4.0 5 speed sluggish - JeepForum.com
 2Likes
Reply
 
LinkBack Thread Tools
post #1 of 20 Old 08-10-2017, 09:39 PM Thread Starter
tropicalYJ
Registered User
1993 YJ Wrangler 
 
Join Date: Aug 2017
Location: Miami
Posts: 29
Garage
4.0 5 speed sluggish

My 93 YJ 4.0 5 speed is my DD. I can hardly get the darn thing to rev past 2k rpm in gear. In neutral, I can free rev to redline without an issue. I have the stock 3.07 gearing and I'm running 33s. The Jeep feels so sluggish compared to my TJ. I like to be able to open up the engine on an empty road, but I'm forced to shift at 2k.

Is a 4.56 re-gear something I should do? Or is there something else possibly going on?

tropicalYJ is offline  
Sponsored Links
Advertisement
 
post #2 of 20 Old 08-11-2017, 03:12 AM
Drednot
Registered User
1991 YJ Wrangler 
 
Join Date: Aug 2005
Location: Phoenix
Posts: 3,809
Quote:
Originally Posted by tropicalYJ View Post
Or is there something else possibly going on?
Does it rev normally in low range?

91 YJ Sahara, 4.0L, AX-15/NP231, D30/D35@3.07
12 Cherokee 4x4,3.7L,42RLE/MP1522, D30M/8.25@3.73
Emission test=YES
"Non Vi Sed, Arte"
Drednot is offline  
post #3 of 20 Old 08-11-2017, 06:06 AM
ionakana
Grand Poobah
 
ionakana's Avatar
1994 YJ Wrangler 
 
Join Date: Sep 2006
Location: Cumming GA
Posts: 4,909
Clogged Cat? Clogged fuel filter? I had a lack of power once, I was driving and felt it when it happened. Did the standard tune up, fuel filter and nothing helped. Checked compression, fuel pressure and everything was good. Took it to mechanics and they couldn't find anything wrong. After a year of trying to figure out I dropped the tank and replaced the original fuel pump out of desperation, after all, it was 21 years old. When I pulled it out the strainer was nasty, how I was reading good fuel pressure is beyond me. Put the new pump in and power was back. I'm 99% sure it was just the strainer and the pump was fine.

Psalm 14:1




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




Live in Georgia? click here-->
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
ionakana is offline  
 
post #4 of 20 Old 08-11-2017, 07:45 AM
mike134
Web Wheeler
1989 YJ Wrangler 
 
Join Date: Aug 2014
Location: Cleveland
Posts: 6,034
Check your codes by following the video link below. Is there any difference between warm engine vs cold engine?

Next use a multimeter to test your coolant temperature sensor. Compare the resistance to the air intake sensor. Do this when the engine is very cold and then again when it is warmed up.

ionakana makes a good suggestion too. But the fuel pump USUALLY progressively breaks down. Meaning it gets worse and worse until total failure. So if you've had your problem for a long time, I would leave the fuel pump and screen for last.

Plugged cat can do it too.

Your power should increase until a little over 3000, then it should level off as you increase RPM. It shouldn't fall though.

mike134 is offline  
post #5 of 20 Old 08-11-2017, 09:35 PM Thread Starter
tropicalYJ
Registered User
1993 YJ Wrangler 
 
Join Date: Aug 2017
Location: Miami
Posts: 29
Garage
[quote=mike134;38714369]Check your codes by following the video link below. Is there any difference between warm engine vs cold engine?

Next use a multimeter to test your coolant temperature sensor. Compare the resistance to the air intake sensor. Do this when the engine is very cold and then again when it is warmed up.

ionakana makes a good suggestion too. But the fuel pump USUALLY progressively breaks down. Meaning it gets worse and worse until total failure. So if you've had your problem for a long time, I would leave the fuel pump and screen for last.

Plugged cat can do it too.

Your power should increase until a little over 3000, then it should level off as you increase RPM. It shouldn't fall though.




