Multiple Misfires - Check Engine Light - 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 > Multiple Misfires - Check Engine Light

XHD Heavy-Duty Hood Latches for JK and TJ available at OcoSYE Kits from CCOR! 706-207-4140Stainless Steel Door Hinge Pins

Reply
Unread 06-11-2012, 10:02 PM   #1
noxj
Registered User
2001 XJ Cherokee 
 
Join Date: May 2012
Location: New Orleans, LA
Posts: 16
Multiple Misfires - Check Engine Light

I may need a mad scientist here. Check engine light has been on for a couple of days. Code was 1-3-5 misfiring. So i changed the spark plugs. Still had the light and the same code. Changed the coil pack (its an 01) and the light is still on.


Also There is a hint of a fuel odor when i first start it up. At first I was thinking this was a surge in pressure from the pump at start up so I checked my fuel lines. All the connections under the hood were fine and that's where the smell was coming from. That led me to the EEV filter and it was clean.

So now what I'm thinking is I have two problems. My temp gauge is clogged up or my fuel filter is clogged. Maybe there is also a crack in my exhaust somewhere letting out the unburnt fuel from the misfires?

Anyone have any experience this far in the ignition system?
Thanks in advance
-Noah

noxj is offline   Reply With Quote Quick reply to this message
Unread 06-11-2012, 10:26 PM   #2
CJ7-Tim
Real Jeeps have dents.
 
CJ7-Tim's Avatar
2000 XJ Cherokee 
 
Join Date: Apr 2002
Location: out in the garage - Minneapolis, Minnesota
Posts: 21,820
Exactly what CEL codes did you download ? When exactly, and under what conditions, is it mis-firing ? What brand and part number spark plugs did you install ?

If you smell fuel under the hood, you have a fuel leak. Check the fuel rail, the fuel lines, and the injector o-rings.
__________________
.

Between 2009 when Obama took office, and 2013, median annual household incomes have fallen by more than $2,100.

Progressive Liberalism: Bringing you new Healthcare ideas so wonderful, they have to include mandatory participation ......

Originally Posted by Ronald W. Reagan: Government is not the solution to our problems; Government is the problem.
CJ7-Tim is offline   Reply With Quote Quick reply to this message
Unread 06-12-2012, 03:58 AM   #3
noxj
Registered User
2001 XJ Cherokee 
 
Join Date: May 2012
Location: New Orleans, LA
Posts: 16
Quote:
Originally Posted by CJ7-Tim View Post
Exactly what CEL codes did you download ? When exactly, and under what conditions, is it mis-firing ? What brand and part number spark plugs did you install ?

If you smell fuel under the hood, you have a fuel leak.
I didn't save the receipt from autozone so I don't have the code. If it is still lit after I change temp gauge and fuel filter I will save receipt. The temp gauge was a little foul when I pulled it last night so I will see if that turns out to be my problem.

It is misfiring at idle, but I'm not convinced that is is consistent. I feel like it has the power that it should while accelerating, so I know that its not missing half the cylinders (1,3,5 were reported by the comp.)

As far as plugs they were autolite coppers. Nothing fancy as I know the 4.0 prefers cheap plugs. These were in the Napa computer system.

Ok will check on the fuel leak, thank you very much

-Noah
noxj is offline   Reply With Quote Quick reply to this message
Unread 06-12-2012, 09:48 AM   #4
CJ7-Tim
Real Jeeps have dents.
 
CJ7-Tim's Avatar
2000 XJ Cherokee 
 
Join Date: Apr 2002
Location: out in the garage - Minneapolis, Minnesota
Posts: 21,820
The Jeep in-line 6 cylinder has never been known for smooth idling. If it idles at 600-800 rpm's, and doesn't stall, it is fine. AutoLite copper plug should be OK. I prefer NGK or Champion copper or the AutoLite APP-985 for the 2000+ 4.0L.
__________________
.

Between 2009 when Obama took office, and 2013, median annual household incomes have fallen by more than $2,100.

Progressive Liberalism: Bringing you new Healthcare ideas so wonderful, they have to include mandatory participation ......

