Engine Controls - Adjustments - 4-cyl Ford Probe I

ENGINE COMPRESSION

Check compression pressure with engine at normal operating temperature, all spark plugs removed and throttle valves wide open. Ensure battery is fully charged and starter is operating properly. Install remote starter in starter circuit. With ignition switch in the OFF position and using the remote starter, crank engine at least 5 engine revolutions per cylinder to determine engine compression. Compression readings are considered within specification if the lowest reading cylinder is within 75 percent of the highest reading.

COMPRESSION SPECIFICATIONS

VALVE CLEARANCE

Note. All models use hydraulic valve lifters. No adjustments are required.

4-CYLINDER IGNITION TIMING

1. Ensure vehicle is at operating temperature, all accessories are off and transmission is in Park or Neutral. Set parking brake. Disconnect automatic parking brake release (if equipped). Vehicle front wheels must be in straight-ahead position and curb idle speed set to specification. Connect timing light to engine.
2. On Probe non-turbo, disconnect and plug vacuum hoses at distributor. On Probe turbo, ground STI test connector. STI test connector is a single Black connector located at left front strut tower.
3. On all other models, disconnect single in-line Spark Output (SPOUT) connector near distributor in harness to TFI module. Wire color of SPOUT connector is Yellow/Light Green.
4. On all models, start engine. With engine at timing RPM, check base ignition timing. See «4-CYLINDER BASE IGNITION TIMING»(/ford/probe/i-1988-1992/remont/adjustments/#engine-controls-adjustments-4-cyl) table for specifications. Turn engine off. Reconnect vacuum hoses, wires or remove ground wire. Check ignition computed timing. See «4-CYLINDER COMPUTED IGNITION TIMING»(/ford/probe/i-1988-1992/remont/adjustments/#engine-controls-adjustments-4-cyl) table for specifications.

4-CYLINDER BASE IGNITION TIMING

4-CYLINDER COMPUTED IGNITION TIMING

1.9L MA PFI

1. Set parking brake. Ensure all accessories are off and cooling fan is off. Place automatic transmission in Park or manual transmission in Neutral. Engine must be at normal operating temperature when checking idle adjustment. Remove air cleaner.
2. Ensure throttle plate is not sticking or binding in housing. Check for proper throttle linkage operation. Ensure ignition timing is set to specification. See «4-CYLINDER IGNITION TIMING»(/ford/probe/i-1988-1992/remont/adjustments/#engine-controls-adjustments-4-cyl__4-cylinder-ignition-timing) article. Disconnect idle speed control air by-pass solenoid.
3. Start engine and run at 2000 RPM for 60 seconds. Check idle RPM. If idle is not within specification, adjust throttle plate stop screw. (Scheme 1) For idle specification, see «4-CYLINDER BASIC IDLE RPM SPECIFICATIONS»(/ford/probe/i-1988-1992/remont/adjustments/#engine-controls-adjustments-4-cyl) table in this article.
4. If idle speed adjustment was necessary, repeat step No. 3.

Scheme 1

1.9L TBI & 2.5L TBI

1. Set parking brake and block wheels. Ensure all accessories are off. Place transmission in Park (auto. trans.) or Neutral (man. trans.). Engine must be at normal operating temperature when checking idle adjustment. Ensure base ignition timing is correct. See «4-CYLINDER IGNITION TIMING»(/ford/probe/i-1988-1992/remont/adjustments/#engine-controls-adjustments-4-cyl__4-cylinder-ignition-timing) in this article. Remove air cleaner.
2. Connect a jumper wire between Self-Test Input (STI) connector and signal return pin on STI connector. (Scheme 2) STI connector is located right rear of engine, near cowl. Turn ignition on with engine off.
3. Idle Speed Control (ISC) plunger will retract within 10-15 seconds. If plunger does not retract, perform appropriate EEC-IV diagnostic procedure. See appropriate SELF-DIAGNOSTICS article. Turn ignition off and remove jumper wire. Disconnect ISC motor from harness.
4. Start engine and ensure idle speed is within specification. See «4-CYLINDER BASIC IDLE RPM SPECIFICATIONS»(/ford/probe/i-1988-1992/remont/adjustments/#engine-controls-adjustments-4-cyl) table in article. If idle speed is not to specification, remove TBI assembly from vehicle. Use a small punch to remove tamper resistant plug covering throttle stop adjusting screw. Remove and replace screw. (Scheme 3)and (Scheme 4).
5. Install TBI assembly on vehicle. Start engine and let idle stabilize. Adjust idle RPM using throttle stop adjusting screw. Turn engine off and reconnect ISC motor. Turn engine on and check for proper operation of ISC motor. Install a new tamper resistant plug over throttle stop adjusting screw.

Scheme 2

Scheme 3

Scheme 4

2.2L PFI

1. Set parking brake. Ensure all accessories are off. Connect a tachometer to engine. Start and run engine until normal operating temperature is reached. Using a jumper wire, ground the Self-Test Input (STI) connector. STI test connector is a single Black connector located at left front strut tower. Place transaxle in Park or Neutral. Ensure cooling fan is not running.
2. Observe tachometer. If idle speed is not correct, remove adjusting screw blind cap and adjust idle speed to specification. See «4-CYLINDER BASIC IDLE RPM SPECIFICATIONS»(/ford/probe/i-1988-1992/remont/adjustments/#engine-controls-adjustments-4-cyl) table in this article. After adjustment is complete, replace blind cap and remove STI jumper wire. NOTE: DO NOT tamper with adjustment screw located just to the left of the idle air adjust screw. CAUTION: Doing so may result in damage to throttle body.

