Hi All,
Newby here, name is Bud

I have recently completed a motor swap on a 94 4x4 Ranger and something is not correct. The original motor was a 4.0 and the donor vehicle was a 93 4x4 with a 4.0 so I figured this was a no brainer...... Oppsy.........
The trannys are the same (both AL4D) and all accessories A/C Alt etc were kept with the original motor and just dropped in the whole ball of wax....
The first test drive I noticed some really poor performance in the mid power range and somewhat poor everywhere. Checked the Engine controll computers and noticed they were different versions. Swapped the computers and thats where I'm at now. Performance made a marked and very noticeable improvement but still not at 100% especially in the 1/2 to 3/4 power band At times it will take off and run perfect. Soon it will revert to less than perfect for no apparent reason.....It also feels as though there is a pronounced miss in the motor most of the time, if I mash the pedal it usually helps but then starts missing again when I back off it. I have not been able to get any real pattern to it all except it always starts to miss again once I back off the trottle all the way. My last test drive I also noted the temp gauge started varying quite a bit, up all the way, then back to the middle and so on? I checked my coolant and it is full, no aparent leaks...... Any help out there?

 

Anyone know if there are any sensors that may NEED to be swapped for the year change?

 

Have you checked ignition timing?

 

Yep...
More detail, motor was running great in donor truck just before swap.
and original motor was suspected of having blown head gasket or cracked head
severe overheat and coolant loss problems at end. As I owned both and the donor was a wrecked truck it seemed like the best answer.....
I think I'm gonna have to start all over with the basics and work from there,
Plugs are new
going to clean MAF sensor,
Cjange fuel filter etc.etc.etc.
I was just hoping that there was a snesor or something I needed to swap that I didn't know about.... Thanks
and shoot any more ideas at me appreciate them all......

 

MAF Sensor cleaning made a world of differance........

I am still not at 100% but what miss is left seems to be almost constant so I am thinking it is possibly a plug wire I am going to check them after dark tonight and see if I can see any arching.......
Appreciate the info from this site.......
Thanks..