Originally Posted by Ronald W. Reagan: Government is not the solution to our problems; Government is the problem.
CJ7-Tim is offline   Reply With Quote Quick reply to this message
Unread 06-12-2012, 10:01 AM   #5
buildin1XJ
Web Wheeler
1999 XJ Cherokee 
 
Join Date: Oct 2011
Location: Knoxville, Tn.
Posts: 1,580
Just wondered if one of the codes pulled was a random cylinder misfire,or just the three you mention. If you smell fuel in the engine bay like Tim said you must have a leak. Maybe the fuel injectors o rings for just those three cylinders.
buildin1XJ is offline   Reply With Quote Quick reply to this message
Unread 06-12-2012, 04:36 PM   #6
noxj
Registered User
2001 XJ Cherokee 
 
Join Date: May 2012
Location: New Orleans, LA
Posts: 16
Quote:
Originally Posted by CJ7-Tim View Post
The Jeep in-line 6 cylinder has never been known for smooth idling. If it idles at 600-800 rpm's, and doesn't stall, it is fine. AutoLite copper plug should be OK. I prefer NGK or Champion copper or the AutoLite APP-985 for the 2000+ 4.0L.
Haha yeah true that. In that case it is idling just fine.
The individual codes were:
-P0301
-P0303
-P0305



Quote:
Originally Posted by buildin1XJ View Post
Just wondered if one of the codes pulled was a random cylinder misfire,or just the three you mention. If you smell fuel in the engine bay like Tim said you must have a leak. Maybe the fuel injectors o rings for just those three cylinders.
I think you're thinking along the right track. For each of the three codes, the readout was as follows:
--Definition
--Cylinder misfire detected - cylinder number 1,3,5 (for each individual code, stating for clarity)
--Explanation:
--the powertrain control module monitors the crankshaft speed and has detected a misfire condition
--Probable Cause:
--Ignition system fault - spark plugs, ignition wires, coil ****new everything so this is not answer unfortunately
--Vacuum Leak
--injector fault
--high or low fuel pressure

I'm still thinking the fuel smell and the misfires are related so I will check injectors. In fact, I know the fuel lines themselves aren't leaking and I was at a dead end there. Hopefully I can update with good news but if anyone has any ideas or experiences to share that would be great. Thank you both
-Noah

Last edited by noxj; 06-12-2012 at 04:37 PM.. Reason: Edited for clarity
noxj is offline   Reply With Quote Quick reply to this message
Unread 06-12-2012, 04:42 PM   #7
CJ7-Tim
Real Jeeps have dents.
 
CJ7-Tim's Avatar
2000 XJ Cherokee 
 
Join Date: Apr 2002
Location: out in the garage - Minneapolis, Minnesota
Posts: 21,820
Here are some generic Jeep misfire causes. I would add a bottle of fuel injector cleaner to the next 2-3 gas tank fill-ups.

Possible causes
- Faulty spark plug
- Faulty ignition coil
- Ignition coil harness is open or shorted
- Ignition coil poor electrical connection
- Clogged or faulty fuel injector
- Injector harness is open or shorted
- Injector poor electrical connection
- Improper spark plug
- Insufficient cylinder compression
- Incorrect fuel pressure
- Intake air leak
__________________
.

Between 2009 when Obama took office, and 2013, median annual household incomes have fallen by more than $2,100.

Progressive Liberalism: Bringing you new Healthcare ideas so wonderful, they have to include mandatory participation ......

Originally Posted by Ronald W. Reagan: Government is not the solution to our problems; Government is the problem.
CJ7-Tim is offline   Reply With Quote Quick reply to this message
Unread 06-12-2012, 04:49 PM   #8
noxj
Registered User
2001 XJ Cherokee 
 
Join Date: May 2012
Location: New Orleans, LA
Posts: 16
Quote:
Originally Posted by CJ7-Tim View Post
Here are some generic Jeep misfire causes. I would add a bottle of fuel injector cleaner to the next 2-3 gas tank fill-ups.

