Losing my mind! Rough running TJ - JeepForum.com
 2Likes
Reply
 
LinkBack Thread Tools
post #1 of 17 Old 07-10-2020, 11:36 AM Thread Starter
Searkjeep88!
Registered User
 
Join Date: Jul 2020
Posts: 9
Losing my mind! Rough running TJ

New guy, first post. 98 TJ 4.0 5 speed man. I've all over the web and keep going in circles. Just bought this rig and knew about the rough running problem but got a good deal and figured I could easily fix it. Funny thing is when I first turn it over it starts right up and runs great. Handful of seconds later it starts to slightly miss. When accelerated it misses and backfires out of intake and exhaust. Previous owner replaced distributor, wires, plugs, injectors, sensors on manifold, new computer and I keep finding recently replaced parts along the way. Replaced O2 sensor but I could only find one!? Seems like such a simple fix but very aggregated.

Searkjeep88! is offline  
Sponsored Links
Advertisement
 
post #2 of 17 Old 07-10-2020, 12:03 PM
RedBolide
Registered User
 
Join Date: Dec 2019
Location: Atlanta
Posts: 54
Put simply, your Jeep needs the right amount of fuel, air, and spark to run. One of those isn't functioning properly. Sounds like the previous owner dealt with most things that could pertain to spark. Still worthwhile to double check. You might want to make sure that there's no glaring vacuum leaks. It would have to be pretty bad to cause the issues you described. My bet is it's an issue with fuel delivery. Are your injectors working properly? Is your fuel pump making the right pressure? If fuel, air, and spark all look good, then there's a chance it's a sensor problem, but I'd check on all the other stuff first.

'03 Wrangler Sport / '98 Grand Cherokee Laredo / '90 Comanche Eliminator
RedBolide is offline  
post #3 of 17 Old 07-10-2020, 01:01 PM Thread Starter
Searkjeep88!
Registered User
 
Join Date: Jul 2020
Posts: 9
Injectors are new but I know that means nothing. Pressure was staying consistent around 39-40 something. I checked spark and seemed slightly weak to me maybe cmp? Working on that now. This is my first fuel injection (gosh that carb was easy)
Searkjeep88! is offline  
 
post #4 of 17 Old 07-10-2020, 03:21 PM
jtec
Web Wheeler
 
jtec's Avatar
2014 JK Wrangler 
 
Join Date: Oct 2017
Posts: 8,425
Start with a SCAN for codes, this jeep is new to you SO lets start there.

Tell us do you have a scanner able to see live data?

When I see the price of OEM I think aftermarket.
When I see the quality of aftermarket I think OEM.
jtec is offline  
post #5 of 17 Old 07-10-2020, 04:54 PM Thread Starter
Searkjeep88!
Registered User
 
Join Date: Jul 2020
Posts: 9
No I don't but am willing to. I have one that simply reads the codes and allows you to delete. What one do you recommend? The main code is a camshaft sensor (which I don't have) and crankshaft sensor that I'm waiting to arrive in the morning. The wires seemed to have gotten close to exhaust and melted, may have been the culprit.
Searkjeep88! is offline  
post #6 of 17 Old 07-10-2020, 04:56 PM
TJ4Jim
Registered User
1999 TJ Wrangler 
 
Join Date: Nov 2013
Location: Brookings
Posts: 820
Take a look at the ignition coil, you have the pre-coil rail system and the coils have a tendency to corrode internally and split open, a weak spark as she warms up can cause issues.

If you come to a fork in the road take it.
TJ4Jim is offline  
post #7 of 17 Old 07-10-2020, 05:00 PM
mukluk
Web Wheeler
 
mukluk's Avatar
2000 TJ Wrangler 
 
Join Date: Oct 2010
Location: Clyde
Posts: 6,094
Quote:
Originally Posted by Searkjeep88! View Post
The main code is a camshaft sensor (which I don't have) and crankshaft sensor that I'm waiting to arrive in the morning. The wires seemed to have gotten close to exhaust and melted, may have been the culprit.
You most certainly do have a camshaft sensor, it's located inside the distributor. It often helps to post up the specific codes you're getting when you know what they are.
Attached Images
 

