1991 5.0 EFI Stuff

[signoff1]

have a box of stuff of used stuff mostly that i'm using to assemble this motor.
1968 bronco

Question 1 - Should i bother with the EGR spacer and tube up the coolant ports? Whats the downside of not using it?

Question 2 - If it makes sense to use it, i'd likely delete the EGR. Any issues with doing that other than the smog compliance issues.

Question 3 - i have a manual transmission(np435) to pair up, and have the 5-speed computer. I was told recently that there is an engine hardness for a manual, and another for automatic transmissions. Anyone have an idea how to identify the harness for manual?

 

[jamesroney]

1. You only need EGR cooling if you have hot gasses flowing thru the spacer. So if you have no exhaust recirculating...you have no need for EGR cooling. But one thing that the EGR cooling does provide is coolant flow in the heater circuit when the heater valve is closed. This coolant flow ensures that the Coolant Temperature Sensor is immersed in coolant that is engine temperature. If you have no flow, and you use the stock location for the CTS...It will read incorrectly and report the wrong engine temp to the computer.

2. EGR defeat is fine. But if you delete the spacer, you will have to figure out a way to hold your throttle cable...since the cable bolts to the EGR spacer. No spacer, no bolt holes.

3. It doesn't matter what transmission that your actually have in the car. All that matters is that the harness for the computer needs to match the computer. An Auto harness needs to plug into an Auto Computer. A manual harness needs to plug into a manual computer. (I don't know of anyone running a Neutral Drive Switch on a NP435...)

The RJM / Ron Francis wiring harness is select-able for either.

If you are using a FoMoCo harness, and you don't know what you have...you can use a schematic and ohm meter to check the pins at the 60 pin header to the HEGO circuit.

Have fun!

 

[Jedeka]

Look up JSmall on this site for a throttle cable bracket. I just tore down my 5.0, removed the 90* elbow and reinstalled the TB with the throttle shaft pointing down. The JSmall bracket is going to work great !

 

[garberz]

Look up JSmall on this site for a throttle cable bracket. I just tore down my 5.0, removed the 90* elbow and reinstalled the TB with the throttle shaft pointing down. The JSmall bracket is going to work great !

JSmall’s throttle cable bracket is for Ford Explorer, not the earlier Mustang EFI.

Mark.

 

[signoff1]

James - appreciate the response. We met briefly at WH swap recently, and i had a couple of green questions like these. Honestly, I'm in the "EFI I don't really know zone".
So when i say i have the harness, i actually have 2 stock harnesses, 1 that i believe came with the computer, and another that was loose, unfortunately in the same box. My problem... i either buy a new Ron Francis harness for example, or i figure out which of these 2 stock harnesses is the correct one, which i dont know how to do easily. Really dont understand the differences between them. I'm not opposed to spending some $ to make some progress, but if its a simple harness ID, and using the stock version is Ok, why not.
The gentlemen with the nice bronco we were in front of, recommended to not use the stock harness, even if i could ID it.

 

[signoff1]

about the Ron Francis RJM Harness....doesnt look like a match. Is it the TDZ-75 EFI harness? That looks like a match. But again, what is it about the stock harness that makes it not a fit? Thanks in advance

 

[signoff1]

#5
signoff1
Newbie

James - appreciate the response. We met briefly at WH swap recently, and i had a couple of green questions like these. Honestly, I'm in the "EFI I don't really know zone".
So when i say i have the harness, i actually have 2 stock harnesses, 1 that i believe came with the computer, and another that was loose, unfortunately in the same box. My problem... i either buy a new Ron Francis harness for example, or i figure out which of these 2 stock harnesses is the correct one, which i dont know how to do easily. Really dont understand the differences between them. I'm not opposed to spending some $ to make some progress, but if its a simple harness ID, and using the stock version is Ok, why not.
The gentlemen with the nice bronco we were in front of, recommended to not use the stock harness, even if i could ID it.

 

[ransil]

Harness is not plug and play so you will need to tear it down,inspect it rout wires where needed , add or extend grounds & power and configure the Auto /manual issue to fit your needs.

 

[ransil]

some reading material for you:

https://classicbroncos.com/forums/showthread.php?t=172541

and grounding it works if you don't want to get fancy.

 

[jamesroney]

#5
signoff1
Newbie

James - appreciate the response. We met briefly at WH swap recently, and i had a couple of green questions like these. Honestly, I'm in the "EFI I don't really know zone".
So when i say i have the harness, i actually have 2 stock harnesses, 1 that i believe came with the computer, and another that was loose, unfortunately in the same box. My problem... i either buy a new Ron Francis harness for example, or i figure out which of these 2 stock harnesses is the correct one, which i dont know how to do easily. Really dont understand the differences between them. I'm not opposed to spending some $ to make some progress, but if its a simple harness ID, and using the stock version is Ok, why not.
The gentlemen with the nice bronco we were in front of, recommended to not use the stock harness, even if i could ID it.

Hi, It was nice to meet you at the Wild H swap meet last week.
As far as the stock harness is concerned...there are a number of circuits that you need to identify, and provide the correct source inputs and ouputs. The beauty of the RJM harness is that they have done all that for you.

Plenty of people have run a factory harness, and have made them work. It's a giant bowl of spaghetti...and as long as you are patient, then you can figure it out. The RJM harness has reduced it to 4 wires. So they sell a lot of harnesses. I don't like the late model Factory harness, because they include a lot of Chassis wiring that you don't need. Also, the Fuel Pump Relay and ECM relay are located in various places. RJM solves all that.

There was a really good pamphlet that was published by Ford Motorsport on how to convert a factory harness. I hope that you can find it on the web. If you are good at wiring, and have lots of free time...then you can convert the factory harness. I have done several. But for $450, I just run the RJM.

 

[signoff1]

I'm in for easy...so the $ isnt the problem, i just cannot locate a RJM harness tsource to buy it from. Unless its the Ron Francis model, but it appears to be a TDZ

WH has theres for $549 right now, TBP has theres for $625, but cant come up with a RJM source.