Any info on converting 91 to 2000 PCM

[Truedesertrat]

I just became a member looking for any possible members who may have attempted to update their 91 - 94 4.0 OHV engines to a 98 - 2000 PCM. I have extensive driveability experience and know that it can be done, but hoping someone out there may have already done this to save me some research and acquisition time. What would help me is if someone has an electrical schematic of the 2000 Explorer with the OHV engine so I can see what additional sensors I have to add. I know I can change out the harness, PCM and add any additional sensors, I just am not sure if I will have to make any engine component changes as I do not have all of the technical info on a 2000 model. By upgrading I can move into the OBD-II world and make my Explorer programmable through a power programmer versus the fixed chip I am currently running. By the way I have a 91 XLT 4X4 with Rough Country 4" lift, Rancho Niro 8000 six shock (4 frt/2 rear) conversion (with my own design changes to make it stronger and better), Warn manual hubs, 33X12.50-15 Dunlop Mud Rovers, Flowmaster Exhaust, K&N air, MSD ignition, Hypertech Powr Module, and upgraded A4LD with increased servos, boost pressure, and added clutch pack. It runs strong and climbs like crazy but I can do more if I can make additional programming changes. Since I live in the Valley of the Sun (or just outside of it) I need to contend with emissions standards required here. So any one out there have any help or info for me? I would greatly appreciate it. I have 27 years with 18 of those in driveability (especially dyno and OBD-II) so if I can help anyone else just ask.

 

[410Fortune]

Hello!

There would be NUMEROUS changes to your truck to update to the later model OBD-II PCM for the OHV.
First off they use 4 02 sensors, your truck has 1.
They have EGR your truck does not

The 97+ PCM's also have PATS built in, so you would need the PATS module, key and anything else PATS related. The OBD-II PCM for an automatic also will not control your A4LD anymore.

So basically your best bet is to either program your PCM the way you want it (talk to Doug on this forum) or do a complete drivetrain conversion using the late model OHV and transmission....

 

[ExplorerDMB]

a lot of computers now adays have a safety feature that if the computer trys to talk to the other sensors and it notices that they aren't the same or something goes wrong with the VIN -- then it will shut off forever and be ruined. A lot of chevys are like this.

-Drew

 

[410Fortune]

no they dont! hahaha if some sensors are not hooked up they will throw a code, or if its hooked up to the wrong sensors, but the PCM only looks for the security module and ignition key to match before it will work, withouth those mathcing components it will not run.

 

[Truedesertrat]

Thanks for the info, I know about the increase in O2 sensors, thats just a hole with a bung to add them, and the harness with module will accomodate them, as for the EGR, again just an intake manifold upgrade. What I want to know is what in the electrical controls the trans and what components are different from the A4LD (sometimes it's just a rewire on the harness to fool the computer(done it before). I considered the Ignition key thing, but my friends 03 doesn't have a security key so I wasn't sure if the 2000 used one(again just a simple mod to include if necessary). Still looking for the wiring schematic which will tell me all I need to know in the harness and PCM control department. I may just have to change out my trans, which isn't to hard. I can't change the engine as I would have to go through a world of paperwork with Arizona Department of Environmental Quality due to emissions testing requirements. Still want to consider all aspects before moving on. Thanks again for any info.

 

[410Fortune]

pssst:
donor vehicle.
Drivetrain swap.
Get everything you need.

A little birdie also told me you can run a SOHC in there with the OHV computer and wiring/sensors.