• Welcome Visitor! Please take a few seconds and Register for our forum. Even if you don't want to post, you can still 'Like' and react to posts.

Bad MPG. Is cat clogged?


ford4wd08

Well-Known Member
Supporting Member
Joined
Nov 12, 2018
Messages
1,249
Reaction score
510
Points
113
Location
Alcoa, TN
Engine Type
2.8 V6
Transmission
Automatic
2WD / 4WD
4WD
What should be temperature outside cat? Will be check tomorrow
That I can't answer off the top of my head, but usually if they clog bad enough, they will glow hot.
 


Pauls14

Member
Joined
Jan 14, 2021
Messages
32
Reaction score
0
Points
6
Location
IL
Vehicle Year
1998
Make / Model
Ford Ranger
Engine Type
4.0 V6
Transmission
Automatic
2WD / 4WD
4WD
That I can't answer off the top of my head, but usually if they clog bad enough, they will glow hot.
Ok, thanks. Will write when check
 

ericbphoto

Overlander in development
TRS Event Staff
TRS Forum Moderator
Supporting Member
U.S. Military - Veteran
TRS 20th Anniversary
VAGABOND
TRS Event Participant
GMRS Radio License
Joined
Feb 7, 2016
Messages
15,200
Reaction score
16,335
Points
113
Age
59
Location
Wellford, SC
Vehicle Year
1993
Make / Model
Ford Ranger
Engine Type
3.0 V6
Engine Size
3.0L
Transmission
Manual
2WD / 4WD
4WD
Total Lift
6"
Tire Size
35"
My credo
In theory, theory and practice are the same. In practice, they are different.
Even healthy, they get too hot to touch.
 

gaz

Well-Known Member
U.S. Military - Veteran
Joined
Sep 21, 2007
Messages
1,380
Reaction score
621
Points
113
Location
Wa, Bremerton 98310
Vehicle Year
1987
Make / Model
Ford
Engine Size
87Ranger Endrigo 2.9l, 87BII Endrigo 4.0l
2WD / 4WD
4WD
Total Lift
Ranger 5" (2" suspension), BII 4" suspension
Total Drop
Ranger 5sp, BII A4LD
Tire Size
Ranger 33"/4:10LS, BII 29"/3:73LS
My credo
Deengineer until it is how Blue Oval should have sold it!!
Pauls14,

If you have verified the "alleged" tune up to be actual, here's what I would do:

1) complete the tune up with new engine oil, transmission and axle fluids, engine coolant flush/fill and verify your tire pressure.

If mileage is still crap,

2) have your valves checked and subsequent valve job performed by a competent, trusted machinist.

If mileage is still crap,

3) look at your valve train components. The rockers and push rod wear are known issues on these power plants. Also, you may want to consider the use of adjustable push rods so that you can maintain proper valve geometry in the future.

*Deltacam of Tacoma Wa is the only company that refurbished worn rockers and adds a hardened insert.
* Smith Brother's will make you a custom set of (adjustable or non-adjustable) push rods for your engine, ensuring the highest possible efficiency from your lifters and valves.

There are more moves to increase your 4.0L's fuel economy but that's were I'd start.
 
Last edited:

gw33gp

Well-Known Member
U.S. Military - Veteran
TRS Banner 2010-2011
Ham Radio Operator
Joined
Aug 7, 2007
Messages
1,723
Reaction score
527
Points
113
Location
Costa Mesa, CA
Vehicle Year
2002
Make / Model
Ford
Engine Type
4.0 V6
Engine Size
4.0 SOHC
Transmission
Manual
2WD / 4WD
4WD
Tire Size
33"
I haven't seen anything about O2 sensors being replaced. They can start going bad and cause poor mpg without throwing a code. I know there is a way to test O2 sensors but I don't remember what it is.
 

Pauls14

Member
Joined
Jan 14, 2021
Messages
32
Reaction score
0
Points
6
Location
IL
Vehicle Year
1998
Make / Model
Ford Ranger
Engine Type
4.0 V6
Transmission
Automatic
2WD / 4WD
4WD
I haven't seen anything about O2 sensors being replaced. They can start going bad and cause poor mpg without throwing a code. I know there is a way to test O2 sensors but I don't remember what it is.
I can check voltage, thanks. I’ll try too
 

Uncle Gump

Token Old Guy
TRS Event Staff
TRS Forum Moderator
Supporting Member
VAGABOND
TRS Event Participant
Joined
Sep 17, 2018
Messages
13,691
Reaction score
13,146
Points
113
Location
Ottawa IL
Vehicle Year
2006/1986
Make / Model
Ranger/BroncoII
Engine Size
4.0L SOHC/2.9L
2WD / 4WD
4WD
My credo
Lead follow or get out of my way
Get the vehicle warmed up and get it out on the freeway. Will the truck get to and maintain highway speeds? Will it accelerate from highway speeds? If you answer yes to those questions... the cat is not plugged.

