 2500 RPM. Hold engine at this setting and disconnect ISC motor electrical connector. Verify that ISC motor has fully extended.
3. Release throttle and immediately check ISC motor maximum extension RPM. Engine RPM must be checked, and if required, adjusted within 15 seconds. If additional time is required, connect ISC motor and repeat steps 1) through 3).
4. If necessary, adjust ISC maximum extension RPM using an Allen wrench on adjusting screw. (Scheme 8) After adjustment, tighten adjusting screw jam nut to 25 INCH lbs. (2.5 N.m). Remove test equipment, connect EGR vacuum hose and purge solenoid electrical connector.

2.3L OHC 1-Bbl. Idle Speed Adjusting Locations. Scheme 8

CURB IDLE SPEED (RPM) (2.3L OHC 1-BBL.)

2.3L OHC 1-Bbl. Bowl Vent Rod Travel Adjustment. Scheme 9

HOT (SLOW) IDLE RPM (2.3L EFI/TURBO)

Note. This adjustment procedure is only to be performed if curb idle is not within 825-975 RPM (man. trans.) or 925-1075 RPM (auto. trans.). Curb idle speed is controlled by the EEC-IV processor assembly and idle speed control air by-pass valve assembly. If idle RPM is not correct after performing this procedure, EEC-IV diagnosis is needed.

1. Place transmission in Neutral. Turn A/C heater switch to "OFF" position. Start engine and warm to normal operating temperature, then turn it off. Disconnect power lead to idle speed control air by-pass valve.
2. Start engine and operate at 2000 RPM for 2 minutes. If electric cooling fan comes on, disconnect power lead to fan. Let engine idle and check base idle speed. Adjust curb idle speed by adjusting throttle plate stop screw. (Scheme 10)
3. Turn engine off and reconnect by-pass valve power lead and electric fan power lead. Move throttle plate to ensure it is not stuck in the bore.

Note. If idle speed is too high, turn ignition switch to "OFF" and then restart vehicle.

BASE IDLE SPEED (RPM)

2.3L EFI Turbo Throttle Plate Adjusting Screw Location. Scheme 10

HOT (SLOW) IDLE RPM (2.3L HSC)

Note. If for any reason the battery is disconnected or the vehicle has to be jump started this procedure may need to be performed. Curb idle speed is not adjustable.

1. Set parking brake and block wheels. Place vehicle in Reverse when checking curb idle, if vehicle is equipped with automatic parking brake. Start engine and warm to normal operating temperature and check for vacuum leaks. Turn all accessories off.
2. Place transmission in "D" (auto. trans.), "R" on vehicles with automatic parking brake or Neutral (man. trans.). Run engine at idle for 2 minutes idle speed should be within specification.
3. Place transmission in "P" (auto. trans.). Engine idle speed should increase by approximately 100 RPM. Lightly step on and off accelerator. Engine RPM should return to specification.
4. If RPM remains high, repeat procedure as it may take the system 2 minutes to reset. If idle speed is not correct, perform appropriate EEC-IV diagnostic procedure.

CURB IDLE SPEED (RPM)

Note. If curb idle is within specification, verify that throttle linkage is free and that cruise control (if equipped) is not holding throttle open. If it is observed that the throttle lever is not in contact with ISC motor while the engine is running, but held open by throttle stop screw, this screw must be adjusted.

Scheme 11

1. Verify that there are no vacuum leaks. Turn engine off and remove air cleaner. Find self-test connector and self-test input connector in engine compartment. Connect a jumper wire between self-test input connector and signal return pin on self-test connector. (Scheme 11)
2. Turn ignition key to "ON" position. Do not start engine. ISC plunger should retract. Wait until plunger is fully retracted (10-15 seconds). If plunger does not retract, perform appropriate EEC-IV diagnostic procedure. (Scheme 11): Retracting ISC Plunger (Used On 2.3L HSC Engine Only)
3. Return key to "OFF" position, wait 10-15 seconds and remove jumper wire. Remove CFI assembly from vehicle. Using an ice pick or small punch to remove welsh plug covering throttle stop adjusting screw. Remove and replace screw. (Scheme 12)
4. With throttle plates closed, turn screw inward until there is a.005" (.13 mm) gap between screw tip and throttle lever surface which it contacts. Turn screw an additional one turn. Install new welsh plug. Install CFI assembly on vehicle, stabilize engine and check for proper operation of ISC system.

Throttle Adjustment Screw Location (Used On 2.3L HSC Engine Only). Scheme 12

IDLE MIXTURE ADJUSTMENT

Note. No idle mixture adjustment is possible on vehicles with 1.6L EFI, 2.3L EFI, or 2.3L HSC. If engine performance is unsatisfactory, EEC-IV service is required.

Mixture Screw Plug Removal - 1.6L 2-Bbl.

