Jeep Wrangler Forum - Reply to Topic
Jeep Wrangler Forum

Go Back   Jeep Wrangler Forum > TJ Jeep Wrangler Forum > TJ Tech Forum > lower fuel milage after tune up?

Join Wrangler Forum Today


Thread: lower fuel milage after tune up? Reply to Thread
Title:
  
Message:
Post Icons
You may choose an icon for your message from the following list:
 

Register Now

In order to be able to post messages on the Jeep Wrangler Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

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.



Additional Options
Miscellaneous Options

Topic Review (Newest First)
09-26-2007 02:46 PM
nregas1 Good deal.
09-26-2007 01:21 PM
dwdrums801 must have bein the computer learning the new air flow with the new o2 sensors cause I just filled up today and im gettin 13 mpg and thats driving really hard on the skinny pedal trying to keep up to my friends on a road trip who drive little sports cars....hopefully a week of driving normal again it will be at least 15 mpg
thanks for all the responses
09-26-2007 09:42 AM
richp
Quote:
Originally Posted by mud707 View Post
I had a similar problem, but it was caused by champions. Threw in a/c delco and problem fixed
I have not worked on tuning up anything newer than a 99, did jeep stick with champions when they went to the coil on plug ? I've also used autolite and ac/delco but the champion copper core truck plugs are more common around here. Plus the dealers sell them for maybe $.25 cents more than the parts stores so it's just as easy to get the plugs, cap, rotor, wires at one stop as I change them all when I do a tune up on either the XJ or the TJ's.
One thing I do intend on doing more often is replacing my injectors, last year I had the #3 stick open and it took out #3 cylinder, washed it right down at 80mph on the turnpike, had 330,000 miles on it but ran perfect till that happened. I put a jasper in and got new injectors from four oh motor sports, going to do them every 100K from now on. If I had not been in a hurry I would have gone with a stroker but I needed it faster then 3 weeks.
09-26-2007 08:25 AM
mud707 I had a similar problem, but it was caused by champions. Threw in a/c delco and problem fixed
09-26-2007 06:13 AM
richp
Quote:
Originally Posted by nregas1 View Post
FWIW. A while back I did a similar tune up my 98 TJ (less the O2 sensor), new wires and put some of the Bosch platinum 4 plugs in. Created all sorts of problems, including awful mpg (but not as bad as you're getting). Took to a buddy who is a ASE Master Tech at DC and he laughed at how much I just spent on the Bosch's and said the 4.0 didn't like them and I should have got the $1.50 Champions. He proceeded to tell me he's solved lots of unknown minor engine issues in the 4.0 by replacing the high-dollar plugs with some good ole Champions. FWIW.
The 4.0 and 2.5 both prefer plain old copper core champions, people tend to get defensive and then offensive when you tell them they wasted $30 or so on one of those exotic plugs. I ran NGK plats in my trooper and ended up with burned valves in less than 120miles.
09-25-2007 11:30 PM
nregas1 FWIW. A while back I did a similar tune up my 98 TJ (less the O2 sensor), new wires and put some of the Bosch platinum 4 plugs in. Created all sorts of problems, including awful mpg (but not as bad as you're getting). Took to a buddy who is a ASE Master Tech at DC and he laughed at how much I just spent on the Bosch's and said the 4.0 didn't like them and I should have got the $1.50 Champions. He proceeded to tell me he's solved lots of unknown minor engine issues in the 4.0 by replacing the high-dollar plugs with some good ole Champions. FWIW.
09-25-2007 11:10 PM
emilior 6 mpg seems to be a bit low even for a jeep. if you don't have a cel, and the engine's running smoothly, maybe there's something wrong with the odometer or the speedometer gear.

You're not running around in 4Hi right
09-25-2007 10:05 PM
jjseel http://www.wranglerforum.com/tj-chat...lugs-8593.html
09-25-2007 10:05 PM
dwdrums801
Quote:
Originally Posted by blktrax View Post
Or someone is doing a lot of in-town driving or 80-90 on the freeway.


If you did wires, why didnt you do a distributor Cap and Rotor.?



ran out of money thats next week
09-25-2007 10:04 PM
dwdrums801
Quote:
Originally Posted by Boulderv7 View Post
did you gap your plugs correctly?



plugs were suposto come pre gaped
09-25-2007 10:03 PM
dwdrums801
Quote:
Originally Posted by richp View Post
Disconnect the battery and ground out both leads to the frame WITH THE BATTERY DISOCNNECTED, IN FACT MOVE THE BATTERY ABOUT 10FT AWAY.
You want to drain any residual voltage from the system so you will loose your radio presets, etc. That way the ECU will go back to defaults and relearn.

did that....didnt help
09-25-2007 10:02 PM
dwdrums801
Quote:
Originally Posted by Rawkon View Post
thats horrible something isnt right. what gears do you have??

what plugs did you install??


stock gearing...not sure what it is exactly but i have the d35

i put bosch plugs in
09-25-2007 07:25 PM
Boulderv7 did you gap your plugs correctly?
09-25-2007 07:43 AM
blktrax Or someone is doing a lot of in-town driving or 80-90 on the freeway.


If you did wires, why didnt you do a distributor Cap and Rotor.?
09-25-2007 06:18 AM
richp Disconnect the battery and ground out both leads to the frame WITH THE BATTERY DISOCNNECTED, IN FACT MOVE THE BATTERY ABOUT 10FT AWAY.
You want to drain any residual voltage from the system so you will loose your radio presets, etc. That way the ECU will go back to defaults and relearn.
09-25-2007 04:31 AM
tobycat1 Crap man, I get 12 mpg pulling a boat up a steep grade hill with 33" tires at 8000 feet in my 4cyl( at 50 mph, pedal to the floor) 6mpg= big problem
09-24-2007 05:31 PM
Rawkon thats horrible something isnt right. what gears do you have??

what plugs did you install??
09-24-2007 05:08 AM
4Jeepn Just a guess, but perhaps the computer is learning the new air flow with the new o2 sensors? FWIW I get @13-14mpg with 35's and 4.56's
09-24-2007 02:24 AM
dwdrums801
lower fuel milage after tune up?

Changed my o2 sensors, plugs, wires and air filter and now im gettin only 6 mpg while before I was getting 10.....did I do something wrong? lol

this really sucks

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


All times are GMT -5. The time now is 08:22 AM.



Jeep®, Wrangler, Liberty, Wagoneer, Cherokee, and Grand Cherokee are copyrighted and trademarked to Chrysler Motors LLC.
Wranglerforum.com is not in any way associated with the Chrysler Motors LLC