89 cherokee issue - JeepForum.com
Search  
Sign Up   Today's Posts
User: Pass: Remember?
Advertise Here
Jeep Home Jeep Forum Jeep Classifieds Jeep Registry JeepSpace Jeep Reviews Jeep Gallery Jeep Clubs Jeep Groups Jeep Videos Jeep Events Jeep Articles
Go Back JeepForum.com > Models > Jeep Cherokee & Comanche Forums > XJ Cherokee Technical Forum > 89 cherokee issue

The Original 3/8" Ruffstuff Diff Cover!Building a Bumper?Introducing MONSTALINERô UV Permanent DIY Roll On Bed Line

Reply
Unread 06-10-2013, 12:50 AM   #1
jordanj222
Registered User
1989 XJ Cherokee 
 
Join Date: Jun 2013
Location: mchenry, il
Posts: 7
89 cherokee issue

hi there new to the forum, from northen IL. anyways i have an 89 jeep cherokee 2 door limited with 206,xxx on her. shes been a big project.
added a 2" lift to the front and added 2 leafs to the rear with a 4" rear lift.
removed the abs module and replaced with a vacuum booster.
and other minor things.
recently ive been have issues.
first i need to dial in the master better but thats my trial and error.
i ve been have a idle issue and it keeps changing . ive replaced the iac , spark plugs, tps. the idle surges sometimes between 100rpms to 800rpms. then at other times it idles fine, other times will idle high like 1200rpms.
checked for vacuum leaks and didnt find any , egr seems to be moving fine, has a aftermarket cone filter on it until i can save up for a snorkel.
i cleaned off the grounds under the hood and now its worse again . voltage at idle is between 14.2v and 14.4v. oil pressure (per gauge which im sure isnt accurate) 10 and 40. but sometime when it has good idle pressure will be at 30 . and other times will be at 40 and surge.
the car was sitting for a year before i bought it , and has been sitting for 2 years since ive owned it but have started it up now and then inbetween. the other day finally drove it to work and put over 80miles on her. idle was good on most of the trip but after 20miles idle got rough again.
any help for where to go further would be nice.

i dont know if its on the form but would be nice to see a ignition system upgrade on aa budget post or somewhere where i can see my options for all types of ignition system upgrades. and other engine upgrades ... did i miss it?

jordanj222 is offline   Reply With Quote
Unread 06-10-2013, 07:22 AM   #2
cruiser54
Web Wheeler
 
cruiser54's Avatar
1990 MJ Comanche 
 
Join Date: Oct 2009
Location: Prescott, Arizona
Posts: 9,796
Start here:

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, failed emission tests, and wasted money replacing components unnecessarily.

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.

For those of us with Comanches, it’s very important to remove the driver’s side taillamp assembly to access the ground for the fuel pump. Remove the screw holding the black ground wire. Scrape the paint from the body and corrosion from the wire terminal. Reattach securely.

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 03-04-2013
__________________
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
Refresh*Connections*Before*Replacing*Components
cruiser54 is offline   Reply With Quote
Unread 06-10-2013, 07:23 AM   #3
cruiser54
Web Wheeler
 
cruiser54's Avatar
1990 MJ Comanche 
 
Join Date: Oct 2009
Location: Prescott, Arizona
Posts: 9,796
Then do this:


RENIX TPS ADJUSTMENT

Before attempting to adjust your TPS be sure the throttle body has been recently cleaned. It's especially important that the edges of the throttle butterfly are free of any carbon build-up.

IMPORTANT NOTE: With the Key OFF, and using the positive (red) lead of your ohmmeter, probe the B terminal of the flat 3 wire connector of the TPS. The letters are embossed on the connector itself. Touch the black lead of your meter to the negative battery post. Wiggle the wiring harness where it parallels the valve cover and also over near the MAP sensor on the firewall. If you see more than 1 ohm of resistance, or fluctuation in your ohms reading, some modifications to the sensor ground harness will be necessary. The harness repair must be performed before proceeding. I can provide an instruction sheet for that if needed.

MANUAL TRANSMISSION:
RENIX manual transmission equipped XJs have only a flat three-wire TPS mounted on the throttle body and it provides data input to the ECU. It has three wires in the connector and they're clearly embossed with the letters A, B, and C. Wire "A" is positive. Wire "B" is ground. Key ON, measure voltage from "A" positive to "B" ground by back-probing the connectors. Note the voltage reading--this is your REFERENCE voltage. Key ON, back-probe the connector at wires "B" and "C". Measure the voltage. This is your OUTPUT voltage. Your OUTPUT voltage needs to be seventeen percent of your REFERENCE voltage. For example: 4.82 volts X .17=.82 volts. Loosen both T-20 Torx screws attaching the TPS to the throttle body and rotate the TPS until you
have achieved your desired output voltage. Tighten the screws carefully while watching to see that your output voltage remains where it is supposed to be. If you can't achieve the correct output voltage, replace the TPS and start over.