Now remember... rich fuel mixtures generate additional heat in the cats... because the cats are working double time trying to clean the exhaust. If you're rich and you don't fix it... it will certainly lead to the cats melting down.

I would pull the plugs and read them. Maybe you have a leaky injector(s). Do you even know what brand plugs you have installed? Do you know what the fuel pressure is? Does the engine start hard after warming up? Is your fuel pressure regulator leaking?
 

Pauls14

Member
Joined
Jan 14, 2021
Messages
32
Reaction score
0
Points
6
Location
IL
Vehicle Year
1998
Make / Model
Ford Ranger
Engine Type
4.0 V6
Transmission
Automatic
2WD / 4WD
4WD
Get the vehicle warmed up and get it out on the freeway. Will the truck get to and maintain highway speeds? Will it accelerate from highway speeds? If you answer yes to those questions... the cat is not plugged.

Now remember... rich fuel mixtures generate additional heat in the cats... because the cats are working double time trying to clean the exhaust. If you're rich and you don't fix it... it will certainly lead to the cats melting down.

I would pull the plugs and read them. Maybe you have a leaky injector(s). Do you even know what brand plugs you have installed? Do you know what the fuel pressure is? Does the engine start hard after warming up? Is your fuel pressure regulator leaking?
Truck runs good on highway. About plugs don’t know. Engine starts easy after warming up. I guess if leak I will feeling smell. But smell only burn dirty.
 

Uncle Gump

Token Old Guy
TRS Event Staff
TRS Forum Moderator
Supporting Member
VAGABOND
TRS Event Participant
Joined
Sep 17, 2018
Messages
13,691
Reaction score
13,146
Points
113
Location
Ottawa IL
Vehicle Year
2006/1986
Make / Model
Ranger/BroncoII
Engine Size
4.0L SOHC/2.9L
2WD / 4WD
4WD
My credo
Lead follow or get out of my way
In my experience... the cat(s) are probably not plugged. Because when plugged... the vehicle will experience a loss of power.

Logic also tells me with that kind of fuel mileage there is something wrong. Most things causing a rich condition will set a DTC... and/or have a drivability issue.

Does the check engine light illuminate with the key ON engine OFF?

Pull the plugs and see if they're fuel fouled... and see what brand they are. If they are anything but Motorcraft or Autolites... throw them in the trash can and buy the proper plug in either Motorcraft or Autolite.

I would also pull the vacuum line off the fuel pressure regulator and see if there is fuel in the line. If there is... the regulator is junk and needs to be replaced. I would still put a fuel pressure gauge on the system and check fuel pressure... and also see how fast it bleeds off pressure after you shut the engine off.
 

Pauls14

Member
Joined
Jan 14, 2021
Messages
32
Reaction score
0
Points
6
Location
IL
Vehicle Year
1998
Make / Model
Ford Ranger
Engine Type
4.0 V6
Transmission
Automatic
2WD / 4WD
4WD
In my experience... the cat(s) are probably not plugged. Because when plugged... the vehicle will experience a loss of power.

Logic also tells me with that kind of fuel mileage there is something wrong. Most things causing a rich condition will set a DTC... and/or have a drivability issue.

Does the check engine light illuminate with the key ON engine OFF?

Pull the plugs and see if they're fuel fouled... and see what brand they are. If they are anything but Motorcraft or Autolites... throw them in the trash can and buy the proper plug in either Motorcraft or Autolite.

I would also pull the vacuum line off the fuel pressure regulator and see if there is fuel in the line. If there is... the regulator is junk and needs to be replaced. I would still put a fuel pressure gauge on the system and check fuel pressure... and also see how fast it bleeds off pressure after you shut the engine off.
Yes, when I turn on, check engine light. Can I buy chipset gauge pressure? ( I saw on Amazon around 20$).
 

Pauls14

Member
Joined
Jan 14, 2021
Messages
32
Reaction score
0
Points
6
Location
IL
Vehicle Year
1998
Make / Model
Ford Ranger
Engine Type
4.0 V6
Transmission
Automatic
2WD / 4WD
4WD
In my experience... the cat(s) are probably not plugged. Because when plugged... the vehicle will experience a loss of power.

Logic also tells me with that kind of fuel mileage there is something wrong. Most things causing a rich condition will set a DTC... and/or have a drivability issue.

Does the check engine light illuminate with the key ON engine OFF?

Pull the plugs and see if they're fuel fouled... and see what brand they are. If they are anything but Motorcraft or Autolites... throw them in the trash can and buy the proper plug in either Motorcraft or Autolite.

