YJ 95 Good when cold, Bad when hot. - JeepForum.com
 1Likes
  • 1 Post By Boojo35
 
LinkBack Thread Tools
post #1 of 8 Old 02-17-2020, 07:38 AM Thread Starter
YJ_ZA
Registered User
 
Join Date: Jan 2019
Posts: 3
YJ 95 Good when cold, Bad when hot.

I need some pointers, to get my YJ to run normal when at operational level.
Jeep YJ 1995 i6

Problem:

Whenever I need power when she is at operation level (Dead center on heat gage), she start to bog badly, and it deteriorate from there. For example, it will initially only be a bog at almost wide open throttle, but then in minutes, the engine will stall when you step on the gas. But then switching off the ignition and immediately turning her back on will reset the issue, until you try to much gas. Starting when hot is easy, no issues there. Idling is fine. However, when she bogs, idling seems to be irregular for seconds intervals. Meaning that when I gear down or up, refs will continue for a few seconds and then drop back down.

I can drive her at operation temperature in town, no problem. But as soon as you try to overtake, and need to give gas(going up a steep hill), then it starts this sequence of bogging up to the point where she wants to stall when you step on the gas. This is a huge issue when going to 4x4 tracks.

What have I tried so far:
- I have redone the vacuum hose system to ensure no vacuum leak
- I have tested the Throttle position sensor, and found a reading of 0.8 to 3.9 at wide open throttle. No obvious dead spots
- Disconnected the O2 sensor on the manifold. Read that this could confuse the brainbox when the sensor is bad.
- Tested the fuel pump at the dealership. Report showed that it was still well in spec.


My hope is that somebody experienced this before, and can provide some pointers/ advise. I just feel that the fact that the ignition somehow influence the problem, may point to an electrical issue somewhere, as apposed to a cracked leaking manifold which would continuously cause bogging when hot. I would appreciate any guidance with this issue, thanks!
Attached is my beloved yet temperamental YJ bostokolos.

Attached Images
 
YJ_ZA is offline  
Sponsored Links
Advertisement
 
post #2 of 8 Old 02-17-2020, 11:25 AM
fishadventure
Web Wheeler
 
fishadventure's Avatar
1989 YJ Wrangler 
 
Join Date: Jul 2013
Location: Morrisville
Posts: 7,264
Garage
Well the symptom shows any number of things.

The first thing to mind is air getting into the exhaust stream and lying to the O2 sensor. Which should stay plugged in btw.
A cracked exhaust manifold is a common item for this.

Is this an automatic?

I still wonder about vacuum leaks (intake/exhaust manifold gasket) too.

Did you read the codes?

Is your cat plugged?

[size=3]Shackles & D-rings are different things.
Cranking IS turning over
fishadventure is offline  
post #3 of 8 Old 02-17-2020, 11:55 AM
TSEJEEPERS
Registered User
 
TSEJEEPERS's Avatar
1993 YJ Wrangler 
 
Join Date: Dec 2003
Location: Morton IL
Posts: 6,215
Did you do anything to your Jeep before this started? Tune up, fuel filter ect.

93 YJ SOA 2" springs front, XJ springs rear w/main leaf added, High pinon 9 inch rear detroit locker front Dana 44 ARB 4.56 Gears, 36 inch Irok tires too much to list.
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
TSEJEEPERS is offline  
 
post #4 of 8 Old 02-17-2020, 11:55 AM
Waternut
Web Wheeler
 
Waternut's Avatar
1988 YJ Wrangler 
 
Join Date: Sep 2016
Location: Macon
Posts: 1,212
The fact that you can shut it down, restart it, and have the problem go away when already warm makes think that this is not a O2 or exhaust issue. Kind of makes me think it's a fuel issue or something is clogged in the fuel rail, fuel injectors, or even a clogged fuel filter. Fuel pressure may be adequate which is what you would typically check but fuel flow may be the problem and that's not so easy to diagnose.

I think you should buy or rent a fuel pressure tester. They aren't expensive and your local auto parts store will likely rent you one for free. Your pump may be supplying enough pressure and flow at idle and quick blips of the throttle up to 2000rpms which you would generally do to verify functionality. However, a crack in the hose or leak in the fuel system (likely inside the tank) can really cause a host of issues that seem to be super weird. If you can somehow watch the fuel pressure gauge while you're driving, it would really help you troubleshoot. Maybe even pull the hood off real quick and go full redneck style down the road while you gas it hard and watch the gauge. I say this because 3k rpms at idle and 3k rpms under load have grossly different fuel requirements.

I did have a similar issue that turned out to be fuel pump/filter related except mine would start after 45 minutes of driving and I'd have to wait an hour before I could drive again once it sputtered out. I think my issue was that the pump was dying and once it started getting hot, it couldn't supply enough fuel. Changed the pump and filter and it cleaned up but then started again a week later. The second problem was caused by the hose blowing off the fuel pump inside the tank (my fault). The hose was sitting on the pump just enough to let the engine function properly up to about 1300 rpms but beyond that, it would bog and/or die.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.



