1987 xj shuts off

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Mar 19, 2013 | 05:59 PM

#16

67 GMC

Senior Member

Joined: May 2012

Posts: 925

Likes: 6

From: Fort Erie, CANADA

Year: 1987

Model: Cherokee

Engine: 4.0

Quote:

Originally Posted by cruiser54

What the hell is the loose connection you posted about earlier? Did you fix it?

Yeah-I'm not sure what that silver box thingy is about. Maybe a picture from him would help in case there's a remote starter or something like that installed.

Mar 19, 2013 | 06:34 PM

#17

cruiser54

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Joined: Aug 2011

Posts: 43,971

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From: Prescott, Az

Year: 1990

Model: Cherokee (XJ)

Engine: 4.0

Quote:

Originally Posted by 67 GMC

Yeah-I'm not sure what that silver box thingy is about. Maybe a picture from him would help in case there's a remote starter or something like that installed.

You can't walk past a loose connection and continue trying other stuff....

Mar 19, 2013 | 07:52 PM

#18

DFlintstone

CF Veteran

Joined: Aug 2011

Posts: 10,489

Likes: 24

From: Nor-Cal Coast

Year: 90,84

Model: Cherokee

Engine: 4.0,2.5

Quote:

Originally Posted by jdjonesdr

Some days it would do it 3-4 times within a mile or two, other times I'd go days without it happening. (Try to troubleshoot that!!)

They even had a fix called the "Sutter Maneuver" or something like that, which involved bypassing the ECU by cutting two wires on the harness of the ECU, and connecting them together, which eliminated the ECU.

I did it, and went from being incredibly exasperated to surprisingly pleased from one minute to the next. The difference was like night and day.

Since I bought my 90' XJ and have been working on it and driving it .

Likely off topic here, (or not). Course you can't "bypass the ECU" but I'm curious. Got any further info? Possibly a ground was re routed? (from "ECU grounding, to actual ground).

Komby, the valve cover is not your best ground. It shouldn't actually touch the block. Yea, it has a bunch of little bolts that connect it....anyway likely you are OK, just sayen.. just find less than an ohm or so wherever. Also I watched my CPS work till it dipped under .3. Still worked, but long starts, crummy idle. My .02 is over .35 might be fine. Just me though. Napa #css980 or Mopar.

You can swap your 2'nd and 4'th relay. See if that helps. If it's a connection to the (second) fuel pump relay, or the relay it's self, no harm in trying the AC relay there. Fix the loose wire!!!

Last edited by DFlintstone; Mar 19, 2013 at 07:54 PM.

Mar 20, 2013 | 05:58 AM

#19

jdjonesdr

Seasoned Member

Joined: Oct 2012

Posts: 328

Likes: 5

From: Dominican Republic

Year: 1990

Model: Cherokee

Engine: inline 6

Quote:

Originally Posted by DFlintstone

Likely off topic here, (or not). Course you can't "bypass the ECU" but I'm curious. Got any further info? Possibly a ground was re routed? (from "ECU grounding, to actual ground).

I was close(been a long time).

The correct term is nutter bypass. Here's a couple of threads from sister forums that describes it.

http://www.4x4wire.com/jeep/tech/ele...jn-ignition99/

http://www.jeepforum.com/forum/f12/p...bypass-476720/

The posters refer to it as eliminating the ECU, but of course, that's not accurate. I can tell you it seemed like I installed a new motor in my jeep after I did it.

I mentioned it because my YJ did the same thing as the OP's Cherokee. I'm guessing a similar procedure doesn't exist for our beloved Cherokees...

Last edited by jdjonesdr; Mar 20, 2013 at 06:00 AM.

Mar 20, 2013 | 08:23 AM

#20

kombi

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Newbie

Joined: Feb 2013

Posts: 9

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Model: Cherokee

Yes I fixed that before I posted it

I don't know what the part is. It is the silver box that the power cable running from the alt to this silver box(has multiple fusable links connected too it) it then runs to the pos battery terminal. So I basicly had a loose power cable . That is fixed.

I noticed after I disconnected the battery and ran new power cables (resetting ecu) feels slower and the trans felt like it was slipping or couldn't decide on a gear.. I'm thinking maybe the TPS? does that inform the trans of the Throttle position?

Last edited by kombi; Mar 20, 2013 at 09:10 AM.

Mar 20, 2013 | 08:29 AM

#21

kombi

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Newbie

Joined: Feb 2013

Posts: 9

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Model: Cherokee

I'm not ignoring loose connections. I clean them with brake cleaner cleaner (non connectors), wire brush then clean of all corrosion and clear all paint till parts are shining. Connectors I open up clean with electric cleaner, wire brush and use pick's to clean them till all tabs are spotless, i then apply dialectric greese and make sure they seal good and some i add zipties to make sure the connection is tight.. Or if beyond cleaning as in the case of my injector plugs i solderd, and used heat shrink to wire in newer clean connectors. Also resistance tested to make sure the solder was good. Silver box is factory.. a regulator or something. Its next to the battery/relays

Last edited by kombi; Mar 20, 2013 at 09:09 AM.

Mar 20, 2013 | 09:05 AM

#22

kombi

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Joined: Feb 2013

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Model: Cherokee

as for the valve cover not being a good ground. i have a two new ground straps coming off the same location to the body. so its not grounding threw the valve cover bolts to the block. i think i have gone over kill with the grounds if thats possible lol..

i have added.. body to valve cover, batt to body, vc to block, block to body. was debating the alt to body or alt to battery aswell.

Any harm in adding alt power cable directly to the positive battery terminal? the power regulator is in the alt on these correct? i have no external regulator and testing the output with all accessorys on its at 14.3v so i would assume there is no harm.

also i read somewhere that you can put a later model 1990 ecu in the older renix rigs. is this correct? found a 1990 for $60 i was going to try in it. but wanted to make sure first.

