what is a H.O.??????
04-29-2009, 02:15 PM
#2
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Year: 1987
Model: Cherokee
Engine: 4.0 liter RENIX I-6, DIY Cold Air Intake, 2.5 FM Exhaust, 3 Core Radiator
Well, if you're refering to a 4.0 liter "H.O." engine. It is the 2nd generation (if you will) of the 4.0 inline 6 cylinder engine made by Jeep with some upgrades over the previous "Renix" Jeep 6 cylinder engine. The HO started being produced in the 91 year model. Basically what you have is an upgraded fuel injection system and new computer (ECU). You have an ugraded (open type) cooling system. An upgraded better flowing exhaust manifold. It produces 190 advertised HP compared to 170 advertised HP from the previous "Renix" motor. I'm sure there are other differences that I don't know that the other guys will add. I have an HO motor in my 91 XJ and that thing is bombproof!!! I love it. Best HP and MPG, combination, from one motor I've ever owned.
04-29-2009, 02:33 PM
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alright!thank you both! now i can focus on what im reading and not what H.O. means. thanks again. i have a 94 grand, kinda blind when it comes to 4 liters, i do love a I6 though!
04-29-2009, 07:49 PM
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Year: 1988
Model: Cherokee
Engine: AMC242
There are three basic generations of the 242ci six...
1987-1990 (RENIX.) This is the first iteration of the control system, the first iteration of the cylinder head, and is considered "pre-OBD." Typical computer interrogators won't work, and it doesn't "Store" or "Throw" codes. Just about anything can be troubleshot with a DMM (you do require an analogue meter for a couple of tests.)
1991-1995 (HO, OBD-I.) First HO generation, used Chrysler control electronics. Responds to a Chrysler OBD-I code reader (each of the Big 3 had their own version of OBD-I.)
1996-2007 (HO, OBD-II.) Second-generation HO, can be further divided along the 1999/2000 line (1996-1999 for XJ, 1996-1998 for ZJ/TJ. 2000-2001 XJ, 1999-2007 WJ/WK/TJ. Yeah, it gets a little hairy...) The later version of that had the COP/DIS ignition system (Coil On Plug/Distributorless Ignition system,) and the 1999-2001/2002 heads are the ones prone to cracking between the #3 and #4 cylinders. Seems to be about even odds on whether your head cracks or not - the easiest fix is to get a 2002-2007 #0331 head.
Cylinder head numbers (to narrow down what you're looking at):
#2686 - 1987-1990
#7120 - 1991-1995
#0630 - 1996-1999
#0331 - 1999-2007. Distinctive in that it is the only head that has the bosses for attachment of the coil rail.
The casting ID number can usually be found over the #3/#4 exhaust ports, driver's side, outside of the valve cover. It is a raised cast feature, rather than a depressed stamped one.
1987-1990 (RENIX.) This is the first iteration of the control system, the first iteration of the cylinder head, and is considered "pre-OBD." Typical computer interrogators won't work, and it doesn't "Store" or "Throw" codes. Just about anything can be troubleshot with a DMM (you do require an analogue meter for a couple of tests.)
1991-1995 (HO, OBD-I.) First HO generation, used Chrysler control electronics. Responds to a Chrysler OBD-I code reader (each of the Big 3 had their own version of OBD-I.)
1996-2007 (HO, OBD-II.) Second-generation HO, can be further divided along the 1999/2000 line (1996-1999 for XJ, 1996-1998 for ZJ/TJ. 2000-2001 XJ, 1999-2007 WJ/WK/TJ. Yeah, it gets a little hairy...) The later version of that had the COP/DIS ignition system (Coil On Plug/Distributorless Ignition system,) and the 1999-2001/2002 heads are the ones prone to cracking between the #3 and #4 cylinders. Seems to be about even odds on whether your head cracks or not - the easiest fix is to get a 2002-2007 #0331 head.
Cylinder head numbers (to narrow down what you're looking at):
#2686 - 1987-1990
#7120 - 1991-1995
#0630 - 1996-1999
#0331 - 1999-2007. Distinctive in that it is the only head that has the bosses for attachment of the coil rail.
The casting ID number can usually be found over the #3/#4 exhaust ports, driver's side, outside of the valve cover. It is a raised cast feature, rather than a depressed stamped one.
04-29-2009, 08:26 PM
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04-30-2009, 10:15 AM
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Year: 1987
Model: Cherokee
Engine: 4.0 liter RENIX I-6, DIY Cold Air Intake, 2.5 FM Exhaust, 3 Core Radiator
Sheesh, and I always thought a Ho was what I used to turn the dirt in my garden...LOL.
12-25-2009, 11:23 PM
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Well, if you're refering to a 4.0 liter "H.O." engine. It is the 2nd generation (if you will) of the 4.0 inline 6 cylinder engine made by Jeep with some upgrades over the previous "Renix" Jeep 6 cylinder engine. The HO started being produced in the 91 year model. Basically what you have is an upgraded fuel injection system and new computer (ECU). You have an ugraded (open type) cooling system. An upgraded better flowing exhaust manifold. It produces 190 advertised HP compared to 170 advertised HP from the previous "Renix" motor. I'm sure there are other differences that I don't know that the other guys will add. I have an HO motor in my 91 XJ and that thing is bombproof!!! I love it. Best HP and MPG, combination, from one motor I've ever owned.
THanks
ET3 Vasterling (formerly of USS Yellowstone)
12-25-2009, 11:30 PM
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Year: 2001
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Engine: 4.0
12-26-2009, 12:10 AM
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Model: Cherokee
HP Upgrade to HO level
Well, if you're refering to a 4.0 liter "H.O." engine. It is the 2nd generation (if you will) of the 4.0 inline 6 cylinder engine made by Jeep with some upgrades over the previous "Renix" Jeep 6 cylinder engine. The HO started being produced in the 91 year model. Basically what you have is an upgraded fuel injection system and new computer (ECU). You have an ugraded (open type) cooling system. An upgraded better flowing exhaust manifold. It produces 190 advertised HP compared to 170 advertised HP from the previous "Renix" motor. I'm sure there are other differences that I don't know that the other guys will add. I have an HO motor in my 91 XJ and that thing is bombproof!!! I love it. Best HP and MPG, combination, from one motor I've ever owned.
I have 160,000 on jeep xj
4 liter automatic, with factory class 3 hitch.
Upgrades recently: Edelbrock titanium header. K&N Cold air intake system. Kumho 6 ply 30.9 tires.
Is there a list of items you could send me that I would need to address and or replace to increase hp? short of motor overhaul, what can be done to get more power, ie replace stock throttle body with aftermarket unit. etc?
Any suggestions, links and possible part numbers would be appreciated.
Thank you
I was East coast, USS Yellowstone during Desert Shield Desert Storm and other actions. Now disabled vet.
Please email me if you have any recommendations.
Thank you sir