p0300 p0303 and p0304
#1
Newbie
Thread Starter
Join Date: Nov 2018
Posts: 6
Likes: 0
Received 0 Likes
on
0 Posts
Model: Cherokee (XJ)
p0300 p0303 and p0304
Hello, I'm new to the forum and new to jeeps. Was looking to purchase a really nice 2000 xj, the owner has been very honest with me and i'm just looking for answers to a disclosed problem with the jeep. The problem with the jeep is that the CEL comes on and throws codes P0300(misfire)P0303( cylinder 3 misfire) and P0304 (cylinder 4 misfire). it does not shut off but gets sluggish. this could happen when pulling out of driveway or after 40 miles, there is no real pattern. Sometimes shutting it off and clearing the codes fixes it, sometimes not. Seems like the computer is shutting down injectors 3 & 4.there has been compression tests done,heat soak, and also synchronizing the cam sensor, all were fine. since this started happening he has replaced the following-crank sensor, cam sensor, coil packs, plugs, fuel injectors, injection rail, flex plate, ecm, and engine wiring harness. he is thinking that the problem is electrical because of it having no pattern. he is just out of patients and is done throwing money at it! im just trying to find out what it might possibly be that he hasn't! already done, so i can be the jeep and enjoy it! Thanks in advance for any suggestions
Last edited by mkenz711; 11-27-2018 at 02:21 PM.
#2
Old fart with a wrench
Easy one for me. Look at the feed harness for the coil pack. There's probably a chaffed wire for coil #2.
Last edited by dave1123; 11-27-2018 at 07:27 PM.
#3
Newbie
Thread Starter
Join Date: Nov 2018
Posts: 6
Likes: 0
Received 0 Likes
on
0 Posts
Model: Cherokee (XJ)
Really?? That’s all you think it would be is an uninsulated wire? I sure hope that’s all it is, I would really like to purchase this Jeep but don’t want to start off frustrated with this issue, as the current owner is. What exactly is the feed harness? Is it worth replacing the entire harness? Thanks
#5
Old fart with a wrench
Really?? That’s all you think it would be is an uninsulated wire? I sure hope that’s all it is, I would really like to purchase this Jeep but don’t want to start off frustrated with this issue, as the current owner is. What exactly is the feed harness? Is it worth replacing the entire harness? Thanks
The bottom line is he honestly tried to fix it, but it's going to take an electrician to find the problem. As long as the compression is good I'm pretty sure there's nothing major wrong with it. The fuel injectors are powered up all the time the engine is running and the PCM GROUNDS them in sequence only when fuel is needed for that cylinder. It's hard for me to believe just 3 and 4 are effected.
Last edited by dave1123; 11-27-2018 at 08:45 PM.
#6
Senior Member
Without even attempting to dive into the problem as tired as I am I will say this . After being a career mechanic for many years now I will give you advice . Even if the person telling you about the issue is the best mechanic you know assume you know nothing . Assume any part new or old can be bad and that you need to start from scratch . I couldn’t tell you how many times misinformation has lead me down the wrong path , or how many times ignoring a new part for the simple fact that it is new has lead me into a spell .
#7
CF Veteran
Join Date: Nov 2017
Location: Groton, MA
Posts: 3,695
Received 234 Likes
on
207 Posts
Year: 1995
Model: Cherokee(XJ)
Engine: I6 4.0L
Wow - talk about "firing the parts cannon"!!!
I have to agree with GreaseMonkey. I'm not a professional mechanic, but merely working the parts counter at the local parts retailer for a couple years in college I've seen plenty of that.
The best way to know for sure is to see documentation - receipts for parts and service.
I also think Dave is onto something and my gut feeling is that the seller is a well intention-ed guy.
If it were me, I'd see if I could take the Jeep for some amount of time with freedom to dig into it and at least see if it is just a chafed wire. Maybe see if you can dig into it at his location for a few hours if nothing else.
IIRC that coil pack wiring is kind of a pain in the rear to get at.
I have to agree with GreaseMonkey. I'm not a professional mechanic, but merely working the parts counter at the local parts retailer for a couple years in college I've seen plenty of that.
The best way to know for sure is to see documentation - receipts for parts and service.
I also think Dave is onto something and my gut feeling is that the seller is a well intention-ed guy.
If it were me, I'd see if I could take the Jeep for some amount of time with freedom to dig into it and at least see if it is just a chafed wire. Maybe see if you can dig into it at his location for a few hours if nothing else.
IIRC that coil pack wiring is kind of a pain in the rear to get at.
Trending Topics
#8
Newbie
Thread Starter
Join Date: Nov 2018
Posts: 6
Likes: 0
Received 0 Likes
on
0 Posts
Model: Cherokee (XJ)
Thanks for all the advice. I’m really not sure what I want to do now. I know he has put a lot of time and money into it, with no avail, I’m just not sure that I want the same headaches.
#9
CF Veteran
Join Date: Nov 2017
Location: Groton, MA
Posts: 3,695
Received 234 Likes
on
207 Posts
Year: 1995
Model: Cherokee(XJ)
Engine: I6 4.0L
You might check around for a local automotive electrical expert or Jeep specialty shop that is willing to go through the wiring and find and replace anything that's not in good shape.
The other thing to be aware of with a 00 is the 0331 head defect - do some research on this if you're unaware. It's not related to the issues with the codes, but if you own a 00 Jeep you need to be aware of it.
#11
CF Veteran
Join Date: Nov 2017
Location: Groton, MA
Posts: 3,695
Received 234 Likes
on
207 Posts
Year: 1995
Model: Cherokee(XJ)
Engine: I6 4.0L
Anytime brother!
If you do decide to get the Jeep, this forum has a ton of awesome folks that regularly visit and have a ton of great advice. Dave, as you can see is super knowledgeable, there's a guy Jordan96xj who is really great with electrical stuff and Cruiser54 who was a head Jeep mechanic. Plus a ton of pro mechanics and Jeep experts.
I had a Toyota question and dealing with the Toyota forums made me greatful for this one - I had one answer to my question. Here you'll get multiple responses and folks willing to walk you through a diagnosis. Aside from having a Jeep mechanic at your side, you won't find better help.
If you do decide to get the Jeep, this forum has a ton of awesome folks that regularly visit and have a ton of great advice. Dave, as you can see is super knowledgeable, there's a guy Jordan96xj who is really great with electrical stuff and Cruiser54 who was a head Jeep mechanic. Plus a ton of pro mechanics and Jeep experts.
I had a Toyota question and dealing with the Toyota forums made me greatful for this one - I had one answer to my question. Here you'll get multiple responses and folks willing to walk you through a diagnosis. Aside from having a Jeep mechanic at your side, you won't find better help.
Thread
Thread Starter
Forum
Replies
Last Post
DudeManBro
Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go here
2
10-01-2018 11:37 PM
XJnine
Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go here
3
02-05-2014 02:48 PM
mntn-biker
Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go here
6
05-28-2013 09:20 AM
bbrasee
Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go here
2
10-12-2012 01:38 PM
Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)