NAXJA Forums -::- North American XJ Association  

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

OEM Tech Discussion Forum for OEM (Original Equipment) or stock XJs and MJs.

Reply
 
Thread Tools Display Modes
  #1  
Old April 5th, 2019, 17:37
Jradkins Jradkins is offline
NAXJA Forum User
 
Join Date: Apr 2019
Location: Mebane NC
Posts: 1
Acceleration problem

I have an 89 xj sport and have just recently replaced the head gasket and got a valve job. I also have performed a complete tuneup and service including fuel filter. I had a rough idle problem to start with before the head gasket was replaced and now Iím having a problem while driving. When accelerating it starts at low end fine and when the throttle is half open starts to hesitate and skip but when I put it to the floor it clears out and runs seamingly well. I have put a new map sensor, iac valve, cleaned throttle body and put all new plugs ,wires, rotor button ,cap , fuel filter and air filter. Even added Lucas to the oil and gas and still have the same problem. Also all the vacuum lines and pcv valve have been cleaned or replaced. Any ideas?
Reply With Quote
  #2  
Old April 6th, 2019, 05:35
CJR CJR is offline
NAXJA Forum User
 
Join Date: May 2005
Location: PA
Posts: 187
Re: Acceleration problem

I'd look for an intake manifold leak; i.e. a cracked intake manifold, a poor sealing intake manifold gasket, etc. It appears to be "loading up" with too much fuel because the computer is seeing a lean condition(i.e. too much air into the engine). When you floor the pedal, it clears out the excess fuel and then runs properly for awhile until it loads up with fuel again.

Best regards,

CJR
Reply With Quote
  #3  
Old April 6th, 2019, 08:50
8Mud's Avatar
8Mud 8Mud is offline
NAXJA Forum User
 
Join Date: Sep 2003
Location: Central Germany
Posts: 8,477
Re: Acceleration problem

On my 89 (I bought used) somebody had replaced the water pump and routed the harness that comes up from the O2 sensor, knock sensor and engine temp. sensor too close to the exhaust manifold and it was melting. It was really hard to see in there, the melted section was really hard to spot.

A year or so later mine developed what I call a 2000 rpm buck, it bucked when slowly accelerating at or around 2000-2200 RPM, ran fine at lower RPM's or higher RPM's (or more pedal). Turned out to be the O2 sensor.
Reply With Quote
  #4  
Old April 6th, 2019, 09:03
jbeintherockies's Avatar
jbeintherockies jbeintherockies is offline
NAXJA Forum User
 
Join Date: Aug 2014
Location: Aurora, Colorado
Posts: 54
Re: Acceleration problem

Not to be a smart ass, but what Jeep Cherokee doesn't have an acceleration problem?


Reply With Quote
  #5  
Old April 7th, 2019, 09:27
JeepNoob JeepNoob is offline
NAXJA Forum User
 
Join Date: Oct 2014
Location: Pueblo, Colorado
Posts: 376
Re: Acceleration problem

Quote:
Originally Posted by jbeintherockies View Post
Not to be a smart ass, but what Jeep Cherokee doesn't have an acceleration problem?


You're new here, aren't you?

Saw a buddy of mine at the store one day, we get to s***ing the bull about his ride (old-school Pontiac Grand Prix with a factory 3.1 turbo V6, VERY rare and pretty cool) and mine (P.O.S. XJ with a 4.0 and a slush-box AW4) I comment that the thing's pretty fast for a 4x4 SUV. He calls shenanigans and wants a race. Now I don't condone or recommend shenanigans like this on public roadways, but hey, I'm an XJ-guy.

Rolling start, I let my buddy catch up until we're about even and doing I dunno, 20, 25 MPH. Then we both give 'er. Damned if we both weren't even all the way to 55 or 60. After that, aerodynamics seemed to kick in, and he pulled away from me. But to quote Enzo Ferrari "Aerodynamics are for people who don't know how to build an engine." Plenty of engine options out there to make an XJ go faster- stroker kits, blowers, turbos, LS-swaps, sometimes a combination there-of.
Reply With Quote
  #6  
Old April 8th, 2019, 12:09
Rob Mayercik's Avatar
Rob Mayercik Rob Mayercik is offline
NAXJA Member #920
 
Join Date: Jun 2002
Location: NJ, U.S.A.
Posts: 2,255
Re: Acceleration problem

Don't forget, Enzo also said "Jeep is America's only real sports car"...
__________________
1992 Cherokee Laredo: "A wonderful balance of grace and rust"
1984 Dodge Omni
2002 Volkswagen Jetta GLS TDI
Reply With Quote
  #7  
Old April 12th, 2019, 18:21
old_man's Avatar
old_man old_man is offline
NAXJA Member
 
Join Date: May 2003
Location: Loveland, Colorado
Posts: 15,635
Re: Acceleration problem

What you describe could be a ton of things. A cracked header could be screwing with the O2 or the O2 could be bad.

You could have a slightly clogged CAT.

You could have a flakey CPS. I had one that limited the rpms to only 2000.

I have even had a coil that could not handle load or rpms over 2500

Have you done a plug reading? Post up pix.

How old are your plug wires?

Double check the distributer wiring/firing order.

Long shot, clogged fuel filter (monitor fuel pressure with gauge)
__________________
Tom Houston - Former Colorado Chapter President , Terminal Adrenaline Junkie, and Rocket Scientist
Loveland, Colorado My teardrop build
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
clunk upon acceleration projectTK Modified Tech Discussion 10 August 22nd, 2009 17:43
No Acceleration brandonmcnulty OEM Tech Discussion 17 March 6th, 2006 10:49
Acceleration Problem: Update #2 BSD OEM Tech Discussion 7 December 12th, 2005 03:21
Acceleration Bog Down surfmon OEM Tech Discussion 1 September 9th, 2005 10:46
Acceleration Problem JNG 92XJ OEM Tech Discussion 4 February 28th, 2005 18:46


All times are GMT -7. The time now is 10:01.


Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
NAXJA and NAXJA logo's Copyright NAXJA. All content/images Copyright NAXJA 1999-2014