89 cherokee laredo problems. - 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 laredo problems.

Custom Axle Work at CCORRough Country Lift Kits and Parts!Swag Off Road BIG-HIT TJ-YJ Rear Bumper

Reply
Unread 03-07-2010, 09:27 PM   #1
blndreaper
Registered User
 
Join Date: Mar 2010
Location: VA
Posts: 6
89 cherokee laredo problems.

Working on a 89 Jeep Cherokee laredo inline 6 and we're having some problems. So here we go..
-The engine usually starts fine, but sometimes it will take a good amount of throttle input to get it started.

-Once started it will only run if you keep on the gas a little and even then it will still stall eventually.

-If left to idle it will have a very erratic idle and the tachometer is twitchy. Sometimes it jumps, sometimes it twitches and sometimes it slowly goes down while twitching.

-We are stumped. We have replaced the crankshaft position sensor, distributor cap and rotor, spark plug wires, and the coil.
We are thinking it is electrical because of the erratic tachometer readings.

Looking for help and any suggestions would be great! Thanks for your help.
Edit: I think I covered it all, but if you need more info let me know!


Last edited by blndreaper; 03-07-2010 at 11:50 PM..
blndreaper is offline   Reply With Quote
Unread 03-07-2010, 10:41 PM   #2
oderalxjlaredo
Registered User
2000 XJ Cherokee 
 
Join Date: Aug 2009
Location: Fairfax, VA
Posts: 395
Did you check the air filter?
__________________
--
by the thing that spins when you drive underneath
oderalxjlaredo is offline   Reply With Quote
Unread 03-07-2010, 10:42 PM   #3
blndreaper
Registered User
 
Join Date: Mar 2010
Location: VA
Posts: 6
Yup, air filter has been checked.
blndreaper is offline   Reply With Quote
Unread 03-07-2010, 10:56 PM   #4
coppertop71
Senior Member
 
coppertop71's Avatar
1990 XJ Cherokee 
 
Join Date: Jun 2004
Location: Vancouver, WA
Posts: 951
Maybe a vacuum leak. If the 89 has a IAC you could have a erratic motor in the IAC which could have a similar effect like a vacuum leak and the cause of the first item in your problems listed. I would look at all those little black plastic lines for cracks in the corners, check the intake manifold gasket by spraying carb cleaner and listening to the idle for any stalling or rises in RPM's.
__________________
Mods
2006 Jeep Wrangler X, 4.0 4:11 gears

'90 Cherokee XJ,W/'91 4.0L reman/ 3.5" RE lift, W/31" M/S tires, 4:11 Gears W/Speedo gear change/ Aluminum Coolant Tank
A/C Conversion/Home Built Roof Rack/K&N Box Filter
Derale 15" Rigid Radiator Fan PT# DER-17415, through Summit W/2"X5/8X5/8"" spacer

Jeep Pic's
coppertop71 is offline   Reply With Quote
Unread 03-07-2010, 11:25 PM   #5
talentjeep
Registered User
1987 XJ Cherokee 
 
Join Date: Oct 2009
Location: talent,or
Posts: 1,226
your IAC (idle accelerator controller) and TPS (throttle position sensor) are both located on the throttle body on your intake.

pull the electrical connectors and clean 'em. have a buddy work the gas and make sure the TPS is moving when the pedal does.

check this out for more sophisticated diagnostics --->Jeep Cherokee Engines - RENIX (non-HO) Engine Sensor Diagnostics

and check your CPS (crankshaft position sensor) too! it's on your bellhousing.
__________________
'87 XJ Pioneer with 32" KM2s, etc.
talentjeep is offline   Reply With Quote
Unread 03-07-2010, 11:48 PM   #6
blndreaper
Registered User
 
Join Date: Mar 2010
Location: VA
Posts: 6
We replaced the crankshaft position sensor this morning, it didn't help either.
We wont be able to get to the jeep for a couple days, so keep the suggestions coming and we will check them all! Thanks for your help!
If it does turn out to be something like a leak what would cause the tachometer to be so erratic? It even almost pegged once and the engine was off!