Possible causes
- Faulty spark plug
- Faulty ignition coil
- Ignition coil harness is open or shorted
- Ignition coil poor electrical connection
- Clogged or faulty fuel injector
- Injector harness is open or shorted
- Injector poor electrical connection
- Improper spark plug
- Insufficient cylinder compression
- Incorrect fuel pressure
- Intake air leak


Thanks Tim I will add these to the check list.
-Noah
noxj is offline   Reply With Quote Quick reply to this message
Unread 06-12-2012, 04:55 PM   #9
noxj
Registered User
2001 XJ Cherokee 
 
Join Date: May 2012
Location: New Orleans, LA
Posts: 16
Also how terrible is it that I'm dumping all this unburnt fuel into my cats? I'm forced to drive it 6 miles a day, I really don't have another option. I doubt it will be many more days before I hunt this thing down. Just wondering thank you
-Noah

Last edited by noxj; 06-12-2012 at 04:56 PM.. Reason: 1 more question added
noxj is offline   Reply With Quote Quick reply to this message
Unread 06-12-2012, 05:09 PM   #10
CJ7-Tim
Real Jeeps have dents.
 
CJ7-Tim's Avatar
2000 XJ Cherokee 
 
Join Date: Apr 2002
Location: out in the garage - Minneapolis, Minnesota
Posts: 21,820
If the fuel smell is under the hood you probably have a leak, if the fuel smell is at the exhaust pipe you probably have a drippy fuel injector. The amounts of fuel in either case is a few drops. The misfires are not constant so you might be 1/4 of 1% (0.025 %) less fuel efficient.
__________________
.

Between 2009 when Obama took office, and 2013, median annual household incomes have fallen by more than $2,100.

Progressive Liberalism: Bringing you new Healthcare ideas so wonderful, they have to include mandatory participation ......

Originally Posted by Ronald W. Reagan: Government is not the solution to our problems; Government is the problem.
CJ7-Tim is offline   Reply With Quote Quick reply to this message
Unread 06-12-2012, 10:05 PM   #11
theguywithjeeps
Registered User
1989 MJ Comanche 
 
Join Date: May 2012
Location: Lorain, Ohio
Posts: 40
go to the fuel pressure regulator at the front of the fuel rail and pull the vaccume line. if gas comes out the regulator then that is your problem. it was mine. also make sure your codes are cleared after you replace somthing
theguywithjeeps is offline   Reply With Quote Quick reply to this message
Unread 06-12-2012, 11:49 PM   #12
justanotherjpr
Registered User
 
Join Date: Nov 2007
Posts: 6,337
Its probably injector heat soak. Try hood vents, a e-fan switch and/or the heat wrap for your injectors. I had to use all three.
justanotherjpr is offline   Reply With Quote Quick reply to this message
Unread 06-13-2012, 08:39 AM   #13
CJ7-Tim
Real Jeeps have dents.
 
CJ7-Tim's Avatar
2000 XJ Cherokee 
 
Join Date: Apr 2002
Location: out in the garage - Minneapolis, Minnesota
Posts: 21,820
Quote:
Originally Posted by theguywithjeeps View Post
go to the fuel pressure regulator at the front of the fuel rail and pull the vaccume line.
Later OBD-II Cherokee do not have this.


At startup, the engine management is in open loop, and mis-fires due to heat soak, drippy injectors, or a faulty check valve don't trigger a CEL.
__________________
.

Between 2009 when Obama took office, and 2013, median annual household incomes have fallen by more than $2,100.

Progressive Liberalism: Bringing you new Healthcare ideas so wonderful, they have to include mandatory participation ......

Originally Posted by Ronald W. Reagan: Government is not the solution to our problems; Government is the problem.
CJ7-Tim is offline   Reply With Quote Quick reply to this message
Reply

Tags
fuel leak , ignition , spark plugs , temperature gauge

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the JeepForum.com forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid e-mail address for yourself.
Note: All free e-mails have been banned due to mis-use. (Yahoo, Gmail, Hotmail, etc.)
Don't have a non-free e-mail address? Click here for a solution: Manual Account Creation
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.


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.