Check Engine Code po300 - JeepForum.com
 
LinkBack Thread Tools
post #1 of 5 Old 09-15-2013, 05:23 PM Thread Starter
JeepgrlFl
Registered User
1997 ZJ 
 
Join Date: Sep 2013
Location: Ormond Beach
Posts: 1
Check Engine Code po300

I keep getting a po300, 302, 303, 304, and 305 check engine light reading. I put in a fuel injector cleaner a month ago. I'm at a loss of what to do. My mechanic is no help and wants to charge me an arm and a leg to do bunch of things I didnt really understand. Any suggestions???

JeepgrlFl is offline  
Sponsored Links
Advertisement
 
post #2 of 5 Old 09-15-2013, 05:33 PM
Oldfrog
Registered User
2007 WK 
 
Join Date: Feb 2008
Location: Louisiana/Texas
Posts: 5,091
Please complete your profile about your Jeep.
Which engine? What year model?...etc.

Ok...haha...I see you were doing that as I was typing.

2007 5.7 Hemi, Ltd. QD II -
1997 ZJ, 4,0 select trac, Up country, track lok.
Oldfrog is offline  
post #3 of 5 Old 09-15-2013, 05:38 PM
Oldfrog
Registered User
2007 WK 
 
Join Date: Feb 2008
Location: Louisiana/Texas
Posts: 5,091
Multiple misfires.
Symptoms?

2007 5.7 Hemi, Ltd. QD II -
1997 ZJ, 4,0 select trac, Up country, track lok.
Oldfrog is offline  
post #4 of 5 Old 09-16-2013, 06:38 AM
newfieZJ
Registered User
1995 ZJ 
 
Join Date: May 2008
Posts: 6,557
Typically , a tune up will cure this issue . Plugs , wires , cap and rotor .

Occasionally , a weak coil can do it . Bad grounds might make the coil signal weak also . Check and clean connections

Fuel pressure should be tested with a gauge , and can cause the issue if not right

Bad or poor signal from the crank position sensor (CPS)

Check wires around exhaust for any shorts

Lastly , valve springs . 97-98 apparently saw a batch of weak springs . Jeep has a TSB to address that problem which is nothing more than replacing the valve springs and cleaning the carbon that typically builds up from this problem out the combustion chambers causing the mis-fires .

Attempt a good misting with a water hose while the engine is running . See if it starts running rough . Good ignition systems can handle a little water with no effect .

Disconnect the battery , clear the codes . Give 30 mins disconnected to be certain it's cleared . As soon as the jeep tosses a check engine light , check the codes ASAP , report results here .
newfieZJ is offline  
post #5 of 5 Old 09-16-2013, 07:30 AM
johns1mj
Registered User
1995 ZJ 
 
Join Date: Aug 2013
Location: midland
Posts: 170
When you change your cap and rotor check the distributor shaft for movement. I have seen a couple of these "wobble" from the bushings going bad.
johns1mj is offline  
Reply

Tags
check engine light

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.



Email Address:
OR

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.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Posting Rules  
You may post new threads
You may 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 On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome