4.0 OHV to 4.0OHC swap

[Biscus7-_]

What is different when going from a 95 4.0 to a OHC motor? any big issues And I will have the donor truck. anything would be helpful thanks

 

[adsm08]

The wiring. All the wiring.

Also the fuel system, large portions of the fuel system are different.

Beyond that, use your engine brackets for setting it on the mounts and you should be good physically.

The fuel and timing curves are different, so the SOHC computer needs to be used. If the donor truck is auto you need to keep it's transmission with it, because of computer stuff, or get a manual transmission computer.

There is also the security system, might as well just take the whole dash from the donor.

 

[Biscus7-_]

Thank you and both are auto trans

 

[fastpakr]

Wasn't there a discussion recently of running a SOHC successfully using the OBD-I management?

 

[don4331]

The SOHC will run on the OHV setup, its just kind of a dog when doing so (torque peak is 600 rpm lower, hp 1,000 on OHV). And transmission doesn't shift as smooth.

As @adsm08 says the ideal is to take the engine/transmission wiring and fuel pump/lines from the newer truck and graft it into the older one.

 

[adsm08]

Wasn't there a discussion recently of running a SOHC successfully using the OBD-I management?

Yes. But I have always questioned the validity of the claim.

SnoRanger put a SOHC in his 95 Explorer, and called it an OBDI swap, IIRC. But the 95 Explorers were OBDII. My own adventure with with trying to make a SOHC run off a 94 computer had the engine running. It also had no power and shot flames out the tail pipe. I timed the engine myself, so I'm pretty sure the cams were set correctly. I was using the factory EDIS-6 box, and may have been able to correct the issue by dropping the money on an MSD adjustable unit, but I didn't have $300 to throw at that at the time.

Even with all that, the OHV and SOHC engines use very different cam sensors. Sno had to have a piece custom made to run the cam sensor to give the OHV computer a signal it could understand. In my off the board conversations with him about it he said he never did get it installed, and so he doesn't know for sure if it would have worked right or not.

 

[Snoranger]

Yes. But I have always questioned the validity of the claim.

SnoRanger put a SOHC in his 95 Explorer, and called it an OBDI swap, IIRC. But the 95 Explorers were OBDII. My own adventure with with trying to make a SOHC run off a 94 computer had the engine running. It also had no power and shot flames out the tail pipe. I timed the engine myself, so I'm pretty sure the cams were set correctly. I was using the factory EDIS-6 box, and may have been able to correct the issue by dropping the money on an MSD adjustable unit, but I didn't have $300 to throw at that at the time.

Even with all that, the OHV and SOHC engines use very different cam sensors. Sno had to have a piece custom made to run the cam sensor to give the OHV computer a signal it could understand. In my off the board conversations with him about it he said he never did get it installed, and so he doesn't know for sure if it would have worked right or not.

My 95 Explorer had a 60 pin ECM connector... that sounds like EEC-IV to me.

I had the custom cam sync installed in my spare engine for testing... it was never 100% proven, but it was designed to match the factory OHV setup.

Get it right... I didn’t have the custom cam sync made, I made it myself.

 

[adsm08]

My 95 Explorer had a 60 pin ECM connector... that sounds like EEC-IV to me.

95 is such a messy year.

If you look at just the wiring diagrams and PE/ED it looks like it is a total either/or deal.

If you go look at the diagnostic instructions for the 4R/5R transmissions, in the DTC recording section, there, and as far as I can find ONLY there, does it call out that Rangers were OBDII, and Explorers OBDI.

Add to that the fact that I had a buddy in college with a 95 2.3L Ranger that had BOTH plugs, and the PCM would respond with DTCs on both plugs.

I could hook up with an EEC-IV tester in the engine bay, get 3 digit codes, or hook up under the dash with an OBDII reader and get P codes.

 

[JOLENE_THE_RANGER]

some info on the swap.
i did it and have it running on a obd1 computer. i can post a video of it later if anyone wants.
the sohc does not need the cam sync to run
on the stock ohv (obd1) computer/tune the sohc made 160 wheel hp and 170 tq through a c4 and 35 inch tires (the ohv did 100 hp and 140 tq in the same truck a week before i did the swap) it was a little rich on the top end of the rpm range but never leaned out nor was it ever unsafe to run throughout the rpms. after a tune it makes 180hp/ 190 tq
the couple weeks i drove it WITHOUT a tune it was a night and day difference. so much faster. was not a dog what so ever

youll want the fuel rails from a 97 sohc explorer as those are the only sohc engines that used a return style fuel system. after grabbing those your entire old fuel system will work.
everything from your ohv engine transfers over to the sohc except for the steering pump. youll need a custome high pressure steering line for that also. you can use either injectors. the ignition module is the same part number. crank sensor transfers right over and bolts on the same way. the only thing youll need to mount is the Intake air temp sensor. the obd1 has its own unit and on the sohc trucks it was combined with the MAF.
you use the old maf, old iac valve mounts the same way also . old alternator blah blah blah. i have a full write up on a different site if youre interested.

same rules apply to your 95 being obd2. except maybe the iat sensor. im not familiar with the 95 MAF.
Its seriously a super easy swap. started on saturday morning and took it for a spin monday night.