Author Topic: Jeep 4.0 Injector Upgrade  (Read 409 times)

MiniVanMan

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Jeep 4.0 Injector Upgrade
« on: January 18, 2012, 07:06:42 PM »
There's a popular junk yard mod for the 4.0; swapping out the fuel injectors with ones from Neons and Caravans, as they have slightly higher flow.

The Neon injectors have 4 holes in the nozzle, whereas the stock 4.0 injectors have a SINGLE hole. The extra holes allow a wider spray, improving efficiency, if only slightly.

People who have done this upgrade have reported a small improvement in gas mileage (maybe 3 to 5 mpg.. not much, but every bit helps), and better throttle response.

Well, I ordered a set from a guy on cherokeeforum, and did the swap today. Results so far are a smoother idle and much better throttle response, but I'll have to wait until next fill up to gauge fuel mileage improvement.

I did this upgrade basically "just because".. it was on my list of things to do to the XJ.

Turns out to be a really GOOD thing that i did, because here is one of the old injectors:



Wasn't going to be much longer before that thing started leaking. Fire hazard there. I've heard of guys burning down their entire rigs because of a leaky injector, though usually it's the seals that leak from what I understand.

Onyx Dragon

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Re: Jeep 4.0 Injector Upgrade
« Reply #1 on: January 19, 2012, 12:44:23 AM »
I may have to look into this.  What kind of programming is required?  Will it work with an OBD-I 4.0?

MiniVanMan

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Re: Jeep 4.0 Injector Upgrade
« Reply #2 on: January 19, 2012, 07:32:21 AM »
The only thing required for the OBDII 4.0 was to hold he battery cables together for 30 seconds, then do a key on, headlights on 10 second cycle, then off, then start the engine. Clears the ECU memory so it can relearn the new fuel trim for the upgraded injectors.

Not sure about OBD1... but here's the write up on the installation. Says pretty much to do the same thing for both.

http://www.cherokeeforum.com/f2/703-784-injector-swap-write-up-66456/

Onyx Dragon

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Re: Jeep 4.0 Injector Upgrade
« Reply #3 on: January 19, 2012, 09:16:44 AM »
The only thing required for the OBDII 4.0 was to hold he battery cables together for 30 seconds, then do a key on, headlights on 10 second cycle, then off, then start the engine. Clears the ECU memory so it can relearn the new fuel trim for the upgraded injectors.

Not sure about OBD1... but here's the write up on the installation. Says pretty much to do the same thing for both.

http://www.cherokeeforum.com/f2/703-784-injector-swap-write-up-66456/

There was also a split run in 95, so I'm not sure which injectors I'd be running.  Probably the lower ones since it's OBD-I

87Warrior

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Re: Jeep 4.0 Injector Upgrade
« Reply #4 on: January 19, 2012, 06:36:12 PM »
Glad to hear the injectors did you some good Nick. This is something I have been wanting to do for a loooong time but have never got around to purchasing them.

Did you buy refurbished, new or used injectors?

MiniVanMan

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Re: Jeep 4.0 Injector Upgrade
« Reply #5 on: January 19, 2012, 07:00:32 PM »
Glad to hear the injectors did you some good Nick. This is something I have been wanting to do for a loooong time but have never got around to purchasing them.

Did you buy refurbished, new or used injectors?

Refurbished used injectors. If you're at all interested, talk to Programbo on cherokeeforum. He collects from the JY and cleans then tests them. Installs new o-rings... whatever else they need... then sells them.

Here's his "for sale" thread. http://www.cherokeeforum.com/f11/784-upgrade-fuel-injectors-110829/

1fastII

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Re: Jeep 4.0 Injector Upgrade
« Reply #6 on: January 29, 2012, 11:45:09 AM »
I just recently found out there is a mod like this for 86-96 Broncos/F150's. 5.0 Explorer injectors, with 4 holes vs one.