NAXJA Forums -::- North American XJ Association  

Go Back   NAXJA Forums -::- North American XJ Association > NAXJA Unibody Jeep Technical Forums > Jeep Cherokee XJ (1984 - 2001) > Modified Tech Discussion
HOME Member FAQ Sponsor Info Rules Bylaws E-Mail

Modified Tech Discussion Forum for Tech related discussion for Modified XJ's and MJ's.

Reply
 
Thread Tools Display Modes
  #1  
Old February 15th, 2017, 07:35
Spydie Spydie is offline
NAXJA Forum User
 
Join Date: Feb 2017
Location: Michigan
Posts: 3
1990 4.0 auto misfire at 1700rpm

About to pick up a 1990 comanche with a 4.0 auto in it but am leary as it has a slight misfire at 1700rpm. The engine was just rebuilt by an actual engine machine shop so its not a garage build. The engine was bored out .020", over sized pistons, new rods, has cleggs stage 1 cam and cleggs stage 2 head. The engine has maybe 50 miles on it after the rebuild so its still in its break in period. Am wondering before i get this, what might the general causes be? Would like to know how little or big of an issue it might be.

Edit: When i went and looked at the truck the engine would only misfire once. Owner says its a crap shoot on if it will happen or not any given day
Reply With Quote
  #2  
Old February 15th, 2017, 11:29
old_man's Avatar
old_man old_man is offline
NAXJA Member
 
Join Date: May 2003
Location: Loveland, Colorado
Posts: 15,303
Re: 1990 4.0 auto misfire at 1700rpm

My bet would be on an injector that dried out and is clogged, but before I bought anything I would do a wet/dry compression check. I would take my endoscope and look down the cylinders.

An oil assay should show you if there is any metal in the oil.

A question would be if they used any breakin lube on the cam before starting it up. The assay should show that up as long as they haven't done an oil change.
__________________
Tom Houston - Former Colorado Chapter President & Terminal Adrenaline Junkie
Loveland, Colorado
You're just jealous because the voices don't talk to you.
Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
1990 RENIX misfire backfire on acceleration BigRen90 OEM Tech Discussion 21 May 4th, 2015 12:07
1990 RENIX misfire backfire on acceleration BigRen90 OEM Tech Discussion 0 April 22nd, 2015 10:04
1989 MJ. 1100-1700RPM hesitation Joshooha OEM Tech Discussion 22 December 17th, 2014 21:11
1990 ECM (Auto vs Manual) want2belifted OEM Tech Discussion 5 April 27th, 2006 20:33


All times are GMT -7. The time now is 13:30.


Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
NAXJA and NAXJA logo's Copyright NAXJA. All content/images Copyright NAXJA 1999-2014