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Tips on running a 4.0 OHV with SOHC ECU/PCM?

feedthezombie

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I've been combing the net trying to find some reliable answers to this question. I have a 98 XLT, the SOHC is on its way out. I don't care about power loss moving to an OHV, i just despise the design of the SOHC and want to put it out of the picture. SO!

From what i've found is that the 4.0 ohv will bolt up to my 5R55E, i've seen a mix of information saying you can run it using the SOHC ECU, then some saying you have to swap to an OHV ECU, then more saying you have to swap the entire engine/cabin harness/pats unit etc... (that is a pain)

I haven't been through the wiring diagrams yet to get my own opinion yet, i was hoping to hear from some folks that have done this or can confirm a few things for me.

Any help that can be passed along, i'm extremely grateful for!
 


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snoranger

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I went the other way... SOHC on OHV computer.

Honestly, the best way would be to get a donor truck. Swap the engine, harness (if your donor is the same year, then only the engine harness), computer, ign switch (PATS).
 




albi1cnobi1

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I went the other way... SOHC on OHV computer.

Honestly, the best way would be to get a donor truck. Swap the engine, harness (if your donor is the same year, then only the engine harness), computer, ign switch (PATS).

I saw this post and said to myself,"Self, it's only a matter of time before we see snoranger here." lol
 




snoranger

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I saw this post and said to myself,"Self, it's only a matter of time before we see snoranger here." lol

Thats because I'm one of the few who likes to do engine swaps the wrong way.

Not only am I running my SOHC off am OHV computer, but I also:
- swapped 1.8l into my '87 Pontiac Sunbird and used the stock 2.0l computer and modified harness.
- working on a stand-alone EDIS system, for one of the V6 forklifts we have at work, using stock 4.0l parts. The only thing I need to figure out is how to create a SAW signal, so it can adjust the timing based on load, rpm, etc.
 




albi1cnobi1

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I don't even like doing them the right way! When I grow up I wanna be like you.
 




feedthezombie

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I went the other way... SOHC on OHV computer.

Honestly, the best way would be to get a donor truck. Swap the engine, harness (if your donor is the same year, then only the engine harness), computer, ign switch (PATS).


No doubt that is an ideal way to tackle something that's hybrid like this. I've done full harness swaps on subaru's and its labor intensive more than anything which is what I'm trying to avoid. I don't want to gut interiors, swap trans ecu's, bcm's ect...

Someone had said in a post I read, maybe even on here. That the engines are similar is what sensors they use, so in "theory" if the cam/crank and so on look for or put out the same signals it would just be a matter of re-pinning or changing wires to bridge the gape from ohv engine harness to sohc ecu.

That's the method I was hoping for some confirmation on, similar to maybe what you are doing with a sohc on an ohv ecu.
 




snoranger

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No doubt that is an ideal way to tackle something that's hybrid like this. I've done full harness swaps on subaru's and its labor intensive more than anything which is what I'm trying to avoid. I don't want to gut interiors, swap trans ecu's, bcm's ect...

You dont need to do a full harness swap, get a similar year truck and just swap the engine harness. With a donor engine and the right harness its only 3 or 4 connectors.
You can use your trans with any 98+ OHV computer, no need to swap.

Someone had said in a post I read, maybe even on here. That the engines are similar is what sensors they use, so in "theory" if the cam/crank and so on look for or put out the same signals it would just be a matter of re-pinning or changing wires to bridge the gape from ohv engine harness to sohc ecu.

That's the method I was hoping for some confirmation on, similar to maybe what you are doing with a sohc on an ohv ecu.

Your engine has a few things that the OHV doesnt have:
Knock sensor
variable intake runners
24lb injectors (OHV uses 19lb)

The CMP sends a different signal. Ones a magnetic pick-up, the other is a hall-effect switch.

All the accessories are different.
power steering hose
a/c hoses

Plus a LOT more little things


This project will nickel and dime you to death without a full donor. If your dead set on the OHV (I dont blame you), find a wrecked 98+ OHV Explorer and swap the motor, harness, and computer. Pull all the little odd and ends off you need.... save yourself a ton of extra work and money. My '01 sport donor cost me $500, I've sold about $8-900 in left over parts off it. ;)
 




snoranger

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I don't even like doing them the right way! When I grow up I wanna be like you.

Then at least one of us would be grown up! I'm never going to.

:chug:
 




feedthezombie

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You dont need to do a full harness swap, get a similar year truck and just swap the engine harness. With a donor engine and the right harness its only 3 or 4 connectors.
You can use your trans with any 98+ OHV computer, no need to swap.



Your engine has a few things that the OHV doesnt have:
Knock sensor
variable intake runners
24lb injectors (OHV uses 19lb)

The CMP sends a different signal. Ones a magnetic pick-up, the other is a hall-effect switch.

All the accessories are different.
power steering hose
a/c hoses

Plus a LOT more little things


This project will nickel and dime you to death without a full donor. If your dead set on the OHV (I dont blame you), find a wrecked 98+ OHV Explorer and swap the motor, harness, and computer. Pull all the little odd and ends off you need.... save yourself a ton of extra work and money. My '01 sport donor cost me $500, I've sold about $8-900 in left over parts off it. ;)


I've been looking for a whole car to score thats late model, but so far everything i've found puts me back in the same ship that i'm in because they are SOHC. (its always nice to make back your initial investment and more usually when you find a whole car to snag :D)

I found an 01 OHV engine at a local yard with low miles for $500 and that is what spurred me to try to run it off of the SOHC ECU. It has the harness and accessories minus the AC comp so those wouldn't be a problem. But i'm not sure if the vehicle is still on the lot to rob the ECU from.

I guess the general topic your throwing at me is regardless i will need an OHV ECU to go with it and have a dealer correct the pats? and 98+ OHV ecu's will work with my 5R55E and the body module etc..? are those easier to find in a ranger? Thanks again for all the help!!!
 




feedthezombie

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OK i finally got my chassis back to rolling again, now its time to address this seriously.

i'm going tomorrow to pick up a 2000 4.0 OHV from an explorer, its complete with wire harness, ECU etc..

The last thing that i was confused on is i seen some issues with returnless fuel system vs return on the OHV compared to the SOHC. Since the engine is around the same year as my car will i run into any of those problems?
 




feedthezombie

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Scooter1430

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Bringing back this thread

I know those of you that are hard core are probably going to roll your eyes at this but I need a little clarification on this thread.

I have a 97 4x4 Explorer OHV with a bad transmission and a 96 4x2 with a bad SOHC engine Given that the body on the 97 is rusty I wanted to swap the OHV into the 96 in place of the SOHC. I figure the engine harness will plug in on the drivers side and with a computer swap the engine harness should plug and play. My big question is this, am I going to have any PATS problems and will the SOHC transmission given me any grief with my newer computer? I know the back of the engine harness unclips from the O2 sensors and transmission harness so can I simply swap the end of the wiring harness and run?

Thanks is advance for any information...
 




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