Mar 20, 2013 | 04:33 PM

#23

cruiser54

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Joined: Aug 2011

Posts: 43,971

Likes: 1,579

From: Prescott, Az

Year: 1990

Model: Cherokee (XJ)

Engine: 4.0

Quote:

Originally Posted by kombi

as for the valve cover not being a good ground. i have a two new ground straps coming off the same location to the body. so its not grounding threw the valve cover bolts to the block. i think i have gone over kill with the grounds if thats possible lol..

i have added.. body to valve cover, batt to body, vc to block, block to body. was debating the alt to body or alt to battery aswell.

Any harm in adding alt power cable directly to the positive battery terminal? the power regulator is in the alt on these correct? i have no external regulator and testing the output with all accessorys on its at 14.3v so i would assume there is no harm.

Need a fuse in that line to the battery. Leave yours as it is or upgrade to 5-90's cables.

also i read somewhere that you can put a later model 1990 ecu in the older renix rigs. is this correct? found a 1990 for $60 i was going to try in it. but wanted to make sure first.

An 89 or 90 ECU will work. Not night and day, but better. Just make sure if you have an auto trans, you get one from an auto trans.

FWIW, Renix eCUs do not reset.

Mar 20, 2013 | 07:15 PM

#24

mikesignal

Senior Member

Joined: Aug 2009

Posts: 914

Likes: 14

From: north carolina

Year: 2000

Model: Cherokee

Engine: 4.0

FWIW my old XJ was cutting off. You'd be driving along, then bam-dead. Nothing. It was completely dead. Long story short and 3 shops later I got a refurb computer for $180?? I think. this was 9 years ago. Fixed the issue.

Mar 20, 2013 | 09:29 PM

#25

DFlintstone

CF Veteran

Joined: Aug 2011

Posts: 10,489

Likes: 24

From: Nor-Cal Coast

Year: 90,84

Model: Cherokee

Engine: 4.0,2.5

Quote:

Originally Posted by jdjonesdr

.
The correct term is nutter bypass. Here's a couple of threads from sister forums that describes it.
http://www.4x4wire.com/jeep/tech/ele...jn-ignition99/
http://www.jeepforum.com/forum/f12/p...bypass-476720/

Thanks~. I've been getten after the "cobwebs" in my carbourated 84 2.5. It never seemed right even when it was right. (took plenty of dough to smog it).
Q. Will this help my 4.0L engine?
A. NO! This has been asked a few times. Don't even think about trying this on a 4.0L engine. The 4.0 fuel injection system is totally different and far superior to the 4.2L engines carbureted system. The 4.0 needs no such ignition modification to perform well, but some aftermarket ignition modules may be used to increase performance.
Q. Will this work on my early XJ with the carbureted 2.5L engine?
A. The wiring portion is the same, but the XJ carburetor is very different. I have never attempted this on an XJ 2.5 L, so I don't know how well it works. If you decide to try a modification like this, you do so at your own risk, but drop me a note and let me know what happened.

Mar 21, 2013 | 05:48 AM

#26

jdjonesdr

Seasoned Member

Joined: Oct 2012

Posts: 328

Likes: 5

From: Dominican Republic

Year: 1990

Model: Cherokee

Engine: inline 6

I guess I should have just said "Check the ECU" instead of trying to explain the whole situation I went through with my other jeep.. LOL

Mar 21, 2013 | 06:46 AM

#27

cruiser54

::CF Moderator::

Joined: Aug 2011

Posts: 43,971

Likes: 1,579

From: Prescott, Az

Year: 1990

Model: Cherokee (XJ)

Engine: 4.0

Ya know, this may be worth a try:

Cruiser’s Renix ECU Connector Refreshing

Many times when other fixes have failed, it becomes necessary to eliminate the ECU to harness connections as a cause. This requires removing the ECU.

Up under the dash, to the right of the steering column is the ECU. It is held in by three 10mm headed bolts to a bracket. It’s most easily removed using a ratcheting wrench but a socket will work.

Once you get the ECU down, unplug the two harness connectors from it. Visually inspect the connectors and pins.

Using a good quality electronics cleaner, liberally spray both of the harness ends and the ECU pin area.

Now, take a small pick or a dental tool and go to the harness connectors. Using the tool, tweak each female receptacle in the harness plugs so they will grasp the ECU pins more tightly.

Plug the harnesses back on to the ECU and reinstall it. I usually only use two of the bolts because the third is a bear.

Revised 07/11/12

Mar 23, 2013 | 01:23 PM

#28

kombi

Thread Starter

Newbie

Joined: Feb 2013

Posts: 9

Likes: 0

Model: Cherokee

ok i was driving it last night after work. i had the heat on and lights. about a block away from my house i noticed the lights Dim and i had been watching the Battery charge gauge the whole time.. it dipped down to 8 and the jeep started missing. i had the battery tested its good. i have triple checked every pos battery cable and ground i can find. there all good . the battery is good but could this dip in power cause the stall? im thinking because my CPS reads so low still that the dip in power that i think the failing alt is causing might be the issue?

going to check all the alt wiring for the charging curcit and if i dont find anything replace the alt and see how that goes

Mar 23, 2013 | 01:36 PM

#29

DFlintstone

CF Veteran

Joined: Aug 2011

Posts: 10,489

Likes: 24

From: Nor-Cal Coast

Year: 90,84

Model: Cherokee

Engine: 4.0,2.5

The Alt is a suspect alright. Make sure it's not just a loose belt! Radi had a great tip, the pulley will be hot if it's slipping..Here there are a couple places that will check them free. Bummer Btw! You can win this one!