Replacing Fuel Injector
08-11-2014, 11:19 AM
#1
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Year: 1999
Model: Cherokee
Engine: 4.0
Replacing Fuel Injector
I noticed I had a new crack yesterday! (haha, sorry, couldn't resist).
CF posts lead me to understand that this is a fuel injector, although I'm not clear if it's a "boot" to the injector or "the" injector. Mine looks to be cracked (green arrow). I'm guessing it is very recent b/c I definitely would've noticed it before.
I don't know where this issue falls on the "immediacy" scale to fix, otherwise, I don't think the xj is showing any new weird symptoms (unless that exhaust at the red arrow doesn't normally register 350 degrees on an IR thermometer after a short drive - if that is normal, then it JUST got my attention and freaked me out).
IT is my DD and I'm hoping to make (an unusual) 150 RT mile roadtrip tomorrow . . .
So, I found THIS https://www.cherokeeforum.com/f51/in...ap-4-0l-92149/ (credit dukie564).
Questions - Are the injectors individually replaceable, provided the other ones look ok? Or is it desirable to just do them all anyway? (another write-up said the injectors could be pulled out and cleaned with carb cleaner, then Vaseline the Orings on re-insertion?)
If replacement is indeed my answer, recommendations on brands is appreciated. I don't mind paying a bit more, so long as I get what I pay for. The "other" kids can eat mac-n-cheese for a bit
CF posts lead me to understand that this is a fuel injector, although I'm not clear if it's a "boot" to the injector or "the" injector. Mine looks to be cracked (green arrow). I'm guessing it is very recent b/c I definitely would've noticed it before.
I don't know where this issue falls on the "immediacy" scale to fix, otherwise, I don't think the xj is showing any new weird symptoms (unless that exhaust at the red arrow doesn't normally register 350 degrees on an IR thermometer after a short drive - if that is normal, then it JUST got my attention and freaked me out).
IT is my DD and I'm hoping to make (an unusual) 150 RT mile roadtrip tomorrow . . .
So, I found THIS https://www.cherokeeforum.com/f51/in...ap-4-0l-92149/ (credit dukie564).
Questions - Are the injectors individually replaceable, provided the other ones look ok? Or is it desirable to just do them all anyway? (another write-up said the injectors could be pulled out and cleaned with carb cleaner, then Vaseline the Orings on re-insertion?)
If replacement is indeed my answer, recommendations on brands is appreciated. I don't mind paying a bit more, so long as I get what I pay for. The "other" kids can eat mac-n-cheese for a bit
08-12-2014, 08:08 AM
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Year: 1984
Model: Cherokee
Engine: 4 cyl
The cracked part is part of the injector (see here: http://www.completecherokee.com/prod-858.htm as that shows the entire body and the seal). Yes, you want to coat the o-ring seal before reinstalling. I would replace them all while you are in there. Exhaust temps can be in that range, but I'd suspect that cylinder is running lean and that's causing the exhaust to be hotter there.
08-12-2014, 03:08 PM
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Year: 90,84
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Engine: 4.0,2.5
You probably want to up-grade to 4 hole injectors. Not sure for your 99 but something like 703's I think. You might contact Programbo here on the forum and/or search "injector upgrade" There are a number of options.
08-12-2014, 07:00 PM
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Year: 1999
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I use Bosch 789's. They came from a 2000 Chrysler T & C, 3.3 Liter V6, flex fuel motor. 4 port nozzle.
Did use Ford XFE-C4B's for awhile but they ran a little too lean. The 789's are dead nuts.
If you want the OEM blue tips Motorman. com has rebuilt ones for sale. He lists them on Evilbay. Blue tips are part number 4854181.
Did use Ford XFE-C4B's for awhile but they ran a little too lean. The 789's are dead nuts.
If you want the OEM blue tips Motorman. com has rebuilt ones for sale. He lists them on Evilbay. Blue tips are part number 4854181.
08-12-2014, 07:25 PM
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Year: 1994 1993
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Oh my..So many things to reply to in this thread...... First off yes that is a crack and a bad one. The '99+ XJ injectors are very prone to cracking. It won't cause any fuel to leak but the '99+ XJs are prone to "heat soak" where the heat of the engine will cause fuel problems so having this opening on an injector can cause a problem in this area. You can replace just the one but I have found that if ones cracked in most cases they all are. The others might just be hairline cracks but they are probably there. If you do go to a salvage yard and grab another 04854181 just make sure it's not cracked and replace the o-rings and as mentioned lube them up before reinstalling.
If you decide to upgrade to the 4 hole ones the number you want is the Bosch 0280155784. You CAN use the 789's as mentioned but they aren't a great choice as they have an angled spray. Basically they spray like in this crappy diagram I made:
This is fine if they are in the motor they were designed for since it has slant heads but the problem with using them in an XJ is that part of the spray will hit the edge of the intake manifold. They seem to work ok but I don't know what the long term effect of the fuel spray hitting the intake may have as far as carbon build up etc.
If you decide to upgrade to the 4 hole ones the number you want is the Bosch 0280155784. You CAN use the 789's as mentioned but they aren't a great choice as they have an angled spray. Basically they spray like in this crappy diagram I made:
This is fine if they are in the motor they were designed for since it has slant heads but the problem with using them in an XJ is that part of the spray will hit the edge of the intake manifold. They seem to work ok but I don't know what the long term effect of the fuel spray hitting the intake may have as far as carbon build up etc.
Last edited by Programbo; 08-12-2014 at 07:42 PM.
