4.0 Swap need help

[RickB]

I just completed the 4.0 swap into my 1987 Ford Bronco II. I followed all the steps I've read up on to complete the swap, but I obviously messed something up on the wiring. I've double check the wiring and it all seem correct, but I still have no spark, injector pulse and no fuel pump unless I hot wire power to the pump. Any ideas?
I messaged another member who was having a similar issue and seemed to have resolve the problem, but I've not receive an answer yet. Thought maybe someone else would have an idea.

 

[RonD]

Welcome to TRS

Good page to Bookmark here: https://www.therangerstation.com/tech_library/index.shtml

Select Engines & Fuel
Then look for the 4.0l Conversion articles, there are several

What year 4.0l engine and computer with wiring harness?

1990-1994 would be more compatible with your 1987 B2

These years have a separate spark module, EDIS module, its what starts spark and sends the spark pulse to computer to start injectors
EDIS module was mounted to rad support on Rangers

The fuel pump relay turns on the fuel pump power but only runs it for 2 seconds with key on, a safety thing, so fuel pump should NOT have power when engine is not running
You can cycle key off and on and fuel pump should run for 2 seconds each time
Computer will turn on fuel pump relay full time when engine RPMs are above 400
Cranking speed of engine is 200 RPMs, so engine must start before pump is on full time


Assuming 1990-1994 computer and OBD1
CEL(check engine light), do you have one hooked up?
If not then I would use a test light to see if computer is booting up and then "seeing" the signal from the EDIS module

Look here: https://www.therangerstation.com/tech_library/OBD_I.shtml

Find the OBD1 connector on engine bay wiring harness
Connect a 12v light(or volt meter) to Battery positive, and then ground it to STO port on OBD connector, as shown, DO NOT install jumper, thats to read codes

Turn on the key, you should see the light come on or 12v on meter, this means computer is booting up, no volts means computer is missing 12volts or grounds, so not powering up

If light comes on then crank engine over, light should go OFF while cranking, that means computer is "seeing" a timing pulse from EDIS module


Also, as an aside, in the diagram the Fuel Pump slot is labeled that slot is the GROUND for the fuel pump relay
With Key ON you should see 12v at that slot, its 12v passing thru the relay
Ground that slot and fuel pump relay will close and fuel pump should be ON full time, well until Key OFF then it will shut off

 

[RickB]

Thanks that is good info.
The engine is a 1997 4.0 out of a ranger. The wiring harness is out of a 1994 explorer. It didn't have the EDIS module on the harness when I got it, so I pulled one from the wrecking yard. Since it plugged into the harness and the spark control module, I assumed it would work.....maybe thats my problem?
I've read through the conversion articles and performed the wiring accordingly.

 

[RonD]

And the Computer(PCM) what year is that?

60-pin I would assume to use the 1994 wiring harness, 1997 was 104-pin

1997 engine and fuel system should be compatible with 1994 wiring, might be some sensor connectors that don't match

Crank sensor is on the front of engine by crank pulley, it reads a tone wheel behind the pulley, this is the main timing pulse that starts spark
Crank sensor wiring goes directly to EDIS module
EDIS module is connected directly to the coil pack

So Crank sensor>>>EDIS>>>coil, and thats all there is to get spark working, assuming EDIS and coil have 12volts
Its an autonomous system, doesn't need the computer to start spark

The computer gets the "spark" signal timing to time injectors from the EDIS module

Since engine is cranking I would add fuel manually to the intake and see if you can get spark working FIRST, then you can go from there to fuel system and computer
The coil pack wiring can be mixed up
3 4
2 6
1 5
front

the 5 6 4 side can get mixed up, but these are "paired cylinders"
1 and 5
2 and 6
3 and 4
So once you have 1 2 3 done then match them to 5 6 4

 

[RickB]

1994 computer and yes it is a 60 pin. I actually have one from a 94 ranger with MT and one from a 94 explorer. Doesn't seem to matter which one I plug in.....same result.
Got the plug orientation correct.
The engine will crank over, but won't fire. So applying your knowledge, I will start at the crank sensor to see if it is providing a timing signal and work my way to the coil pack.
I do know I'm getting switched battery power to the coil pack, but I think I'm lacking the timing signal.
Again, good info.......Thanks

 

[BlackBII]

Here's the 1994 diagrams in case you need them

 

[RickB]

Thanks. I'll take a look at it when I get off work.

 

[RonD]

The CEL coming ON then then going OFF when cranking would mean Timing signal is getting to the Computer, so should be at EDIS as well

The Crank sensor generates its own AC Voltage, called a VR sensor, should see about .5-1v AC, not DC, when cranking
Its the Sine wave of the AC voltage that's the timing pulse

 

[Aviator Guy]

The CEL coming ON then then going OFF when cranking would mean Timing signal is getting to the Computer, so should be at EDIS as well

The Crank sensor generates its own AC Voltage, called a VR sensor, should see about .5-1v AC, not DC, when cranking
Its the Sine wave of the AC voltage that's the timing pulse

Hey Ron good info and I can see you have good knowledge on electrical troubleshooting! Too bad you are located in USA not in canada because I need some help to troubleshoot my 95 mustang

 

[DPDISXR4Ti]

Curious Rick, did you ever get this sorted out?