Scheme 5

1. Turn all accessories off and ensure electric cooling fan is off. Place transmission in Neutral. Apply parking brake and block wheels. Allow engine to idle and reach normal operating temperature. Turn ignition off.
2. Disconnect idle speed control air by-pass valve assembly connector. Start and run engine at 1500 RPM for 30 seconds and return to idle. Ensure idle speed is within specification. See «4-CYLINDER BASIC IDLE RPM SPECIFICATIONS»(/ford/probe/i-1988-1992/remont/adjustments/#engine-controls-adjustments-4-cyl) table in this article.
3. If idle speed is not to specification, adjust idle. Turn throttle plate adjusting screw until idle is within specification. (Scheme 5)
4. If idle speed adjustment was necessary, repeat steps 2) and 3). When idle speed is set to specification, turn ignition off. Reconnect idle speed control air by-pass valve assembly connector. Ensure throttle plate is not binding in bore or that linkage is preventing throttle plate from closing.

Scheme 6

1. Turn all accessories off. Place transmission in Neutral. Apply parking brake and block wheels. Allow engine to idle and reach normal operating temperature. Ensure ignition timing is set to specifications. See «4-CYLINDER IGNITION TIMING»(/ford/probe/i-1988-1992/remont/adjustments/#engine-controls-adjustments-4-cyl__4-cylinder-ignition-timing) article. After checking ignition timing, leave in-line SPOUT connector disconnected. Turn ignition off.
2. Remove PCV hose and install Orifice (T86P-9600-A) or an orifice with a.200" diameter opening. Disconnect idle speed control air by-pass valve assembly.
3. Start and run engine at 2500 RPM for 30 seconds. With transmission in Drive (auto. trans.) or Neutral (man. trans.), check idle RPM. See «4-CYLINDER BASIC IDLE RPM SPECIFICATIONS»(/ford/probe/i-1988-1992/remont/adjustments/#engine-controls-adjustments-4-cyl) table in this article. If adjustment is necessary, adjust throttle plate stop screw. (Scheme 6) Turn engine off.
4. Reconnect ignition timing in-line spout connector. Remove orifice from PCV hose and reconnect PCV hose. Reconnect idle speed control air by-pass valve assembly connector. Ensure throttle plate is not binding in bore or that linkage is preventing throttle plate from closing.

4-CYLINDER BASIC IDLE RPM SPECIFICATIONS

COLD (FAST) IDLE ADJUSTMENT

No fast idle adjustments are possible on fuel injected models.

IDLE MIXTURE ADJUSTMENT

Note. No idle mixture adjustments are possible on any models. See appropriate G - TESTS W/ CODES article for diagnosis of incorrect idle mixture.

THROTTLE POSITION SENSOR (TPS) ADJUSTMENT

Note. Two types of TPS are used on EEC-IV system. "Level C" type is adjustable and "Level D/RD" type is nonadjustable. Throttle position sensors without slotted mounting holes are not adjustable. If voltage reading on nonadjustable TPS is not .9-1.1 volts at idle, and greater than 4 volts at wide open throttle, replace throttle position sensor.

PROBE 2.2L

1. Remove air duct from throttle body. Disconnect 3-wire connector at TPS, located at bottom of throttle body assembly. Remove plastic connector shield from male side of TPS connector. Reconnect unshielded connectors to TPS. Use extreme care not to ground the White wire.
2. Turn on ignition. Ensure throttle valve is in fully closed position. Using a DVOM, check and record voltage at Red to Black wire. Move DVOM lead and check voltage at White to Black wire. Observe voltage reading. See «PROBE 2.2L TPS VOLTAGE SPECIFICATIONS»(/ford/probe/i-1988-1992/remont/adjustments/#engine-controls-adjustments-4-cyl) table. If voltage relationship of Red to White wire is not correct, loosen mounting screws and rotate TPS to achieve correct voltage range.
3. If White wire voltage cannot be adjusted to specification, TPS must be replaced and adjustment procedure repeated on new TPS. Disconnect negative battery cable and depress brake pedal for at least 2 seconds to eliminate ECA malfunction memory.

PROBE 2.2L TPS VOLTAGE SPECIFICATIONS

Note. Two types of TPS are used on EEC-IV system. "Level C" type is adjustable and "Level D/RD" type is non-adjustable.

EXCEPT PROBE 2.2L

1. To adjust "Level C" type sensors, use EEC-IV Breakout Box (Rotunda T83L-50-EEC-IV). Connect digital voltmeter and set to 20-volt scale. Connect positive voltmeter lead to pin No. 47 and negative voltmeter lead to pin No. 46.
2. Turn ignition on. Loosen TPS hold-down screws. Rotate TPS until voltmeter reading is 1.0 volt. Tighten hold-down screws. Move throttle to Wide Open Throttle (WOT) position. Voltmeter should read 1.0 volt at idle, at least 4.0 volts at WOT and then return to 1.0 volt at idle.
3. If voltage is not as specified, perform EEC-IV QUICK TEST in G - TESTS W/ CODES article.

See also:
• 4-CYLINDER BASE IGNITION TIMING
• 4-CYLINDER IGNITION TIMING