What happens is, the O2 sensor says "You're RICH!" and it leans it out. However, it will shove the "normal operating condition" from ideally dead center of the enrich/lean range to the lean edge; it'll be hard to lean it out further if it needs to. (Using the 92/93 ECU with 94+ injectors).

Also, you may get CELs for the non-existent EGR not working ...

Going the other way, it'll be lean on cold start and might not enrich enough on WOT to avoid detonation (while it's also open loop); when closed loop, it'll run a higher duty cycle, but again, you're pushing the enrich side of the adjustment range.

RwP

 

Computer # in truck is 56028260

 

Would it work with the 92/93 injectors to match the PCM? By work aside from operate like it was a 93 I also am thinking better mileage with smaller injectors.

 

No; the ECU will just run a higher duty cycle for the same demand.

It's not a all-or-nothing; the injector size determines how much gas can flow at max, but it rarely if ever flows that much on a street car; not uncommon to run 5% or less due to the duty cycle.

And you'll still have the "OH CRAP EGR BUSTICATED!!" errors due to the non-existent EGR not working.

RwP

 

Thank You

 

Yes, the computer will work just fine, with a few issues. The fuel mapping will be wider on the Mopar HP PCM, so it can and will adjust to the needs of the system.
The 92-93 fuel systems use a lower PSI ful pressure regulator (31psi, 39 with no vacuum) vs the 94-95 system (35-45 psi).
The quick search I have done shows the 92-95 5.2 injectors fuel rate is the same at 18.2 lb/hr (see link below)
So if anything it will be on the rich side due to the higher psi fuel pressure regulator on the 94 fuel system, not due to the injectors, but mostly only at lower RMP's as the 93 pcm will expect higher psi at higher rpms so it will be in the range of the 94 systems output.

So you can just add in a universal fuel pressure regulator in line as the 94 regulator is in the tank. A adjustable one would be best.

As far as I am aware, the 92-95 Dakota and Ram have an EGR system, at least the Factory manual has it stated in all those years. So there will be no problem with the EGR system.
But if you did not have an EGR system all you would have to do is install the EGR solenoid and cap off the ends, I did this for over 15 years without a single check engine light due to the EGR being missing, as I installed a 5.9 from a 2000 Dakota and a 94 Ram 5.9 Mopar HP PCM.

Also, the 94-up uses an electronic speedometer system. So if you use the 92-93 PCM your speedometer will not work as well as the cruise control and probably overdrive and the TCC. You should be able to get a mechanical speedo gauge as well as the cable and the 93 speedo and wire it up directly to the correct PCM connector, then they all will work.

Now the RAM PCM will work as well. The 94-95 Ram PCM uses a transmission temp sensor which the Dakota doesn't use. But you can install one easy, just add in a Tee into the Transmission coolant line and add in the sensor, or just add in a 1k (I think, I did a write up years ago on it) resistor in line to ground for that pin on the PCM connector.

https://dodgeforum.com/forum/1st-gen...ml#post2592323
http://www.fuelinjector.citymaker.co...INJECTORS.html

 

A few corrections.

Going off FiveOhMotorSports' web site, the 92/93 get 19lb @ 43.5PSI ( https://www.fiveomotorsport.com/prod...h/?v=14558#srp ).

The 94/95 get a 24lb @ 43.5PSI injector ( https://www.fiveomotorsport.com/prod...h/?v=12655#srp ).

I didn't consider the fuel pressure difference; that can be handled easily enough with an external regulator.

But the base flow rate is still higher for 94+ injectors.

94/95 do list the EGR parts; I may have been mistaken in my notes on that.

The speedometer isn't drive off the ECU for 94-96; they're driven off the VSS signal, so all you need to do is to leave the VSS there (and that's not even part of the engine; that's external, so not a consideration when swapping motors.)

My 1988 has a mechanical speedo AND a VSS; the VSS used for cruise and to tell the ECU what speed I'm doing. It's just a feed through; the VSS bolts to the transmission and the cable bolts to the VSS.

RwP

 

Wow!!!, Thanks guys!
So If I gleaned the info from this correctly.All this comp would need is a trans temp guage?
What I need is this computer?
https://www.factorychryslerparts.com.../P5249545.html

Looks like this one is for the Ram truck and the Dakota.
Wow, again.. With a little research.. I guess I shouldv'e bought a Chevrolet.. I grew up with hotrod Fords and thought I was a redheaded stepchild.. Wanna get dropped like a prom date with a lazy eye? Get a Gen 1. Life was so much simpler before all this crap.. Sad thing is I can find TZ parts easier than this..