1999 Sport Fuel Mileage... Lost!
#17
CF Veteran
Join Date: Feb 2011
Location: Bergen County, New Jersey U.S.A.
Posts: 3,074
Likes: 0
Received 0 Likes
on
0 Posts
Year: 1990 Laredo
Model: Cherokee
Engine: 4.0 Inline 6 Renix
#18
A buddy of mine was stuck in the mid 11's mpg-wise. We looked over/cleaned and replaced all the parts you listed and nothing helped. Until he noticed his motor mount on the drivers side was pretty worn. Not broken completely, but well on its way. We replaced them with brown dog mounts and oem replacement for the trans mount. He jumped up about 1.5 mpg immediately. It didn't magically give him 20 mpg, but with our rigs every bit helps right !
#19
CF Veteran
Join Date: Feb 2011
Location: Bergen County, New Jersey U.S.A.
Posts: 3,074
Likes: 0
Received 0 Likes
on
0 Posts
Year: 1990 Laredo
Model: Cherokee
Engine: 4.0 Inline 6 Renix
Hmm... Is your jeep coming up to temperature ? Running in the 195 210 area... If its running to cold that will also have bad gas mileage ...
#20
Herp Derp Jerp
Join Date: Nov 2011
Location: Parham, ON
Posts: 18,251
Likes: 0
Received 13 Likes
on
12 Posts
Year: 1999
Model: Cherokee
Engine: 4.0L OBD-II
A buddy of mine was stuck in the mid 11's mpg-wise. We looked over/cleaned and replaced all the parts you listed and nothing helped. Until he noticed his motor mount on the drivers side was pretty worn. Not broken completely, but well on its way. We replaced them with brown dog mounts and oem replacement for the trans mount. He jumped up about 1.5 mpg immediately. It didn't magically give him 20 mpg, but with our rigs every bit helps right !
#21
A lot of car have "adaptive driving" meaning that a car will learn its driving conditions and adapt to either fuel milage or performance. you can reset the ecu(by doing this, you also reset the fuel trim). give it a try and see what happens
#22
Senior Member
Thread Starter
Join Date: Jan 2012
Location: Indiana
Posts: 635
Likes: 0
Received 2 Likes
on
2 Posts
Year: 1999
Model: Cherokee
Engine: 4.0
trans mount was replaced and took care of the banging from the exhaust but no mileage improvement. Motor mounts are for sure on the list of one of the next things. the ECU was reset when the 02sensors and injectors went in. and have run two tanks since then so definately enough time to get the computer to relearn the trim
Temp is good, even when running the computer to take a peek at live data its running steady about 200-205, so i know the computer is seeing the correct temp.
this one has got me puzzled since all the normal culprits of poor mileage have been taken care of,
Temp is good, even when running the computer to take a peek at live data its running steady about 200-205, so i know the computer is seeing the correct temp.
this one has got me puzzled since all the normal culprits of poor mileage have been taken care of,
#23
CF Veteran
Join Date: Dec 2012
Location: York, PA
Posts: 4,169
Likes: 0
Received 6 Likes
on
6 Posts
Year: 1998
Model: Cherokee
Engine: 4.0
It is certainly serviceable. You just have to drop the tank. I have plans to replace the whole thing due to my gauge jumping around and not really being accurate.
#24
Senior Member
Thread Starter
Join Date: Jan 2012
Location: Indiana
Posts: 635
Likes: 0
Received 2 Likes
on
2 Posts
Year: 1999
Model: Cherokee
Engine: 4.0
you are right is is serviceable but does anyone really want to drop the tank for a filter? I understand your position being how the gauge is off or not working correctly. What i was saying is that in a normal maintenance schedule of things changing the fuel filter isn't really a feasible idea.
#25
CF Veteran
Join Date: Dec 2012
Location: York, PA
Posts: 4,169
Likes: 0
Received 6 Likes
on
6 Posts
Year: 1998
Model: Cherokee
Engine: 4.0
you are right is is serviceable but does anyone really want to drop the tank for a filter? I understand your position being how the gauge is off or not working correctly. What i was saying is that in a normal maintenance schedule of things changing the fuel filter isn't really a feasible idea.
#26
Senior Member
Join Date: Jan 2011
Location: Joliet, Il
Posts: 730
Likes: 0
Received 2 Likes
on
2 Posts
Year: 1996
Model: Cherokee
Engine: HO4.0 I6
Heard that! But I'm subscribing as well. My 96 is riding on 2" of lift and on the same set of tires. I'm around 14 mpg. My 88 I was kicking it with 18 mpg's.
#27
Member
Join Date: Sep 2011
Location: hollywood florida.
Posts: 110
Likes: 0
Received 0 Likes
on
0 Posts
Year: 2000
Model: Cherokee
Engine: 4 litre
How was your mpgs before those 784 injectors? I heard their flow rate is to high and even after the ecu it'll spray too much fuel