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Unread 12-03-2012, 12:26 PM   #1
Hitman72
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1988 MJ Comanche 
 
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Location: napa, ca
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new 88 comanche

Just purchased a 88 4.0L i6 (with an EGR system) 5-speed, 158*** miles.

Just was wondering what are a few of the first things to do to get the most out of the truck.

The previous owner overfilled the oil and it blew back into the air box and soaked the air filter (i could ring out the thing like a sponge it was so bad). Cleaned all the air hoses and new filter. Was going to pull off the throttle body off later and clean all the crap out. With this problem what else should a check.

Also what can i do about the EGR system, should i take it off? (i have looked around and it sounds like people are 50/50 on it)

I also noticed on the way home pretty bad gas mileage (not driven it much to get a good average) and know that the bad air filter was probably part of the problem but was wondering if there was any other things to check in regards to this problem.

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Unread 12-03-2012, 12:33 PM   #2
Tylerzap
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Change all the fluids, clean throttle body, Seafoam it, grease everything, check all vaccum hoses for cracks, and make sure they are connected in the right place, check tire pressure...

Humm... i cant think of anything else.
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Unread 12-03-2012, 12:38 PM   #3
Hitman72
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ya got all of that done, that is the first step for all cars.

I was wondering what is the second and third steps are.
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Unread 12-04-2012, 06:25 AM   #4
cruiser54
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Quote:
Originally Posted by Hitman72 View Post
ya got all of that done, that is the first step for all cars.

I was wondering what is the second and third steps are.
Click here. http://www.cherokeeforum.com/f51/cru...x-tips-153657/

I've included the most important one in this post.



Renix Ground Refreshing

The Renix era XJs and MJs were built with an under-engineered grounding system for the engine/transmission electronics. One problem in particular involves the multiple ground connection at the engine dipstick tube stud. A poor ground here can cause a multitude of driveabililty issues, wasted time, and wasted money replacing unnecessary components.

The components grounding at the dipstick tube stud are:

Distributor Sync Sensor, TCU main ground, TCU “Shift Point Logic”, Ignition control Module, Injectors, ECU main ground which other engine sensors ground through, Oxygen sensor, Knock Sensor, Cruise Control, and Transmission Sync signal. All extremely important stuff.

The factory was aware of the issues with this ground point and addressed it by suggesting the following:

Remove the nut holding the wire terminals to the stud. Verify that the stud is indeed tightened securely into the block. Scrape any and all paint from the stud’s mounting surface where the wires will attach. Must be clean, shiny and free of any oil, grease, or paint.

Inspect the wire terminals. Check to see that none of the terminals are crimped over wire insulation instead of bare wire. Be sure the crimps are tight. It wouldn’t hurt to re-crimp them just as a matter of course. Sand and polish the wire terminals until clean and shiny on both sides. Reinstall all the wires to the stud and tighten the nut down securely.

While you’re in that general area, locate the battery negative cable which is fastened to the engine block just forward of the dipstick stud. Remove the bolt, scrape the block to bare metal, clean and polish the cable terminal, and reattach securely.

Another area where the grounding system on Renix era Jeeps was lacking is the engine to chassis ground. There is a braided cable from the back of the cylinder head that also attaches to the driver’s side of the firewall. This cable is undersized for it’s intended use and subject to corrosion and poor connections at each end.

First off, remove the cable end from the firewall using a 15mm wrench or socket. Scrape the paint off down to bare metal and clean the wire terminal. Reattach securely.
Remove the other end of the cable from the rear of the head using a 3’4” socket. Clean all the oil, paint and crud from the stud. Clean the wire terminal of the cable and reattach securely.

A suggestion regarding the braided cable:
I prefer to add a #4 Gauge cable from the firewall to a bolt on the rear of the intake manifold, either to a heat shield bolt or fuel rail bolt. A cable about 18” long with a 3/8” lug on each end works great and you can get one at any parts store already made up. Napa has them as part number 781116.

A further improvement to the grounding system can be made using a #4 cable, about 10” long with 3/8” terminals at each end. Attach one end of this cable to the negative battery bolt and the other end under the closest 10mm headed bolt on the radiator support just forward of the battery. Napa part number 781115.



If you want to upgrade your grounds and battery cables in general, contact Jon at www.kelleyswip.com. He makes an incredible cable upgrade for a very reasonable price.


Revised 11-28-2011
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Quote:
Originally Posted by chris87xj View Post
If you own a Renix Jeep, you'll want to check this out. >

An index to over 25 write-ups can be found in Post #1.

Cruiser's Mostly Renix Tips
My Jeep Technical Photos

http://www.cherokeeforum.com/g/album/1725214
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Unread 12-04-2012, 08:56 AM   #5
Hitman72
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thanks for the info. I will check this out when i have the time. I am not having any of the major problems that were associated with what your said.