2000 TJ SE
2005 LJ Rubicon
mukluk is offline  
post #8 of 17 Old 07-10-2020, 06:01 PM
BlueFl.Wrangler
Supporting Member
 
BlueFl.Wrangler's Avatar
2002 TJ Wrangler 
 
Join Date: Aug 2019
Location: Inglis,Fl.
Posts: 345
That backfiring sounds like a timing issue to me- The PO messing with the dist. sounds like a good place to start

Diplomacy is the art of telling people to go to hell in such a way that they ask for directions

Winston Churchill
BlueFl.Wrangler is offline  
post #9 of 17 Old 07-10-2020, 06:21 PM
TJ4Jim
Registered User
1999 TJ Wrangler 
 
Join Date: Nov 2013
Location: Brookings
Posts: 820
Quote:
Originally Posted by BlueFl.Wrangler View Post
That backfiring sounds like a timing issue to me- The PO messing with the dist. sounds like a good place to start
Good point.

Maybe just put her on TDC to see where the rotor lines up.

If you come to a fork in the road take it.
TJ4Jim is offline  
post #10 of 17 Old 07-10-2020, 07:27 PM Thread Starter
Searkjeep88!
Registered User
 
Join Date: Jul 2020
Posts: 9
That distributor sensor is different from the camshaft sensor from what I understand. Like I said earlier the code is camshaft sensor AND crankshaft sensor needs replacing but I don't have a camshaft sensor. It's a distributor sensor.
Searkjeep88! is offline  
post #11 of 17 Old 07-10-2020, 07:52 PM
mukluk
Web Wheeler
 
mukluk's Avatar
2000 TJ Wrangler 
 
Join Date: Oct 2010
Location: Clyde
Posts: 6,094
Quote:
Originally Posted by Searkjeep88! View Post
That distributor sensor is different from the camshaft sensor from what I understand. Like I said earlier the code is camshaft sensor AND crankshaft sensor needs replacing but I don't have a camshaft sensor. It's a distributor sensor.
Name:  Cam Sensor.jpg
Views: 13
Size:  163.4 KB

Post up the Pxxxx code. No trouble code tells you that a specific part needs to be replaced, it only tells you there is a fault within a circuit or with a signal. That's not to say the component within that circuit isn't bad, but it definitely isn't the only possible cause for the fault code.
NashvilleTJ and jtec like this.

2000 TJ SE
2005 LJ Rubicon
mukluk is offline  
post #12 of 17 Old 07-11-2020, 02:09 AM
Jonny Jeep
Web Wheeler
 
Jonny Jeep's Avatar
1997 TJ Wrangler 
 
Join Date: Feb 2007
Location: Manchester
Posts: 6,509
39-40 psi is too low. It should be 49.2psi or just either side of that. What brand O2 sensor did you use for replacement? NTK was OEM supplier and recommended. You should have two sensors, upstream just below where the manifold bolt to the exhaust, and downstream after the cat near the rear of the transfer case. Might be worth unplugging the upstream O2 and seeing how it runs without it.


From fairly low speed how's the acceleration through the rev range if you accelerate hard through the gears? I used to seem low on power through the midrange and have an occasional hesitation on going WOT before my pump failed. I used to get some popping when coming off throttle too.


The CaMshaft Position (CMP) sensor is known by many names in the after market including distributor or ignition sensor.
Jonny Jeep is online now  
post #13 of 17 Old 07-11-2020, 06:50 AM
jtec
Web Wheeler
 
jtec's Avatar
2014 JK Wrangler 
 
Join Date: Oct 2017
Posts: 8,425
Searkjeep88! how is the repair going? Whats a new?

When I see the price of OEM I think aftermarket.
When I see the quality of aftermarket I think OEM.
jtec is offline  
post #14 of 17 Old 07-11-2020, 08:00 AM Thread Starter
Searkjeep88!
Registered User
 
Join Date: Jul 2020
Posts: 9
Headed to pick up crankshaft sensor as we speak and while I'm there will pick up camshaft sensor but they will more than likely have to order. Will check fuel pressure again when I get it back going. TDC everything is lined up as it should be.
Searkjeep88! is offline  
post #15 of 17 Old 07-11-2020, 09:40 AM Thread Starter
Searkjeep88!
Registered User
 
Join Date: Jul 2020
Posts: 9
So installed new ckp, cleared code, motor turns over and stops. Now I have nothing. Won't even try to turn over. No codes.
Searkjeep88! is offline  
Reply

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











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