Yo,
Main suspect is the thermostat.
Following by Ford in 96 Bronco Workshop Manual, partial. Same for your 94,
except for:
92 through 95 uses the Electronic Engine Control, version Four (EEC-IV, aka On Board Diagnostics (OBD-I)) engine management computer.
96 uses the OBD-II (EEC-V) engine management computer;
4WABS (93-96);
RABS (87-92);
Air Bag (94-96);
3 ***** Automatic Locking Hubs (Built from May 95 through 96); Spark Plug Wire Routing & Firing Order (The firing order for 1987-1993 5.0Ls is 1-5-4-2-6-3-7-8. The firing order for 1994- 96 5.0Ls & all 5.8Ls is 1-3-7-2-6-5-4-8.);
R134a in 94-96;
2-piece Spindle Rolling Diaphragm Seal (RDS) used on 5/95 to 96 Broncos & F Series 1/2-ton 4WD;
Speed density EFI uses a Manifold Absolute Pressure Sensor (MAP), a Throttle Position Sensor (TPS), an Air Intake Temperature Sender (ACT) that gives the engine certain volumetric efficiencies over it's RPM range. Speed density EFI also uses what is called bank fire injection. 4 injectors are fired at one time on each side of the engine (only 2 wires for firing injectors from EEC-IV).
Mass Air Electronic Fuel Injection (EFI), aka Sequential Electronic Fuel Injection (SEFI) in 95 5.8 California models and in all 96s. Mass Air directly reads the mass of air (or number of molecules of air). By doing this, it can detect the changes in the volume of air, in addition to it's pressure & temperature. Mass air has one separate wire for each injector & fires them twice for every power stroke of the engine. This makes the injector timing more accurate & will help emissions along with power.
96 5.8 do not have the Air Injection (AIR), Secondary Air Injection; Pump (Smog Pump), Thermactor Air Bypass (TAB) & Thermactor Air Diverter (TAD) Solenoids; Diverter, Check & Bypass Valves, Cross-Over Tube, etc. But 96 5.0 does have the system.
Only 95 5.8L California models & all 96 have the Differential Pressure Feedback (DPFE) Sensor instead of EGR Valve Position (EVP) Sensor.
The 96, Vapor Management Valve (VMV) replaces the canister purge valve (CanP valve) used in EEC IV. But the 96 manual still shows CanP valve probably because it was a late addition to the 96 production line.
The Speed Control Deactivation Switch (SCDS) in a 93 Bronco is located on the driver side frame rail, but in 94 through 96 it is on the master cylinder.
Still researching other differences.
- Engine Does Not Reach Normal Operating Temperature
- Damaged water thermostat.
- Cooling fan.
PINPOINT TEST C: ENGINE DOES NOT REACH NORMAL OPERATING TEMPERATURE
C1 CHECK FOR FROZEN FAN CLUTCH
Did fan clutch pass test?
Yes
No
GO to
C2.
REPLACE fan clutch. REFER to
Cooling Fan Blade and Fan Clutch in the Removal and Installation portion of this section.
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CHECK THERMOSTAT OPERATION
Does thermostat begin to open and become fully open at temperatures in the specifications at the end of this section? See
http://www.diesel-dave.com/vehic/manual/stj/stj33040.htm
Yes
No
REINSTALL water thermostat and CHECK temperature gauge operation as outlined in
Section 13-01.
REPLACE thermostat.
Symptom Chart — Climate Control System
CLIMATE CONTROL SYSTEM
Condition
Possible Source
Action
- Insufficient, Erratic, or No Heat
- Low radiator coolant due to coolant leaks.
- CHECK radiator cap pressure. REPLACE if below minimum pressure. FILL to specified coolant level. PRESSURE TEST for engine cooling system and heating system leaks. SERVICE as required.
- REMOVE bugs, leaves, etc. from radiator and support or A/C condenser core fins. CHECK for:
Operation of engine fan clutchLoose drive beltSticking thermostatIncorrect ignition timingWater pump impeller damageRestricted cooling system
- SERVICE as required.
- REPLACE drive belt if cracked or worn and ADJUST drive belt tension.
- FEEL heater water hoses. If the heater water hoses are too hot to hold, the thermostat is OK. If the heater water hoses do not get too hot to hold, REPLACE the thermostat. If only one heater water hose gets hot while the other remains cool, a plugged heater water hose or heater core is indicated.
- CHECK condition of hoses.