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Unread 01-28-2014, 11:34 AM   #1
iowajeepjoe
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5.2 Magnum / 318 to TJ Experienced help needed

My Jeep: 98 Sahara 300k miles
Things I've done to date: 4in rough country lift, Rear spring relocater, Front pucks (to even out front to rear), JB conversions mega short sye, Tattons Driveshaft, 8.8 rear end, 1in body lift, Boom proof MM, many other small things

THE TOPIC
I am wanting to put in a dodge magnum motor in place of the I6. Ive already read everything related to the topic i can find, but still have some questions (even more the deeper i dig into it) and could use some prior experience to help. Because as luck would have it i found a 94 5.2 dodge ram 1500 with 46rh.... FOR FREE!!! (cant beat that deal and it runs great) Plus I already have the motor and trans pulled.

FYI: 1994 was the first year that the 5.2 Magnum was made in the Rams.
The 98-01 Ram, Dakota, Durango would be best options due to the change of the OBDII systems in all 1998+ and also the change from the 46rh to the 46re in the Dodge line in 1997.
I do plan on using a junk yard 98 ecu and 98 wiring from something to keep the OBDII

Question #1 can anyone tell me if anything physically changed to the motor from 97 to 98 because of the OBDII change or was it just in the wiring harness and such?

Question #2 I know everyone talks about the work needed the wiring harnesses to get 98 Jeep and the 98 Dodge to talk and work well together. I already know where to find the drawing for each harness and how about to do it... BUT not looking forward to doing it and i can not and will not pay $700 to have it done
SO my question is... in 98 only Jeep made a Grand Cherokee with a 5.2 and 5.9.... so if i where to find a 98ZJ ecu and wiring harness, shouldn't that be plug and play in my 98 wrangler with a 5.2?

Question #3 Is the change from the 46rh to the 46re going to be something i can not overcome using a 98ecu? im thinking elec loop of some kind?

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Unread 01-28-2014, 04:29 PM   #2
jbryant
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I am not sure of the difference is OBDI and OBDII, possibly different sensors would have to be changed/ added (evap, O2, etc...) I think if you go with an OBDII computer and wiring harness you should replace the sensors on the motor to match. You should be able to find a V8 manual transmission ECU and maintain that 46rh. Do more research and ask on the bigger Magnum V8 Discussion thread here
http://www.jeepforum.com/forum/f9/wr...ssion-1365878/
I’m sure someone there has more insight on OBDI vs. OBDII.
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Unread 01-28-2014, 05:26 PM   #3
Wheelin98TJ
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I can only answer #2 - not plug and play.

Now that I got the easy one out of the way, someone else can take 1 and 3.
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Unread 01-28-2014, 08:47 PM   #4
LaddieHanus
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I am putting in a 95 318 into my YJ and I had investigated putting it in my TJ.

First of all you will need to convert the engine to OBDII. The dasboard in the TJ and 96+ Dodges are driven by the engine computer. I have also read that there are enough differences between 97 and 98 that you need to use a 98 to about 2000 harness and computer in your 98. As far as differences in the motors 94 to 98 all the sensors have different part numbers I am not sure if the throttle body is the same.

The transmission is a big issue, the 46rh (also known as a 518) has 2 computer inputs for torque converter lockup and to turn on the overdrive. In the 46re the shifting is done by computer and I think there are 8 wires going to the transmission. The newer computer will expect full transmission control and at the least will throw codes and and possibly not even run. You could use the 46rh by using a manual transmission computer and you can use toggle switches to control the torque converter lockup and overdrive. There is a way to automatically do it that the muscle cars guys use but I am not on the computer where I booked marked the website. I will update this post tomorrow.

FYI the magnum 5.2 came out in 1992 and was used in dakotas and Rams and in the 93 Grand Cherokee In 93 the 5.9 came out in Rams.94 was the year of the new body style for the Ram. Primary changes are revised cylinder heads and SMPI fuel injection vs the TBI 318 and 360.
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Unread 01-29-2014, 12:13 AM   #5
iowajeepjoe
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Thanks jbryant, i think ive read this one but long ago, so its still great as a re-read now that i know more about all the little details


Quote:
Originally Posted by Wheelin98TJ View Post
I can only answer #2 - not plug and play.

Now that I got the easy one out of the way, someone else can take 1 and 3.
Ok explain, i need more info then that... so the 98 Grand Cherokee with a 5.2 is not 100% plug and play, but is it easier to do the wiring from that starting point over mashing the 98 TJ and 98 Ram ones together... and if that not the issue what is?

And your right LaddieHanus in my setup i cant use the transmission so ill try to swap my 46rh for a 46re from a junk yard or someone
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Unread 01-29-2014, 08:23 AM   #6
Wheelin98TJ
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Quote:
Originally Posted by iowajeepjoe View Post
...Ok explain, i need more info then that... so the 98 Grand Cherokee with a 5.2 is not 100% plug and play, but is it easier to do the wiring from that starting point over mashing the 98 TJ and 98 Ram ones together... and if that not the issue what is?...
Grand Cherokee is loaded up with options.

I don't know if the wiring is any easier or not. I imagine it would be comparable.
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Unread 01-29-2014, 08:38 AM   #7
clintrivera
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It may be cheaper and easier to sell your free stuff and get a 96-98 5.2 then try to cobble together something that may or may not work. You'll be money ahead to do a swap that's proven rather than trying to invent something. Better yet, get a 5.9. I'm not sure the 5.2 is going to be worth the time unless you just want to swap to an auto.
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Unread 01-29-2014, 04:09 PM   #8
elmoe
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I have a 98 TJ with a 98 GC 5.9 46RE in it. I did the wire harness myself and after redoing it for a suspect problem I determined that doing the harness is not that bad. I used the GC harness and mated about 5-8 wires to the TJ harness. The 46RE harness was a plug and play. ( I have still not wired the OD switch). I would get a OBDII engine so all of the sensors would be plug and play. If you find a OBDII GC engine and want some information feel free to PM and I will provide a number. Several people answered questions for me so I will try and help if I can.
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