Sometimes, after adjusting your TPS the way outlined above, you may experience a high idle upon starting. If that happens, shut the engine off and reconnect your probes to B and C. Start the engine and while watching your meter, turn the TPS clockwise until the idle drops to normal and then rotate it back counterclockwise to your desired output voltage.

AUTOMATIC TRANSMISSION: RENIX automatic transmission equipped XJs have a TPS with two connectors. There is a flat three-wire connector, same as the manual transmission vehicles have, and it is tested the same as the manual transmission equipped vehicles, as outlined above—FOR ALL ENGINE MANAGEMENT RELATED ISSUES.

However, the automatic TPS also has a square four-wire connector, clearly embossed with the letters A,B,C, and D. It only uses three wires and provides information to the Transmission Control Module. THIS SQUARE FOUR WIRE CONNECTOR IS USED FOR TRANSMISSION/SHIFTING RELATED ISSUES ONLY. Key ON, measure voltage between "A" positive and "D" ground. Note the voltage. This is your REFERENCE voltage. Back-probe the connector at wires "B" and "D". Measure the voltage. This is your OUTPUT voltage. Your OUTPUT voltage needs to be eighty-three percent of your REFERENCE voltage. For example 4.8 volts X .83=3.98 volts. Adjust the TPS until you have achieved this percentage. If you can't, replace the TPS and start over. So, if you have an automatic equipped XJ your TPS has two sides--one side feeds the ECU, and the other side feeds the TCU.
FOR AUTOMATIC TRANSMISSION RELATED ISSUES: Check the square four-wire connector side of the TPS.
If you have ENGINE ISSUES check the flat three-wire connector side of the TPS.

For those with a MANUAL TRANSMISSION--the TPS for the manual transmission XJs is stupid expensive. You can substitute the automatic transmission TPS which is reasonably priced.
Revised 09-22-2012
__________________
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
Refresh*Connections*Before*Replacing*Components
cruiser54 is offline   Reply With Quote
Unread 06-10-2013, 10:54 AM   #4
jordanj222
Registered User
1989 XJ Cherokee 
 
Join Date: Jun 2013
Location: mchenry, il
Posts: 7
Yea I didn't fix the ground on the drivers side , ill try that and see what happens ...
jordanj222 is offline   Reply With Quote
Unread 06-10-2013, 05:03 PM   #5
cruiser54
Web Wheeler
 
cruiser54's Avatar
1990 MJ Comanche 
 
Join Date: Oct 2009
Location: Prescott, Arizona
Posts: 9,796
Quote:
Originally Posted by jordanj222 View Post
Yea I didn't fix the ground on the drivers side , ill try that and see what happens ...
Do it all and don't take any shortcuts.
__________________
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
Refresh*Connections*Before*Replacing*Components
cruiser54 is offline   Reply With Quote
Unread 06-18-2013, 09:17 AM   #6
jordanj222
Registered User
1989 XJ Cherokee 
 
Join Date: Jun 2013
Location: mchenry, il
Posts: 7
Now I've noticed that it does it only in drive and reverse , its a weird idle surge and makes the the jeep wanna surge forward when sitting at a lite, unless I'm minor on the throttle
jordanj222 is offline   Reply With Quote
Unread 07-05-2013, 03:54 PM   #7
jordanj222
Registered User
1989 XJ Cherokee 
 
Join Date: Jun 2013
Location: mchenry, il
Posts: 7
Btw check the sensors and are in spec of what's stated
jordanj222 is offline   Reply With Quote
Unread 07-05-2013, 05:54 PM   #8
cruiser54
Web Wheeler
 
cruiser54's Avatar
1990 MJ Comanche 
 
Join Date: Oct 2009
Location: Prescott, Arizona
Posts: 9,796
Quote:
Originally Posted by jordanj222 View Post
Btw check the sensors and are in spec of what's stated
Please translate this into English for us.
__________________
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
Refresh*Connections*Before*Replacing*Components
cruiser54 is offline   Reply With Quote
Unread 09-16-2013, 02:00 PM   #9
jordanj222
Registered User
1989 XJ Cherokee 
 
Join Date: Jun 2013
Location: mchenry, il
Posts: 7
Lol was the egr , so issue fixed thanks
jordanj222 is offline   Reply With Quote




Jeep, Wrangler, Cherokee, Grand Cherokee, and other models are copyrighted and trademarked to Jeep/Chrysler Corporation. JeepForum.com is not in any way associated with Jeep or the Chrysler Corp.