4.0 sohc Need help asap

rekles · Mar 4, 2017

Hi need some help on a 4.0 sohc ecm.
Will a 4x4 ecm work with a 2wd transmission and not throw any codes??

I am about to do a 4.0 sohc swap and the doner truck is 4x4, the recipant truck is a 2wd and i will be using the 2wd trans.

Im going from ohv to sohc

alwaysFlOoReD · Mar 4, 2017

In the years I'm familiar with there would be no problem using the 4x4 in a 2wd system. However I'm not familiar with sohc....

RonD · Mar 4, 2017

Not sure all info is included???

4x4 or 2WD is not part of Computer(EEC/EMC/PCM) programming so won't matter, over the years Rangers used 4WD control module, GEM, and the 4x4 module for 4WD shift motor control

Computer is used to control automatic transmission shifting, so transmission MODEL is important.
4.0l OHV or SOHC used A4LD, 4R55E or 5R55E trans models, that must stay the same for computer to "work" with trans.

Manual trans computers don't have "shift software" so they don't care, but also can't shift automatic.

4.0l OHV and 4.0l SOHC are different engines, OHV has 9.0:1 compression ratio, SOHC has 9.7:1 compression ratio
SOHC has to have a Knock sensor or it will ping on regular gasoline, so its computer has to have software to see "pinging" and change spark timing to avoid engine damage.
You could have 4.0l OHV computer programmed for use with SOHC with "regular gas" and "Premium" switch

If I am reading this right, you will be swapping 4.0l SOHC engine WITH ITS COMPUTER to a 2000 or earlier Ranger which is fine, not a good swap but doable.
1997 and earlier Rangers used 35psi fuel system
1998 and up(includes SOHC) used 65psi system, so have to change fuel system if 1997 or older Ranger is used

Reason you don't see this swap done much is because it is pretty much the same work as V8 swap but you get less power and a Ranger you can go out and buy stock, 2001 and up 4.0l SOHC Ranger, so no real "value added".
4.0l SOHC only has 207 horse power when running premium(93 octane) fuel, with Regular gas your at about 180-185HP, because of the pinging, so better than 4.0l OHV but not "same as V8"

rekles · Mar 5, 2017

Yes I belive both transmissions are the same witch is 5r55e I think. I was thinking about a v8 swap but I got this parts truck for $500 and it drives real nice, although I still might freshen up the motor and transfer hike it is out. I also have also 97 4.0 4x4 and with the ohv it's a a dog, that's with 35" tires and 3.55 gears though.

So just to be crystal clear every thing should just bolt up to the 2wd trans and work as it should? Also isorry here gonna be any problems with there not being a front different? Any sensors that would make the cel come on?

rekles · Mar 5, 2017

The donor truck is a 2001 4x4 , and the recipient is a 99 xlt 2wd if that helps

adsm08 · Mar 5, 2017

It will work fine as far as driveability is concerned. The big difference in the 2wd vs 4x4 computers is a bit of programming concerning the 4-low shift. There are some signals the 4x4 module would need to see that are things generally routed to the PCM, and it would relay those items to the 4WDCM if you had 4x4. Worst thing you might have using a 4x4 PCM on a 2wd truck is a network code saying it can't communicate with the 4WDCM.

RonD · Mar 5, 2017

One heads up, and not sure how it will play out.

2001 ranger/computer got its speed signal directly from the OSS sensor on transmission/transfer case, it then corrected speed for rear axle ratio and tires size(programmed in at factory), and sent out the corrected speed signal to speedometer and cruise
Computer uses that speed signal to set shift points for the 5R55E transmission

In '99 Rangers used the rear axle ABS speed sensor(VSS), its signal was sent to the ABS AND the GEM, the GEM would correct speed for tire size(factory programmed) and then send out the corrected speed to speedometer, Computer and cruise.

VSS or OSS used same type of signal, so that is not an issue.
But not sure how it will work out sending the GEM speed signal out to 2001 computer, as it will "recorrect" it as it is suppose to do, and end up with wrong speed so wrong shift points.

Transmission speed sensors are set to do 8,000PPM (pulse per mile) average, Standard Ford speedometer PPM
Rear axle speed sensors are closer to 15-20,000PPM.

The GEM changes signal back to 8,000PPM for speedometer and computer use and that could feed '01 computer, just not sure if computer will us it "as is" or "correct it"

There are 3rd party devices to fine tune PPM signals available, so not a big issue, just a heads up, and '01 computer could be reprogrammed to use speed signal "as is"

rekles · Mar 5, 2017

So your saying I'm better off finding a 2001+ transmission. Yeah I was hoping it would be just plug and play. I might just throw the 4x4 trans in and run it with the 4x4 disconnected. What about swapping a new tail end on the tyranny and disconnecting the transfer case is that a possible solution?

RonD · Mar 5, 2017

Converting 4WD to 2WD, or visa versa, requires full tear down/rebuilt on an automatic trans, so not really worth it unless transmission has failed in some other way.

An adjustable PPM converter runs about $90, Google: SGI-5E
But you won't know if you even need this until everything is up and running.

Computer could use input PPM from GEM and shift at correct RPM/Speed, it is adaptable, it "learns and remembers".

Computers and cruise controls don't have a clue of what "speed" is, all they see is a PPM signal, and in the case of cruise control if you SET it at 60mph cruise doesn't know what 60mph is, all it knows is that you SET 7,500PPM(for example), so it tries to hold that 7,500PPM by increasing or decreasing throttle position.

So when you are assembling the wiring I would mark GEM PPM out, I think it is pin1, and also Computer PPM(OSS high) IN, and OSS low(ground) IN, so you can come back and add a converter if needed.
Converter could also be used if you change tire size in the future, GEM would normally have to be reprogrammed, but you could add speedometer wire to converter output, move it from the GEM and it would show corrected speed

4.0 sohc Need help asap

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