what are the differences between pre and post 1993 ohv 4.0’s?

[stamina]

i have got a complete 1999 4.0 ohv with harness and all accessories for my 1990 ranger and i don’t know all of the differences between the two (pre and post 1993/94) i already know a few of them such as the aluminum intake with no egr which i’ve already got from the yard, the wiring harness which i’m still hunting for (if anyone has one and would like to sell it that would be AWESOME) and i know the camshaft synchronizer on the older ones is 2 wire/dummy and the newer ones are 3 wire and actually do something. any other things i should know about?

 

[Eddo Rogue]

Mine's the '93. CA version. Intake is aluminum, there is EGR. Pretty sure the cam synchro has 3 wires, its the waterproof type connector, and it does do something (keeps the Check Engine light off). I think the heads were different post '94

 

[stamina]

Mine's the '93. CA version. Intake is aluminum, there is EGR. Pretty sure the cam synchro has 3 wires, its the waterproof type connector, and it does do something (keeps the Check Engine light off). I think the heads were different post '94

do you know anything about the spark plugs in the different motor designs? after the later ones use sp500 and the older ones use s486 motorcraft

 

[RonD]

You have some bad info

There was never a "dummy" Cam sensor
3 wire was a Hall Effect type
2 wire is a Variable Reluctance type
The type used needs to match the computer's software
1995 and up 4.0l OHV had Cam sensors, 1993/4 Calif 4.0l OHV had Cam sensors

EGR system is based on the Computer's year and if EGR was required in the state the Ranger was originally sold in

1990-1994 4.0l OHV Ranger used 60-wire EEC-IV(OBD1) Computer, with 1 or 2 O2 sensors, also had a separate spark module, an EDIS-6 spark system

1995-2000 4.0l OHV Ranger used 104-wire EEC-V(OBD2) Computer, with 3 or 4 O2 sensors, spark module was inside the newer model computer

1999 and up V6 Ranger computers all required a PATS "OK to Start" from a separate PATS module, or the fuel injectors wouldn't work
In 1998 PATS was optional, so 1998 computer may or may not have this

The 4.0l OHV engine itself was basically the same from 1990-2000, read here: https://www.therangerstation.com/tech_library/40rebuild.shtml

The Flywheel bolt pattern was changed from 6 to 8 bolts in 1997
The piston shapes were changed and the exhaust port size so there are some piston and head combinations that shouldn't be used, but only if mixing and matching internal parts

 

[Eddo Rogue]

Mine likes the Autolite Platinum. I think the difference of those Motorcrafts is platinum or iridium. It has a waste spark system, so regular plugs would wear out real fast.

 

[konrad911]

What I researched recently due to my 4.0 build is (in addition to above mentioned):

Pistons - 3 shapes to keep CR same for 3 different head types.

No CPS (Crank Position Sensor) on the early 4.0 OHV - there is only gear to drive oil pump (aka dummy cam sensor). No SFI (Sequential Fuel Injection) on early engines.

More accessories on crank under the camshaft cover for the late crank (1997) - additional gear.

Early block is accepting reboring to 4", while later ones do not.
Early block has different engine mount points/threaded holes location.