AND...... WHATS NEXT!!!
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Unread 12-04-2012, 10:05 AM   #6
97_4popper
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1990 MJ Comanche 
 
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Location: Guston, KY
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Above all, go over to comancheclub.com.
Everything you ever wanted to know about these trucks oer there.

good luck.
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Unread 12-04-2012, 10:12 AM   #7
Hitman72
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Haha ya I have already created am account. That's place is great.
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Unread 12-04-2012, 03:35 PM   #8
cruiser54
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Quote:
Originally Posted by Hitman72 View Post
thanks for the info. I will check this out when i have the time. I am not having any of the major problems that were associated with what your said.



AND...... WHATS NEXT!!!
The whole idea is to do those things so you WON'T have bigger problems later.
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Quote:
Originally Posted by chris87xj View Post
If you own a Renix Jeep, you'll want to check this out. >

An index to over 25 write-ups can be found in Post #1.

Cruiser's Mostly Renix Tips
My Jeep Technical Photos

http://www.cherokeeforum.com/g/album/1725214
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Unread 12-05-2012, 12:14 PM   #9
Hitman72
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agree

so the temp gauge wont go above about 130. My roommate (he is an XJ guy) think that the PO put in a 160 degree thermostat instead of the stock 160 degree one that should be in there.

is there anything else that you think would cause this.

also how can i check to make sure the gauge and wiring is right?
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Unread 12-05-2012, 03:42 PM   #10
cruiser54
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Only use 83501426 stat from the dealer. It's 195*. Perhaps you don't even have a stat in there.
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Quote:
Originally Posted by chris87xj View Post
If you own a Renix Jeep, you'll want to check this out. >

An index to over 25 write-ups can be found in Post #1.

Cruiser's Mostly Renix Tips
My Jeep Technical Photos

http://www.cherokeeforum.com/g/album/1725214
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Unread 12-05-2012, 09:28 PM   #11
Hitman72
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so i replaced the thermostat and it is running much hotter but the gauge is not working. Sitting at idle in a drive through the electric fan kicked on but the gauge was still only reading 210?

Took off the sending wire and crimped it to make sure, but still no difference. also when it was off i grounded it and saw the gauge max out.
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Unread 12-06-2012, 04:42 AM   #12
cruiser54
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Quote:
Originally Posted by Hitman72 View Post
so i replaced the thermostat and it is running much hotter but the gauge is not working. Sitting at idle in a drive through the electric fan kicked on but the gauge was still only reading 210?

Took off the sending wire and crimped it to make sure, but still no difference. also when it was off i grounded it and saw the gauge max out.
Two different sender/sensors.

The fan temp SENSOR is in the radiator and triggers the electric fan to come on abut 218*. The SENDER on the back of the head is for the gauge and you've addressed it nicely. Actually, both my MJ and XJ operate exactly like yours is acting. I think you're fine.
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Quote:
Originally Posted by chris87xj View Post
If you own a Renix Jeep, you'll want to check this out. >

An index to over 25 write-ups can be found in Post #1.

Cruiser's Mostly Renix Tips
My Jeep Technical Photos

http://www.cherokeeforum.com/g/album/1725214
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Unread 12-06-2012, 09:25 AM   #13
Hitman72
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1988 MJ Comanche 
 
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Quote:
Originally Posted by cruiser54 View Post
Two different sender/sensors.

The fan temp SENSOR is in the radiator and triggers the electric fan to come on abut 218*. The SENDER on the back of the head is for the gauge and you've addressed it nicely. Actually, both my MJ and XJ operate exactly like yours is acting. I think you're fine.
I understand that the two are separate systems, but my problem is that the fan kicks on but the gauge in the dash reads below the 218* mark. So the gauge in dash and the sensor for the fan are not reading the same temp. How do i resolve this, just replace the sensor sending unit, or is there a way to use a volt meter to test the gauge itself?

thanks for all the help. The truck is coming along nicely.
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Unread 12-06-2012, 02:52 PM   #14
cruiser54
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Quote:
Originally Posted by Hitman72 View Post
I understand that the two are separate systems, but my problem is that the fan kicks on but the gauge in the dash reads below the 218* mark. So the gauge in dash and the sensor for the fan are not reading the same temp. How do i resolve this, just replace the sensor sending unit, or is there a way to use a volt meter to test the gauge itself?

thanks for all the help. The truck is coming along nicely.
I'm sayuing it's normal. Temp sender is reading the 210* at the top rear of the head. The sensor is reading the 218* at the bottom of the radiator.
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Quote:
Originally Posted by chris87xj View Post
If you own a Renix Jeep, you'll want to check this out. >

An index to over 25 write-ups can be found in Post #1.

Cruiser's Mostly Renix Tips
My Jeep Technical Photos

http://www.cherokeeforum.com/g/album/1725214
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Unread 12-06-2012, 03:08 PM   #15
Hitman72
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1988 MJ Comanche 
 
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How for do you usually have to drive before up to normal temp? (Understand there are lots of variables, so just a general idea? )
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