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Unread 06-05-2012, 06:36 PM   #1
ZeroGravity
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4 cylinder to 6 cylinder swap

I have a 1998 XJ, 2 door, 5 speed that is in very good shape. It has the 4 cylinder motor which was fine when I got it but I'm driving on the highway more often and to be honest I wish it would throw a rod so I don't have to use it any more. I'm getting 14 MPG (I get 16 in my lifted YJ, 4.0) and it's becoming such a pain in the *** to feed, I keep considering getting a small car like a Mini Cooper or a Subaru Impreza. Way off in the back of my head but the thought gets more prevalent each time I hit interstate 95.

The original clutch is beginning to slip. I don't like the AX5 much either so I would like to replace the engine and tranny with a 4.0/AX15 while I'm all up in the guts. So, I would like to know exactly what I would need to do to pull this off.

I have a budget of $1000 and I can do all the work myself. Thanks.

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Unread 06-05-2012, 09:33 PM   #2
lsmurphy
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2.5s will surprise you when you get it running as it should. I get 24-26 round town.




Buy another XJ, what you want to do isn't worth it in IMO.
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Unread 06-05-2012, 11:30 PM   #3
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http://www.jeepforum.com/forum/f9/2-...08/index4.html
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Unread 06-06-2012, 05:41 AM   #4
ZeroGravity
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Okay what do I do to get it running good?

Buying another XJ isn't practical because I like the 2 door five speed which are quite rare, at least around here.

I really muddled that first post. My concerns involves the wiring harness in relation to engine performance. If I get the motor from a TJ obviously the wiring harness from the same vehicle isn't going to simply plug in. Would it be possible to modify and use my current wiring harness? I don't know how to tell the computer that my Cherokee it has two more cylinders.
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Unread 06-06-2012, 02:23 PM   #5
lsmurphy
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Time to do some serious maintenance.

All your sensors need to be replaced.

Get rid of your air box.

Drop the cat.

Plugs, wires, caps..........

Go through your electrical.



I'll bet it has been neglected?
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Unread 06-06-2012, 03:25 PM   #6
buildin1XJ
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X1 on ISMURPHY above do the maintainance and be happy with it. I've done many engine swaps in 4.0s but would not consider the can of worms I would open trying to convert one. If you really want 4.0 buy a new to you Jeep.JMHO.
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Unread 06-06-2012, 03:55 PM   #7
Trons
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I don't know. I had a friend do the swap but mainly because he got tired of running out of power on hill climbs. He bought the donor vehicle for a good price because it had been wrecked and did most of the swap himself. The only time he needed help was pulling the old one out, putting the new one in and drinking beer.

Having said that, the donor vehicle was necessary. All the sensors, wiring, ect need to be swapped over. Once he got it running, it ran like a champ. He had the AX15 and loved the amount of power it had when coupled to the 4.0. I say, if you got the time, and the donor vehicle, do it.
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Unread 06-06-2012, 04:03 PM   #8
lsmurphy
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Yeah I really wasn't trying to discourage you on the face of your swap.......but.......

Donor is the way to go as computer and harness and linkages and mounts......radiator support and radiator........etc.......will all have to be swapped. Drive shafts......etc.


Your 98 must be real special to justify it.


Just don't think you will manage under your $1000 budget.


I'm also going to guess about 30-40 hours of labor to complete.
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Unread 06-06-2012, 08:16 PM   #9
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Find a wreck donor vehicle. Remove the front grill and heater radiator assembly. Try to remove the engine transmission and transfer case as 1 unit. Remove the wiring loom from the donor and replace it plug for plug. Work back forward replace all 4 cylinder parts with all six cylinder parts. Replace all of the ecm's with donor vehicle parts.
I will take time but in the end you will have the truck that you want.
I had a bunch of people telling me I couldn't put a blown 427 in a vega! Lol
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Unread 07-18-2012, 07:16 PM   #10
ZeroGravity
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Quote:
Originally Posted by lsmurphy View Post
Time to do some serious maintenance.

All your sensors need to be replaced.

Get rid of your air box.

I don't feel as though the air box restricts the engine enough to justify removing considering it offers very good water protection. I want to remove the "horn" that appears to draw cool air from below.

Drop the cat.

Cat is a new, high flow unit attached a full 2.5" custom downpipe and exhaust that terminates before the rear axle. I have a spark plug anti fouler in the o2 bung which turned my engine light out, what I'm not sure about is whether or not it's going to come back on when I take the cat off. Apparently it's not doing a whole lot but I need it to pass inspection.

Plugs, wires, caps..........

Plugs, wires and etc. need to be replaced.

Go through your electrical.

Electrical is fine.

I'll bet it has been neglected?

Not neglected, abused.
Replies in red.

I'd like to revisit this. The biggest inconvenience would be engine and tranny mounts, are the in the same spots or not?
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Unread 07-18-2012, 08:08 PM   #11
ibjeepin95
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4 cyl. XJ's are awesome. You can rev them to the moon. Keep it.
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Unread 07-18-2012, 08:28 PM   #12
ZeroGravity
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What does that mean?
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Unread 07-19-2012, 04:54 AM   #13
ibjeepin95
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Originally Posted by ZeroGravity View Post
What does that mean?
It means just what I said. Those little motors are hard to kill. You can rev on them all day.
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Unread 07-20-2012, 05:35 AM   #14
ZeroGravity
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I know what you meant...

Hondas rev real high and are hard to kill too, doesn't get me off thinking about driving one.
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