I would also pull the vacuum line off the fuel pressure regulator and see if there is fuel in the line. If there is... the regulator is junk and needs to be replaced. I would still put a fuel pressure gauge on the system and check fuel pressure... and also see how fast it bleeds off pressure after you shut the engine off.
About regulator. I think if it broken, he couldn’t gives more than usual quantity fuel. Because fuel injectors give fuel. If it so much fuel, it will move fuel in back line to tank.
 

ericbphoto

Overlander in development
TRS Event Staff
TRS Forum Moderator
Supporting Member
U.S. Military - Veteran
TRS 20th Anniversary
VAGABOND
TRS Event Participant
GMRS Radio License
Joined
Feb 7, 2016
Messages
15,200
Reaction score
16,335
Points
113
Age
59
Location
Wellford, SC
Vehicle Year
1993
Make / Model
Ford Ranger
Engine Type
3.0 V6
Engine Size
3.0L
Transmission
Manual
2WD / 4WD
4WD
Total Lift
6"
Tire Size
35"
My credo
In theory, theory and practice are the same. In practice, they are different.
About regulator. I think if it broken, he couldn’t gives more than usual quantity fuel. Because fuel injectors give fuel. If it so much fuel, it will move fuel in back line to tank.
When the fuel pressure regulator fails, it leaks fuel into the vacuum line that actuates it. That leaked fuel is sucked into the intake manifold and is added to the fuel that the injectors put into the cylinders. This makes the engine run rich.
 

Pauls14

Member
Joined
Jan 14, 2021
Messages
32
Reaction score
0
Points
6
Location
IL
Vehicle Year
1998
Make / Model
Ford Ranger
Engine Type
4.0 V6
Transmission
Automatic
2WD / 4WD
4WD
When the fuel pressure regulator fails, it leaks fuel into the vacuum line that actuates it. That leaked fuel is sucked into the intake manifold and is added to the fuel that the injectors put into the cylinders. This makes the engine run rich.
I got it, thanks.
 

Pauls14

Member
Joined
Jan 14, 2021
Messages
32
Reaction score
0
Points
6
Location
IL
Vehicle Year
1998
Make / Model
Ford Ranger
Engine Type
4.0 V6
Transmission
Automatic
2WD / 4WD
4WD
In my experience... the cat(s) are probably not plugged. Because when plugged... the vehicle will experience a loss of power.

Logic also tells me with that kind of fuel mileage there is something wrong. Most things causing a rich condition will set a DTC... and/or have a drivability issue.

Does the check engine light illuminate with the key ON engine OFF?

Pull the plugs and see if they're fuel fouled... and see what brand they are. If they are anything but Motorcraft or Autolites... throw them in the trash can and buy the proper plug in either Motorcraft or Autolite.

I would also pull the vacuum line off the fuel pressure regulator and see if there is fuel in the line. If there is... the regulator is junk and needs to be replaced. I would still put a fuel pressure gauge on the system and check fuel pressure... and also see how fast it bleeds off pressure after you shut the engine off.
Today I’ve tried to find fuel pressure regulator and check vacuum line , but could not. Then i read in web about. There is only fuel sensor under hood (only too holes and connector), I guess if it doesn’t work I will see check engine. Second fuel pressure regulator or damper in the tank with fuel pump.
Also I saw on 4.0 OHV Explorer, there damper under intake in the fuel rail. (I have to take it apart, but I am not sure in ranger same or not)
 

ratdude747

Member
Supporting Member
Article Contributor
TRS 20th Anniversary
Joined
Aug 10, 2014
Messages
503
Reaction score
22
Points
18
Age
31
Location
Madison, IN
Vehicle Year
1995
Make / Model
Ford Ranger
Engine Type
4.0 V6
Engine Size
4.0L
Transmission
Automatic
2WD / 4WD
2WD
Tire Size
215/70R15
Today I’ve tried to find fuel pressure regulator and check vacuum line , but could not. Then i read in web about. There is only fuel sensor under hood (only too holes and connector), I guess if it doesn’t work I will see check engine. Second fuel pressure regulator or damper in the tank with fuel pump.
Also I saw on 4.0 OHV Explorer, there damper under intake in the fuel rail. (I have to take it apart, but I am not sure in ranger same or not)
It's on the Passenger side of the fuel rail (which is part of the upper intake stack). Hidden under/behind the throttle/cruise cable retainer assembly. You're looking for a red hard vacuum line.
 

Sponsored Ad


Sponsored Ad

Staff online

Members online

Member & Vendor Upgrades

For a small yearly donation, you can support this forum and receive a 'Supporting Member' banner, or become a 'Supporting Vendor' and promote your products here. Click the banner to find out how.

Truck of The Month


Kirby N.
March Truck of The Month

Recently Featured

Want to see your truck here? Share your photos and details in the forum.

Follow TRS On Instagram

TRS Events

25th Anniversary Sponsors

Check Out The TRS Store


Sponsored Ad


Sponsored Ad

Sponsored Ad


Amazon Deals

Top