To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Waternut is offline  
post #5 of 8 Old 02-17-2020, 02:03 PM
Boojo35
Registered User
1987 YJ Wrangler 
 
Join Date: Jul 2007
Location: Beer City
Posts: 2,042
Garage
I think it could be a clogged cat or should I say a cat that has broken apart inside and the chunks are possibly clogging the outlet or another part of the exhaust down stream under high exhaust flow. When it is shut off they fall back down or back out of place. A quick easy check is to smack the exhaust a listen for a rattle. Another easy check is to create an exhaust leak upstream from the cat and go for a quick spin.

This condition with cats is not terribly common but can be tricky to diagnose.
Siva283 likes this.

If you cannot fix it with a hammer then it has to be an electrical problem.
Boojo35 is offline  
post #6 of 8 Old 02-18-2020, 01:11 AM Thread Starter
YJ_ZA
Registered User
 
Join Date: Jan 2019
Posts: 3
Thanks for the responds.

@fishadventure , Its is a manual 5 speed. The bogging issue do not through an error. It only provide a 55 code. The cat was replaced mid last year. It was leaking due to some holes. The new exhaust only got a muffler.

I have bought this jeep about 2 years back, and only use it as a week end fun car. So she do not get out that much, and when she do, not always a trip in which this symptoms surface.

@TSEJEEPERS , I have only replaced TP sensor in the first 2 months when I bought her, and then the exhaust system(from the cat converter to the back of the jeep), and the vacuum pipes. As mentioned above, I only experience these symptoms when out on a proper ride (long distance or 4x4 track).

@Waternut , It sounds like a good Idea, I will get a fuel pressure meter and see if I can detect any starvation / variance in pressure when the symptoms do appear. Would I be able to see the advisable pressure numbers for the fuel pump in the maintenance manual? To see what it must be vs actual reading.

@ Boojo35, sounds logical, but I chucked the cat and replaced with a new system, which include only one muffler and no cats.

I guess way forward is to ensure the fuel pressure is stable and in spec when the symptoms appear, and having a check at the fuel filter. Will keep you posted.
YJ_ZA is offline  
post #7 of 8 Old 02-18-2020, 05:33 AM
Siva283
Registered User
 
Siva283's Avatar
1993 YJ Wrangler 
 
Join Date: May 2011
Location: Baltimore
Posts: 4,773
Quote:
Originally Posted by Boojo35 View Post
I think it could be a clogged cat or should I say a cat that has broken apart inside and the chunks are possibly clogging the outlet or another part of the exhaust down stream under high exhaust flow. When it is shut off they fall back down or back out of place. A quick easy check is to smack the exhaust a listen for a rattle. Another easy check is to create an exhaust leak upstream from the cat and go for a quick spin.

This condition with cats is not terribly common but can be tricky to diagnose.
This my jeep did this same type of thing a month ago from that CAT clogging. I would get it fixed before driving it to much. It really took its toll on my motor. I just swapped a new drivetrain in this weekend and the power difference is night and day. I even had goof compression numbers on the old engine. I think it caused some burnt valve I havent done exploratory surgery yet. It also made the head gasket blow and exhaust goes to the coolant.

You have 2 easy options to check for a plugged cat. Take the O2 sensore out or disconnect the exhaust at the manifold. See you you can make it do it. If you cant you need a new CAT.

From Amazon I put an entire new exhaust together with the TJ down pipe for $300. Then I used those fancy clamps to put it in.

1995 YJ. 2 inch BDS Spring lift. 1 inch shackle lift. 1.25 inch JKS Body Lift 33x12.5x15's. Engo 10,000 pound winch.

Quote:
Originally Posted by Magnum View Post
I gave the Jeep the required offering of $$, sweat, and blood, and everything works fine now. -- Jim
Quote:
Originally Posted by ldso View Post
. It started with a $200 axle, and a few thousand dollars later I was done :)
Quote:
Originally Posted by Luuca View Post
diagnose the real issue before you start going all Obama on it - spending mad cash you'll need for other important things.

Ask me how I know...
Quote:
Originally Posted by Overhead View Post
this is also my second set of RC springs this year. I'd rather spend the money again and get something that will last.
Siva283 is offline  
post #8 of 8 Old 02-18-2020, 05:52 AM
Waternut
Web Wheeler
 
Waternut's Avatar
1988 YJ Wrangler 
 
Join Date: Sep 2016
Location: Macon
Posts: 1,212
Quote:
Originally Posted by YJ_ZA View Post
@Waternut , It sounds like a good Idea, I will get a fuel pressure meter and see if I can detect any starvation / variance in pressure when the symptoms do appear. Would I be able to see the advisable pressure numbers for the fuel pump in the maintenance manual? To see what it must be vs actual reading.
I want to say the manuals are pretty vague but they do give the pressures. Double check my numbers but I think around 32psi is normal but you'll also want to disconnect the vacuum line on the fuel pressure regulator (small cylinder at the front of the fuel rail). With that vacuum line disconnected you should be seeing 40psi or more. If that checks out, try to pinch the return line for a split second and see if the fuel pressure spikes to around 70-80psi. I haven't done the pinch test myself but seen a lot of people say to try it.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.



To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Waternut 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