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Unread 05-14-2009, 01:27 PM   #1
MeWJWifeZJ
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98 4.0L getting the 99+ intake swap, vacuum routing?

Who has done this conversion before? Should I use the old injectors and wiring or splice the newer stuff in? Also, where do the vacuum lines get re-routed to? The tees are not in the same spots and I am unfamiliar with the types of Vacuum the 4.0L puts out.

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Unread 05-15-2009, 03:49 PM   #2
MeWJWifeZJ
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btt, hoping to do the swap this weekend.
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Unread 05-15-2009, 06:53 PM   #3
bucko132
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im new to zj's what is the advantige of doing this?
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Unread 06-01-2009, 08:15 AM   #4
MeWJWifeZJ
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20-35 HP increase, bump in torque, bump in MPG. The HP gain was documented in a thread on a dyno
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Unread 06-01-2009, 09:12 AM   #5
squashman702
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Quote:
Originally Posted by MeWJWifeZJ View Post
20-35 HP increase, bump in torque, bump in MPG. The HP gain was documented in a thread on a dyno
With supporting mods. The guy that gained this much over on Mallcrawlin had a pretty extensive build. It looks like 5 hp or so is expected if done without anything else.
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Unread 06-01-2009, 09:27 PM   #6
muddyjgc
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I did the upgrade on mine about a year ago, here is a pic of the new setup.

The pic explains most of it. I plugged the two outer ports on the ends of the intake and used the center port for the vac line that runs to the purge solenoid, by turning the rubber elbows you can get that line to work.
I also had to extend the wires that go to the Intake air temp sensor since the 99+ intake has the sensor on the opposite side of the throttle body.
The bracket that holds the hard fuel line that runs under the intake wont work with the new intake without being modified. I haven't gotten around to modifying mine, the fuel line seems to be fine without it.

I used all my old injectors, fuel rail, brackets, Intake temp sensor,and
throttle body.

You won't see much difference in performance, just a little more low end ummph. I saw no mileage increase.

If you have any questions give me a shout.

On Edit: I just realized that this thread is 1/2 a month old. Did you get your intake installed?





Last edited by muddyjgc; 06-01-2009 at 10:00 PM..
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Unread 06-01-2009, 09:31 PM   #7
elmer_fud
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I would say use the same injectors. I wouldn't be surprised if jeep changed the fuel rail pressure when they went to the WJ
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Unread 06-01-2009, 11:50 PM   #8
JrMechanic
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Quote:
Originally Posted by elmer_fud View Post
I would say use the same injectors. I wouldn't be surprised if jeep changed the fuel rail pressure when they went to the WJ
To use the WJ Injectors you need an adjustable regulator like the Hesco one.

muddyjgc: How much low end did it give you? Anything at highway speeds? I've been debating on doing it to mine for awhile now, I can get the intake from a friend but I need a power steering pump and bracket from a 96+ (I have a 93) so it would cost me over $100 to do the mod. For what it would cost me, I figure I could put out a little more coin and just slap a cam in...
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Unread 06-02-2009, 08:52 PM   #9
muddyjgc
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Quote:
Originally Posted by JrMechanic View Post
To use the WJ Injectors you need an adjustable regulator like the Hesco one.

muddyjgc: How much low end did it give you? Anything at highway speeds? I've been debating on doing it to mine for awhile now, I can get the intake from a friend but I need a power steering pump and bracket from a 96+ (I have a 93) so it would cost me over $100 to do the mod. For what it would cost me, I figure I could put out a little more coin and just slap a cam in...

Not a whole lot. Probably not over $100 worth of power. I seemed to have a little more pickup off the line. Mine only cost me $25 from pick-n-pull, and was a direct bolt-on.

The intake is supposed to be good for about 15 hp. Supposedly Jeep had to restrict the exhaust ports to make the 4.0 meet new emissions, at a cost of 15hp. So they redesigned the intake to flow better to get the hp back.
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