Note that it has been sitting for a couple months until we tried to run it the other day.
blndreaper is offline   Reply With Quote
Unread 03-08-2010, 05:36 AM   #7
cruiser54
Web Wheeler
 
cruiser54's Avatar
1990 MJ Comanche 
 
Join Date: Oct 2009
Location: Prescott, Arizona
Posts: 10,058
Remove,clean, scrape and polish the ground connections. One is at the engine dipstick tube and the other is from the back of the head to the driver side firewall. Clean 'em all. Your ECM relies on these connections to do it's job. I would also inspect for where the negative battery cable is connected and refresh that connection while you're at it.
cruiser54 is offline   Reply With Quote
Unread 03-08-2010, 07:14 AM   #8
tjwalker
It's the crank sensor!
 
tjwalker's Avatar
1999 XJ Cherokee 
 
Join Date: Nov 2007
Location: Central Minnesota, MN
Posts: 8,434
1. Freshen all electrical grounds as our groundskeeper mentioned
2. Be sure battery is solid. LOAD TESTING is the only conclusive way to tell. You can have a battery strong enough to start the engine but marginal enough to trip up the engine management system.
3. Test AND adjust your throttle position sensor (the TPS is adjustable on an 89)
4. Test fuel pressure with a gauge at the fuel rail
5. Ignition control module is still in play, even though coil has been replaced
__________________
99 Cherokee, 4.0 AW4, NP242
Past Jeeps: 49 Willys, 81 Scrambler, 88 Comanche
Without "data", all you have is an opinion!
tjwalker is offline   Reply With Quote
Unread 03-08-2010, 08:08 AM   #9
blndreaper
Registered User
 
Join Date: Mar 2010
Location: VA
Posts: 6
I forgot to mention the battery was also replaced.
We will keep all these in mind here in a couple days when we can check it.
blndreaper is offline   Reply With Quote
Unread 03-12-2010, 12:23 AM   #10
blndreaper
Registered User
 
Join Date: Mar 2010
Location: VA
Posts: 6
Well, problem solved for now at least.

We replaced the positive battery terminal and then we noticed the ground terminal was loose enough to just slip off. We still don't know why it was like that because we have checked it, but any ways we fixed that and reattached a vacuum line. Thanks everyone for your help!
blndreaper is offline   Reply With Quote
Unread 03-12-2010, 04:33 AM   #11
tjwalker
It's the crank sensor!
 
tjwalker's Avatar
1999 XJ Cherokee 
 
Join Date: Nov 2007
Location: Central Minnesota, MN
Posts: 8,434
Quote:
Originally Posted by cruiser54 View Post
Remove,clean, scrape and polish the ground connections. One is at the engine dipstick tube and the other is from the back of the head to the driver side firewall. Clean 'em all. Your ECM relies on these connections to do it's job. I would also inspect for where the negative battery cable is connected and refresh that connection while you're at it.
Cruiser54 gets the cookie!

Chalk up another one for "grounds". Often overlooked.

Glad you got it running.
__________________
99 Cherokee, 4.0 AW4, NP242
Past Jeeps: 49 Willys, 81 Scrambler, 88 Comanche
Without "data", all you have is an opinion!
tjwalker is offline   Reply With Quote
Unread 03-12-2010, 04:52 AM   #12
cruiser54
Web Wheeler
 
cruiser54's Avatar
1990 MJ Comanche 
 
Join Date: Oct 2009
Location: Prescott, Arizona
Posts: 10,058
I'm glad to hear it's running. Good job. But, even though everything seems well on the "ground front", I think you should still perform the freshening of the other grounds that we suggested as a matter of maintenance. It WILL save you from future problems.
cruiser54 is offline   Reply With Quote
Unread 03-12-2010, 07:46 PM   #13
blndreaper
Registered User
 
Join Date: Mar 2010
Location: VA
Posts: 6
I will definitely clean up those grounds!
blndreaper is offline   Reply With Quote
Unread 03-12-2010, 10:27 PM   #14
talentjeep
Registered User
1987 XJ Cherokee 
 
Join Date: Oct 2009
Location: talent,or
Posts: 1,226
let us know how it turns out!
__________________
'87 XJ Pioneer with 32" KM2s, etc.
talentjeep is offline   Reply With Quote
Reply
Thread Tools


Suggested Threads





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.