As the title says, I have a 91 dakota sport with 318 LA engine. My engine is shot and needing a rebuild, but
Recently I acquired a 318 magnum from a 99 ram 1500 complete with engine wiring harness and ecm. I'm thinking of swapping it in.

Just wondering what all the swap takes.

Is there any issues with it due to the obd1 system in my current setup to the obd 2 setup in the 99 ram?

Is the engine, computer and such different from the 99 rams 318 and say a 95 dak 318?

Any tips info and pointers would be appreciated. Thanks

 

Engine is the same, as far as I know.

The ECU, OTOH, will be radically different - the 1995 will be SBEC, the 1996 and up are JTAC, and don't directly swap. You're looking at rewiring the truck completely.

Also, it's still radically different than your 1991.

You MIGHT be able to get away with a 1996 Dakota 5.2 harness and ECU.

Or actually, a 1992+ setup; although if you're rewiring, I'd go whole hog with the 1996 ECU and engine bay harness, and grab the inside harness, get the OBDII compatibility, and the programmability that the JTAC had, so that you get the maximum benefit.

RwP

 

I'm totally fine rewiring, as I have alot of other mods I'm going to work on as well. Just trying to wrap my brain around everything involved before I jump into it

I have the ecu for the 99 and the engine harness.

So what other harness/wiring will I need? If at all possible I want to keep my stock dash and gauges of the 91.

I deffinately would like the perks of obd2 especially since so far this engine, ecu, and engine harness was the perfect price!

 

Heh. Rotsaruck. By 1999, the ECU was driving all the gauges; I'd opt for finding a 1996.

You'll have to rewire the firewall blockhead connector to suit the 1999; also, the internal wiring is different (the 1999, again, uses an internal bus to talk from the ECU to the instrument cluster; the 1991 is basic and all but the tach is driven off sensors / sending units from the motor; the speedometer is driven off the transmission via a mechanical cable; and the tachometer gets two pulses per revolution from the ECU.)

Again, you'd do MUCH better finding a 1992-1996 Dakota donor; and ideally 1996 to get OBDII (the last few years drove the speedometer off the VSS signal, but you can still use the current design and the mechanical drive.)

And with the retrofit costs, it's not the perfect price even if they pay you to take it *grins*

RwP

 

The engine harness and ecu was totally free, runs and what not. That's why I was considering dropping it in.

So clearly it's way too much work to use this setup.

Is the engine still the same to the extent I can just get different sensors (if plugs are different) a harness from a 96 (or pre if I stay with obd1) and the proper ecm. (I was reading somewhere doing that with the 96 obd2 engine to make it obd1 and having to change intake due to having egr but can't find that post atm)

If I stay with a 318 mag that is obd1 is that a pretty straight forward swap with the wiring?

 

You may have to find and swap in a proper oil pan - I've read that both yes, and no, the RAM oil pan swaps with the Dakota. I haven't measured, so don't know.

Past that - yes, if you go for a 1996 donor, you should be able to swap in the OBDII wiring and ECU and get OBDII. You'll have to swap some of the inside wiring though (to get the OBDII plug amongst other items.)

If however you pick up a 1992-1995 donor, from my notes, you may have to repin a few wires at the bulkhead connector but overall it'll swap in. Engine bay harness may be all you need with the ECU.

The sensors should be the same. Also, the wiring on the motor should be very close; at worst, pull the engine harness off the donor truck *grins*

RwP

 

There IS one other choice - get the heads cross drilled to take the LA intake, and then swap on your current TBI intake.

I don't know how well that will work, but it seems like you'd get something between the Magnum free breathing performance and the stock TBI performance.

RwP

 

The oil pan won't be a concern at all with some of the other mods I'm doing. (Sas... actually it's more of a complete frame swap)

I really don't want to go get another engine if I don't have to. Especially if mechanically this 99 ram 318 is the same as the 92-96 dak 318 mag.

I was reading somewhere that the wire plugs for sensors are different that's why I mentioned having to change sensors.

So would the 96 even being obd2 will work with my 91 dash and gauges. (I'm trying to keep everything cab/box/interior wise close to stock)

Honestly at this point I'm leaning more towards keeping it obd1 after reading many posts about it.

At that point my bulkhead should work, with exception of possibly having to repin a few wires??

So I'll need the intake, any sensors that are needed for an obd1 and the obd1 318 mag harness and ecm correct? And still be able to basically use the long block I have from the 99 ram?

Also how many o2 sensors does the 318 mag (obd1) use. My current LA setup has a single in the y-pipe

 

Ahem.

I meant the 96 donor to avoid swapping the motor - the 96 is OBDII, but uses the same gauge cluster as the 1995. The main difference is that around 1994 Chrysler switched to an electronic speedometer (110MPH top), whereas your 1991 uses a mechanical. Strangely enough, the 1991 drive setup will work fine with your 1991 cluster, as long as you can put the VSS/cable combo into the transmission you use.

(The 1996 also switched to the electronic transmissions, that may make a difference.)

And it's not OBD/OBDII that makes the difference; they changed the dash connection for 1997 due to it being a new generation.

Now here is where it gets a bit confusing - you're mixing OBD/OBDII and LA/Magnum. There were several years OBD Magnum (1992-1995).

Your motor, however, is an LA.

To use your current intake and keep your current ECU, you'll have to get the heads redrilled to take a LA intake.

You can't just bolt your LA heads on; there's no oil gallery to lube the rocker shaft, so your engine life will be in the sub-100 (probably sub-1!) mile range.

There's more info at www.magnumswap.com and www.hughesengines.com .

(I'd read that Magnum Swap website several times; it's not perfect, but it does a great job of describing what some of the problems will be.)

As to the OBD Magnum O2 usage ... for 1995, the factory service manual shows one. Don't know about 1992-1994, but would be willing to bet it's the same.

RwP

 

I didn't want to know if my LA stuff transfered over. I want to make sure the earlier magnum intake and such will cross over to the 99 rams intake and so one...

Make sure there isn't any differences between the year ranges for the engine itself.

Like I just noticed this fuel system is return less for the 9 rams... are the early dak 318 mags, this way still or did they have a two line (return) fuel setup as my current engine had.