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just got an 88 4.0 andf need to know what

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Old Jul 10, 2012 | 01:13 PM
  #1  
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From: lone pine ca
Year: 88 cherokee
Model: Cherokee
Engine: 4.0
Default just got an 88 4.0 andf need to know what

are the most common problems with these motors .i am putting in a new head gasket (but it doesnt look like it blew )i do have 2 plugs that look like they arent firing very well 3,6 . do the inhjectors go bad like in my old zr1s due to the new fuel breaching the coil sealing?? they all ohm put at 16.5. it looks like there is alot of black gunk in the intake passages . can one get trouble codes from these motors . any guidance would be greatly appreciated . as this is the wifes new toy and is on my buns to get it going .
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Old Jul 10, 2012 | 01:23 PM
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From: Colorful Colorado
Year: 1989
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Grounds on the renix machines especially an 88 are a common issue.
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Old Jul 12, 2012 | 12:23 PM
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From: lone pine ca
Year: 88 cherokee
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hope i dont sound too stupid ,but what is renix ????
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Old Jul 12, 2012 | 12:25 PM
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Renix is the name for the management system. Renix XJs are from 86 or 87-91.
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Old Jul 12, 2012 | 01:00 PM
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The crap stock injectors on those is are a fire hazard as well.

I'm having second thoughts on have gone with the703's. Fine for allot of people I suppose. My issue is I make allot of short trips. Complicated, but the way the computer uses default settings I might be running rich allot.

In my signature, you might be especially interested in the C-101 connector, and the ground cleanup deal Cruiser wrote..
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Old Jul 12, 2012 | 01:06 PM
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I didnt know 703s were the right injectors for the Renix models.

I thought they were different than the 703s because of the different flow rate of the Renix...
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Old Jul 12, 2012 | 01:22 PM
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Year: 1990
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Engine: 4.0 i6
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Originally Posted by Gee oh Dee
I didnt know 703s were the right injectors for the Renix models.

I thought they were different than the 703s because of the different flow rate of the Renix...
So what injector would be a good upgrade over stock??
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Old Jul 12, 2012 | 02:42 PM
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Originally Posted by Gee oh Dee
I didnt know 703s were the right injectors for the Renix models.

I thought they were different than the 703s because of the different flow rate of the Renix...
The "come away" I got was that although higher, it's still colse enough for the 02 to compensate. The stock being 18.6 lbs/sec, and the 703's 20 something I think, being within 10% might be OK. (Renix guys have passed smog with them).

BUT, I've been thinking, in open loop, before temp is reached, and it brings in the 02 sensor in, in closed loop, it's using the default pulse width with the higher flow rate...presto, your rich. I'm mean I'm wondering...seems to make sense to me. Then to exaborate things a little bit, it may well warm up a little more slowly being rich like that.

cherokeelaredo'90..Rockauto sells the (dreaded) Airtex, 4 hole 18.6 lb injectors. At least one poster returned his set when one didn't work. Then Precision Injectors offers ..stuff. Then Programbo here, I was thinking about contacting.

Renix...Renault + Bendix

Last edited by DFlintstone; Jul 12, 2012 at 02:46 PM.
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Old Jul 12, 2012 | 02:50 PM
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Originally Posted by bradszr1
can one get trouble codes from these motors .
No...the Renix ECU stores no codes, has no light. Really we need a meter to do much with it, (since it's not talking!)
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Old Jul 12, 2012 | 02:59 PM
  #10  
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I though Mustang 5.0 injectors were the best for Renix, but I could be wrong.
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Old Jul 12, 2012 | 03:01 PM
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Year: 1987
Model: Wagoneer
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Originally Posted by cherokeelaredo'90
So what injector would be a good upgrade over stock??
I used Bosch 973's from Precision Fuel Injectors and couldn't be happier.
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Old Jul 12, 2012 | 03:50 PM
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Well, Flintstone, why don't you give the new member a prioritized list of things to do to his Renix Jeep in order to wring the most reliability out of it? Preventative stuff that could be in your signature. I'm curious to see how you prioritize it.
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Old Jul 12, 2012 | 04:49 PM
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Because YOU are the pro with all those years on the floor at the dealership, and I don't think I've even SEEN a running 88! But hey, the C-101 and grounds gotta be about at the top?

(Under the hood I mean)
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Old Jul 12, 2012 | 04:51 PM
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the most common problems with these motors
They're tough as nails.
Expect some piston slap and lifter noise, both harmless.
The biggest problems seem to be overheating due to an old/neglected/worn out cooling system, wiring issues related to deteriorated grounds and harness wiring, and sensors failing as they age. Typical older vehicle stuff.
Invest in a nice digital multimeter if you don't already have one. It'll come in handy.
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Old Jul 12, 2012 | 04:54 PM
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Originally Posted by DFlintstone
Because YOU are the pro with all those years on the floor at the dealership, and I don't think I've even SEEN a running 88! But hey, the C-101 and grounds gotta be about at the top?

(Under the hood I mean)
I want you to take my write-up list and prioritize it or just prioritize a section we would call "So you got yourself a Renix Jeep..." for new owners.
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