I have searched this forum and found a few threads that related, but i would like to go a little deeper and maybe verify some info. I am looking into dropping an EFI 5.9 out of a '99 in my '78 Power Wagon. I could carb it, but I would like the reliablity, driveablity, mileage...ect of fuel injection. From what I have read, the fuel injection off of anything post '95 is a returnless fuel supply, correct? Also, I have read on building a stand alone engine harness from other threads, but if anyone has experience, I would be thankful. Diagrams, pictures? Also, I have read about thinning down the harness from the bulkhead forward (engine side,) but if I am not using the harness from the firewall - back (dash and chassis), how would I plug in the computer? Isnt the computer in the under-dash harness? This isnt my first EFI conversion, just not familiar with chrysler's setup. Thanks a million, Scooter.

 

If you want to run a 99 EFI engine you will need the wiring harness and the computer from that 99 unless you are very good with wiring and have a lot of time. A computer can be moved just about anywhere if you are going to do a full homemade harness.

 

i think using the computer system out of anything 97 or newer would be a nightmare because everything is pretty much digital.

as far as gas mileage goes i don't think installing a fuel injected engine will get you better gas mileage without swapping transmissions. if i was to put the same transmission in my 81 that my 93 had they would most likely be getting the exact same gas mileage even tho 1 would be carbed and the other fuel injected.

 

Engine, harness, computer are all from same truck, so the computer will already be set up for that engine. As for the transmission upgrade, I forgot to mention that I have already done that. I am running a fresh rebuilt NV3500 5 speed. I know its lighter duty than the NV4500, but it was available at the time and was originally behind the 5.2 magnum that I already put in my truck. (Carb'd that one.)

 

ok. then i don't think you will gain much from sticking a 5.9 in there other than the more power and torque. i guess you could find the wiring out of a 95 or older truck to get it running. using the wiring out of a 99 would almost be impossible unless you swap everything including the dash.

 

Would the earlier wiring harness plug into the later fuel intake? Injectors and sensors?

 

crazzywolfie - "i don't think you will gain much from sticking a 5.9 in there other than the more power and torque."
Right....? Isnt that the point of most engine swaps?

 

i think you could swap some of the sensors from your current engine over onto the new engine but then there are thing like there only being 1 hole in the intake for 1 temp sensor. i think they also changed the plug on the injectors in 98 or so.

 

Honestly I am not all that concerned with being able to get it to run with the '99 harness and ECU. However, if someone has done it and has some advice, I wouldnt object. I am a little worried about emissions. O2s in particular. I dont have testing here, or inspections, but I dont want my engine to run too rich or lean because both of my O2s have the same reading. I am not installing a cat so the pre-cat and post-cat O2s will read the same. Will it matter or do I need a dummy O2 (O2 simulator)? I will NOT install a cat to accomodate my ECU's love affair with Al Gore or the EPA.

 

You can get a SCT tunner and use that to remove the after CAT O2 or you can just let the after CAT O2 just hang in the open air. A lot of Jeep guys just remove the after CAT O2 from the exhaust pipe and tuck it up behind a heat shield. Don't waist your money on the O2 simulators.