Cold engine in gear sounds like a jet engine. Warm engine just feels bogged down with no power. When I apply a lot of gas pedal, I hear a whistle sound which I assume is the cold air intake I have on, but as the tach nears 2000 RPM, I also hear a whine. I tried to floor the gas today in 2nd gear and I managed to only get to 2500 before it sounded like the motor was going to blow up. I also notice that my gas pedal has a lot of vibration to it as I drive. Feels like it isn't going down smoothly as it should. I can't make it to 3000 RPM in gear, but I do know I gain no momentum after 2k.

Nobody mentioned my stock gearing and 33s, is that not a contributor to this sluggish acceleration? I will be changing out my entire exhaust system soon as I want something a little louder. Isn't rusty or anything though, and when I bang on the cat & muffler it doesn't rattle or sound like any loose junk may be inside.

I will be trying out your suggestion of the sensor this weekend. This Jeep has no pickup whatsoever. Takes me a solid 7 or 8 seconds to reach 40 mph, and that's if I'm pushing it. It only has 104k on the clock. No engine codes either.
tropicalYJ is offline  
post #6 of 20 Old 08-11-2017, 09:41 PM Thread Starter
tropicalYJ
Registered User
1993 YJ Wrangler 
 
Join Date: Aug 2017
Location: Miami
Posts: 29
Garage
Haven't tried, but I've read somewhere about 4lo and gearing. I'll try that this weekend
tropicalYJ is offline  
post #7 of 20 Old 08-11-2017, 10:22 PM
CooterWilly
Junior Member
 
CooterWilly's Avatar
 
Join Date: Jul 2017
Location: Athens
Posts: 22
Garage
Yeah, I'll be shopping for a new fuel pump myself since mine quit today. One minute it was working, the next minute I was sitting on the side of the road. Luckily I was close to home and the tow truck driver only charged me $45.
Anybody recommend a particular brand, or one to stay away from?
CooterWilly is offline  
post #8 of 20 Old 08-11-2017, 11:37 PM
Chrisnvegas
Web Wheeler
 
Chrisnvegas's Avatar
1992 YJ Wrangler 
 
Join Date: Dec 2012
Location: The Desert
Posts: 6,452
@CooterWilly Bosch is the fuel pump the factory used on my export model YJ.
It's a big strong pump which is still in service after 25 years.
The export model YJ was designed for poor quality fuels abroad.

@tropicalYJ
The stock air cleaner is a cold air intake. The cold air intake isn't.
It draws hot air from under the hood.
The stock airbox draws air in from behind the drivers side headlight.
If you have the stock air intake, put it back on. It flows plenty of air.
The restriction (minimal) is the tube to the throttle body, not the airbox.
"cold air" intakes are known to allow dirt into the engine.
It's all garbage marketing. If they worked, the factory would have put them on and picked up the 20 horsepower. They're not going to let an easy 20 horse sitting on the table.

Next:

I'm not sure a weak fuel pump is gonna make the engine sound like it's gonna blow up.
And 3:07's are going to let it rev freely to redline, 33's or not.
It may be less efficient on the freeway as the rpm will be under the target for the torque curve of the engine.

A plugged cat could cause the symptoms you are having.

Any way to post a video of the sound?

"Auto racing began 5 minutes after the second car was built."
Henry Ford
Chrisnvegas is offline  
post #9 of 20 Old 08-12-2017, 07:50 PM
CooterWilly
Junior Member
 
CooterWilly's Avatar
 
Join Date: Jul 2017
Location: Athens
Posts: 22
Garage
Thanks for the tip on the Bosch pump, Chris, but apparently Bosch is telling their suppliers that they don't have any in the warehouse.

