Go Back   Jeep Garage - Jeep Forum > Jeep Platform Discussion > Grand Cherokee - WJ > Troubleshooting/Problems

Join Jeep Garage Today
Reply
 
Thread Tools Display Modes
 
  #1  
Old 12-13-2012, 05:51 PM
New Member
 
Join Date: Dec 2012
Posts: 4
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0
Heyoh!! is on a distinguished road
Question 1999 Grand Cherokee misfire

First would like to say hello to the forum. As stated in the title I am having a misfire on my 4.7 GC. My " misfire " happens around 60-70 miles an hour on highways. I give it a certain position on the pedal and it gives me a lean pop through the airbox. If I am starting out and have the same pressure on the pedal no problems or pops. It seems to be only in higher gears. I have had computers hooked up while on test drives and results are pretty much lean 75% of time. I have replaced the following parts

All plugs, coils, TPS, IAC, fuel filter, checked fuel pressure when problem happens, nothing changes when it does. I have also NO codes at all. Light does work if codes are present. Replaced the O2 sensors as well. I have read about the Exhaust valves going bad...Possible? Runs smooth as can be otherwise. Even when it pops just have to get off of the throttle so problem stops. All help would be thankful.
__________________

__________________
Reply With Quote
  #2  
Old 12-13-2012, 07:13 PM
Frango100's Avatar
Premium Member

My Jeep: 2004 4.7L WJ
 
Join Date: Dec 2009
Location: Brazil
Posts: 4,914
Thanks: 9
Thanked 92 Times in 87 Posts
Rep Power: 525867
Frango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond repute
Re: 1999 Grand Cherokee misfire

If you really have a misfire, you should have a DTC set. Did you verify this, eventhough the check engine light is off?
Did you see the fuel trims of both banks, to see if there is a difference between the 2 banks?
__________________

__________________
Frank

JEEP Grand Cherokee 4.7 Lmtd 2004
HID 8000K in low and fog / Quad Squad member
KYB Gas-a-Just shocks / Pirelli Scorpion ATR 245/65/17 - Transgo reprogramming shiftkit.

VW Beetle 2.0 TSI 2013
My new toy
Reply With Quote
  #3  
Old 12-13-2012, 09:11 PM
New Member
 
Join Date: Dec 2012
Posts: 4
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0
Heyoh!! is on a distinguished road
Re: 1999 Grand Cherokee misfire

thanks for the response Frango... Answers are yes and yes. I also would like to add I did a smoke test to look for vacuum leaks as well as a top throttle cleaning with seafoam. My O2 sensors were not Chrysler but the more I am reading the more I am wanting to sway towards a valve spring or something? But who am I to say. Any tests to check valve springs or can they be checked without removing the heads? Thanks again
__________________
Reply With Quote
  #4  
Old 12-14-2012, 06:01 AM
Frango100's Avatar
Premium Member

My Jeep: 2004 4.7L WJ
 
Join Date: Dec 2009
Location: Brazil
Posts: 4,914
Thanks: 9
Thanked 92 Times in 87 Posts
Rep Power: 525867
Frango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond reputeFrango100 has a reputation beyond repute
Re: 1999 Grand Cherokee misfire

The only test i know of for the valve springs is with a special spring force tester. You donīt have to remove the head for that, but only the springs you want to test.
But about the fuel trims, where they equal on both banks?
__________________
Frank

JEEP Grand Cherokee 4.7 Lmtd 2004
HID 8000K in low and fog / Quad Squad member
KYB Gas-a-Just shocks / Pirelli Scorpion ATR 245/65/17 - Transgo reprogramming shiftkit.

VW Beetle 2.0 TSI 2013
My new toy
Reply With Quote
Reply

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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
2005 Grand Cherokee 3.7 misfire PKCherokee Troubleshooting/Problems 10 10-12-2013 09:05 AM
1999 4.7 Grand Cherokee Misfire Heyoh!! Troubleshooting/Problems 1 12-13-2012 05:49 PM
2005 Grand Cherokee Cylinder 1 misfire 4.7 waldnerstev Troubleshooting/Problems 2 08-30-2012 12:18 PM

Powered by vBadvanced CMPS v3.2.3

All times are GMT -5. The time now is 06:07 AM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Copyright 2012 - JeepGarage.Org
The Jeep Grand Cherokee Owners Community