1. Remove carburetor from engine. Center punch a mark on mixture screw plug. Drill a 3/32" hole through both the steel and plastic plug.
2. Install a screw extractor into hole and remove steel and plastic plugs. Reinstall carburetor on vehicle. After mixture adjustment procedures have been completed, install a new plug.

Propane Enrichment Procedure 1.6L 2-Bbl. & 2.3L OHC l-Bbl.

1. Apply parking brake and block wheels. Disconnect automatic brake release, if equipped, and plug vacuum connection. Connect tachometer and timing light to engine. Ensure hot idle compensator is closed (if equipped). Disconnect fuel evaporative purge return hose at engine and plug hose fitting.
2. Disconnect fuel evaporative purge hose at air cleaner and plug fitting on air cleaner. Disconnect fresh air duct from air cleaner, and insert propane hose 3/4 way into air cleaner duct. NOTE: Leave all vacuum lines attached to air cleaner. Air cleaner may be positioned aside for adjustments, but must be in place during speed checks.
3. Revise air injection dump valves as follows: If valve has 2 vacuum fittings, disconnect and plug the hoses. If only 1 vacuum fitting, disconnect and plug the hose, then run a vacuum hose from fitting to manifold vacuum.
4. On 2.3L OHC 1-Bbl. engines with feedback carburetors, disconnect electrical lead wire from electric ported vacuum switch (PVS). On 1.6L engines with automatic transmissions, disconnect and plug vacuum hose at ISC. Connect a vacuum pump to ISC and apply enough vacuum to retract ISC plunger clear of throttle linkage.
5. On all models, check and adjust curb idle and engine timing. Remove PCV valve from valve cover and allow to draw fresh air. Run engine briefly at 2500 RPM. NOTE: Propane bottle must be in a vertical position. If engine speed will not drop, check gas supply in propane bottle.
6. With engine idling and transmission in Neutral (man. trans.) or "D" (auto. trans.), slowly open propane valve and watch for RPM gain. When RPM begins to drop off, note maximum speed gain. If gain is within "RPM Gain", do not adjust.
7. If not correct, remove carburetor and mixture screw plug. Reinstall carburetor and run engine until warm, then accelerate briefly to 2500 RPM. Proceed with adjustment.
8. If measured speed gain was too high, turn mixture screw counterclockwise (rich) slightly, then repeat propane procedure until gain matches "Reset RPM". NOTE: After turning mixture screw, allow 15 seconds for idle to stabilize before turning screw again.
9. If measured speed gain was too low, turn mixture screw clockwise (lean) slightly, then repeat propane procedure until gain matches "Reset RPM".
10. Reconnect PCV valve and other disconnected hoses. Readjust idle speed if necessary, then remove test equipment.

PROPANE ENRICHMENT SPECIFICATIONS

COLD (FAST) IDLE RPM

Note. It is not possible to adjust fast idle on 1.6L EFI, 2.3L EFI, 2.3L HSC, or 2.3L OHC engines.

1.6L 2-BBL.

1. Place transmission in "P" (auto. trans.) or Neutral (man. trans.). Start engine and warm to normal operating temperature. Disconnect and plug vacuum hose at EGR valve. Place fast idle adjusting screw on second step of fast idle cam.
2. Run engine until cooling fan comes on. Check/adjust fast idle. If adjustment is required, loosen locknut, adjust and tighten. Connect vacuum hose to EGR valve. Remove test equipment.

FAST IDLE SPECIFICATIONS

AUTOMATIC CHOKE

All models are equipped with tamper-proof choke covers that are riveted on. No adjustment is possible.

ALTERNATOR REGULATOR

Motorcraft Solid State Electronic Regulator, calibrated and preset by manufacturer. No adjustment is required or possible on this unit. Two models are used, one for vehicles with ammeter and one for vehicles with indicator lamp.

All models use Thick Film Integrated (TFI) ignition systems. The 1.6L 2-Bbl. uses TFI-I. All other engines use TFI-IV. The TFI system uses a small module attached to the distributor body.

IGNITION COIL RESISTANCE (OHMS)

PICKUP COIL RESISTANCE (OHMS)

FUEL SYSTEM

CARBURETORS

FUEL INJECTION

ELECTRICAL SYSTEM

BATTERY SPECIFICATIONS

STARTER

Motorcraft positive engagement type.

STARTER SPECIFICATIONS

ALTERNATOR

Motor craft external regulator alternator.

ALTERNATOR SPECIFICATIONS

SERVICE INTERVALS

REPLACEMENT INTERVALS

BELT ADJUSTMENT

BELT ADJUSTMENT (1)

CAPACITIES

COOLING SYSTEM CAPACITIES

ENGINE OIL & FUEL CAPACITIES

TRANSMISSION & DIFFERENTIAL CAPACITIES

SYSTEM REFRIGERANT CAPACITIES