08-13-2014, 02:26 AM
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Year: 1999
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Wow, Thanks a ton. Got through several more injector upgrade threads since my OP - helpful, but a little overwhelming with the choices/opinions, so I really appreciate having the guess work taken out of my shopping trip. And I totally dig learning why/how things work- especially with allegedly "crappy" diagrams haha so thanks Programbo!
I'm feeling pretty prepared for this one (I think Shakespeare called that bravado)
*EvilBay* - haha CCKen!
I'm feeling pretty prepared for this one (I think Shakespeare called that bravado)
*EvilBay* - haha CCKen!
08-13-2014, 07:54 AM
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Oh my..So many things to reply to in this thread...... First off yes that is a crack and a bad one. The '99+ XJ injectors are very prone to cracking. It won't cause any fuel to leak but the '99+ XJs are prone to "heat soak" where the heat of the engine will cause fuel problems so having this opening on an injector can cause a problem in this area. You can replace just the one but I have found that if ones cracked in most cases they all are. The others might just be hairline cracks but they are probably there. If you do go to a salvage yard and grab another 04854181 just make sure it's not cracked and replace the o-rings and as mentioned lube them up before reinstalling.
If you decide to upgrade to the 4 hole ones the number you want is the Bosch 0280155784. You CAN use the 789's as mentioned but they aren't a great choice as they have an angled spray. Basically they spray like in this crappy diagram I made:
This is fine if they are in the motor they were designed for since it has slant heads but the problem with using them in an XJ is that part of the spray will hit the edge of the intake manifold. They seem to work ok but I don't know what the long term effect of the fuel spray hitting the intake may have as far as carbon build up etc.
If you decide to upgrade to the 4 hole ones the number you want is the Bosch 0280155784. You CAN use the 789's as mentioned but they aren't a great choice as they have an angled spray. Basically they spray like in this crappy diagram I made:
This is fine if they are in the motor they were designed for since it has slant heads but the problem with using them in an XJ is that part of the spray will hit the edge of the intake manifold. They seem to work ok but I don't know what the long term effect of the fuel spray hitting the intake may have as far as carbon build up etc.
I never realized the 789's had an angled spray like you illustrate. Did you observe this in a see-through test box? By the looks of the location of the injector nozzles the angled spray may actually contact the upper surface of the intake port (if this is the angle of spray).
I guess it's back to blue tips or the XFE-C4B's.
Intake:
Closeup of intake ports/nozzle locations:
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08-14-2014, 11:35 AM
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You're not thinking of indexing spark plugs are you?
With fuel injectors with a straight out spray pattern what indexing is there to do?
BTW: Programbo is spot on concerning 789 injectors having an angled spray pattern. I checked with Rob Haack at Motor Man Fuel Injection and he says the 789's spray in a 30 degree bent angle.
With fuel injectors with a straight out spray pattern what indexing is there to do?
BTW: Programbo is spot on concerning 789 injectors having an angled spray pattern. I checked with Rob Haack at Motor Man Fuel Injection and he says the 789's spray in a 30 degree bent angle.
08-14-2014, 09:32 PM
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I actually discovered the angled spray by accident since I gathered a bunch of 789's because on paper they looked like the perfect substitute for the 784's which were getting harder to find. As part of my cleaning/testing process I always open the injectors and spray starting fluid through them to see the spray pattern and I saw the first 789 I tested sprayed a bit off to the side. I thought it was still just a tad dirty or clogged as that's what dirty injectors do sometimes but when the second and third and forth etc all sprayed the same way...Well. But if you want better replacement that is easy to find look for the bright lime green 0280156007 injectors in the newer 3.3L Caravans. They are plentiful in junkyards and you get 6 from one vehicle and the flow isn't far off of stock '99+ XJ injectors. They are also a 4 hole spray.
08-15-2014, 05:46 AM
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Glad Rob helped clear it up for you. I've done a lot of business with him over the years although he wouldn't know me under this name. I actually discovered the angled spray by accident since I gathered a bunch of 789's because on paper they looked like the perfect substitute for the 784's which were getting harder to find. As part of my cleaning/testing process I always open the injectors and spray starting fluid through them to see the spray pattern and I saw the first 789 I tested sprayed a bit off to the side. I thought it was still just a tad dirty or clogged as that's what dirty injectors do sometimes but when the second and third and forth etc all sprayed the same way...Well.
But if you want better replacement that is easy to find look for the bright lime green 0280156007 injectors in the newer 3.3L Caravans. They are plentiful in junkyards and you get 6 from one vehicle and the flow isn't far off of stock '99+ XJ injectors. They are also a 4 hole spray.
I actually discovered the angled spray by accident since I gathered a bunch of 789's because on paper they looked like the perfect substitute for the 784's which were getting harder to find. As part of my cleaning/testing process I always open the injectors and spray starting fluid through them to see the spray pattern and I saw the first 789 I tested sprayed a bit off to the side. I thought it was still just a tad dirty or clogged as that's what dirty injectors do sometimes but when the second and third and forth etc all sprayed the same way...Well. But if you want better replacement that is easy to find look for the bright lime green 0280156007 injectors in the newer 3.3L Caravans. They are plentiful in junkyards and you get 6 from one vehicle and the flow isn't far off of stock '99+ XJ injectors. They are also a 4 hole spray.
08-15-2014, 07:29 AM
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But if you want better replacement that is easy to find look for the bright lime green 0280156007 injectors in the newer 3.3L Caravans. They are plentiful in junkyards and you get 6 from one vehicle and the flow isn't far off of stock '99+ XJ injectors. They are also a 4 hole spray.