Not trying to highjack the thread, but while we're waiting for an update from the OP I thought I'd share my fuel pump episode from today. While I was dropping the tank it started to rain, so I thought I'd run to the parts store and pick up a new one. The local store said "Yep, it's a direct replacement". When I got home and finally got the old one out, it was obviously different. By the way, it took about two and a half hours to get the filler and vent hoses disconnected because they had permanently molded into the shape of the plastic fitting. I didn't want to destroy them because replacement hoses are about a week away. So, when I called the local parts store, the guy said "Oh, you must have a twenty gallon tank, I gave you the one for the fifteen gallon tank. They have a twenty gallon tank pump at the store in the next town over." So I went to the other store, and the guy said "Yep, it's a direct replacement for a twenty gallon tank." You guessed it, not the right size. It simply would not fit the hanger, way too small. After Googling the only number on the old pump I found out the OTHER parts store had one on the shelf. When I went to get that pump I had the old one in hand and yep, it was an exact replica. When I got home with it, I mounted it exactly as the old one was mounted in the hanger. Good, time for reassembly, let's get this thing up and running. Well that's when I found out it wouldn't go back in the tank, the hanger assembly sat about an inch over the top of the tank. The bottom part of the assembly sits in a little plastic tray in the bottom of the tank, and after about an hour of finessing I finally got it back in. Geez. Okay, let me get the tank back in place. Well crap, if you line up the bolt holes in the back, the front ones don't line up. Another hour or so later I finally got the tank back in place. By this time it was 96 degrees outside and about 96% humidity. Ugh. Anyway, I thought I'd slip the filler and vent hose back on (I greased them up for easy replacement) but that's when I discovered there's a piece of sheet metal that prevents you from reattaching the filler hose if the tank is all the way up where it's supposed to be...

I guess I'll drop the tank again tomorrow and see what happens.
Chrisnvegas likes this.
CooterWilly is offline  
post #10 of 20 Old 08-12-2017, 10:28 PM
mike134
Web Wheeler
1989 YJ Wrangler 
 
Join Date: Aug 2014
Location: Cleveland
Posts: 6,034
CooterWilly,

You should definitely start your own thread because it's different than the OP, and I think people might be interested in following your repair as well.
mike134 is offline  
post #11 of 20 Old 08-13-2017, 10:32 PM Thread Starter
tropicalYJ
Registered User
1993 YJ Wrangler 
 
Join Date: Aug 2017
Location: Miami
Posts: 29
Garage
Quote:
Originally Posted by Chrisnvegas View Post
@CooterWilly Bosch is the fuel pump the factory used on my export model YJ.
It's a big strong pump which is still in service after 25 years.
The export model YJ was designed for poor quality fuels abroad.

@tropicalYJ
The stock air cleaner is a cold air intake. The cold air intake isn't.
It draws hot air from under the hood.
The stock airbox draws air in from behind the drivers side headlight.
If you have the stock air intake, put it back on. It flows plenty of air.
The restriction (minimal) is the tube to the throttle body, not the airbox.
"cold air" intakes are known to allow dirt into the engine.
It's all garbage marketing. If they worked, the factory would have put them on and picked up the 20 horsepower. They're not going to let an easy 20 horse sitting on the table.

Next:

I'm not sure a weak fuel pump is gonna make the engine sound like it's gonna blow up.
And 3:07's are going to let it rev freely to redline, 33's or not.
It may be less efficient on the freeway as the rpm will be under the target for the torque curve of the engine.

A plugged cat could cause the symptoms you are having.

Any way to post a video of the sound?



I'll upload a video to youtube and post the link tomorrow morning. Sorry for the delayed responses, been busy with work. You'll see in the video, but my symptom is that in gear the RPM likes to stay way below 2000. I'll also get a clip of what happens when I try to rev it up in a gear. Definitely not normal
Chrisnvegas likes this.
tropicalYJ is offline  
post #12 of 20 Old 08-14-2017, 04:15 AM
DirtKar
I pledge allegiance.
 
DirtKar's Avatar
1993 YJ Wrangler 
 
Join Date: Jun 2012
Location: Nor Cal Sierras
Posts: 3,848
"Cold engine in gear sounds like a jet engine. Warm engine just feels bogged down with no power."

"This Jeep has no pickup whatsoever. ."


Please clarify. If you take off immediately on a cold engine does it rev normally?

Quote:
Originally Posted by Anticanman

Come on by! It's easy to network locally when you join a 4x4 club especially when all the clubs in your state are united and invited to each other's runs. You meet poor folk like me or run into guys that own some of the big companies you only aspire to order from and drool when you see their products. The great uniting factor is that we are all jeepers at heart and are willing to help each other out even if its just a little. That's what the jeep wave is all about: community. The wave is the tip of the iceberg.
__________________
Luck Favours The Prepared
YJOTM JULY 2014
DirtKar is offline  
post #13 of 20 Old 08-14-2017, 09:51 AM Thread Starter
tropicalYJ
Registered User
1993 YJ Wrangler 
 
Join Date: Aug 2017
Location: Miami
Posts: 29
Garage
Quote:
Originally Posted by Chrisnvegas View Post
@CooterWilly Bosch is the fuel pump the factory used on my export model YJ.
It's a big strong pump which is still in service after 25 years.
The export model YJ was designed for poor quality fuels abroad.

@tropicalYJ
The stock air cleaner is a cold air intake. The cold air intake isn't.
It draws hot air from under the hood.
The stock airbox draws air in from behind the drivers side headlight.
If you have the stock air intake, put it back on. It flows plenty of air.
The restriction (minimal) is the tube to the throttle body, not the airbox.
"cold air" intakes are known to allow dirt into the engine.
It's all garbage marketing. If they worked, the factory would have put them on and picked up the 20 horsepower. They're not going to let an easy 20 horse sitting on the table.

Next:

I'm not sure a weak fuel pump is gonna make the engine sound like it's gonna blow up.
And 3:07's are going to let it rev freely to redline, 33's or not.
It may be less efficient on the freeway as the rpm will be under the target for the torque curve of the engine.

A plugged cat could cause the symptoms you are having.

Any way to post a video of the sound?
Won't let me post links since I'm new to the Forum but on YouTube, search "Jeep YJ 4.0 rough".

Sorry, the video is not the best quality but I was using my phone. If you listen carefully you can hear the high pitched whistle and a little whine, more towards the end of the video. The first part is me driving how I normally drive. The 2nd part is me pushing it. I was literally flooring the gas pedal. For some reason the video makes it sound ok, but in person the engine sounded like it was at 4500 RPM, not 3000. No power either, while it did rev high by flooring, the Jeep did not accelerate much after 2500 which is why I shifted. In person, the whistle sounds like intake but then there is a whine that sounds like something to do with the axles or driveshafts. Unfortunately the video makes my symptoms look mild. This is one of those things where you need to feel it/drive it to fully understand it.

Sorry for the noob questions but I'm still learning a lot about cars and Jeeps, is there a possibility that maybe the tachometer is not reading correctly? I've had problems before with it randomly going to 0 and it sometimes bounces a little at idle. I feel like I'm at a higher RPM than the tach is reading.
tropicalYJ is offline  
post #14 of 20 Old 08-14-2017, 11:00 AM
Chrisnvegas
Web Wheeler
 
Chrisnvegas's Avatar
1992 YJ Wrangler 
 
Join Date: Dec 2012
Location: The Desert
Posts: 6,452

"Auto racing began 5 minutes after the second car was built."
Henry Ford
Chrisnvegas is offline  
post #15 of 20 Old 08-14-2017, 04:10 PM
mike134
Web Wheeler
1989 YJ Wrangler 
 
Join Date: Aug 2014
Location: Cleveland
Posts: 6,034
Hmmm. I must be missing something. I don't see the problem in that video. It seems like you are routinely shifting around 3,000 RPM. Tachometer is going from 2000 to 3000 fairly quickly.
mike134 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









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