My '96 XJ Maintenance and MPG thread

[96Sportxj]

Been browsing the forum for a while and now that I decided to keep my XJ :cheers: (trucks are too damn expensive):flamemad: I figured I would keep track of my maintenance and log changes here. ::

I got this jeep from my parents when they upgraded to a new 4runner a couple years ago. And I have neglected her. :nono: So any tips or info will be much appreciated! :worship:

Specs and background

1996 Sport 4x4 4door 4.0L 158k Autotrans
Tires: Thunderer Ranger A/T R404LT235/75R-15C max psi 44, I keep them at 39psi and 44psi while towing 50+ miles

Use: 10min commute to work everyday and towing jetskis to the lake

MPG: 14-17mpg / 220ish miles per tank best ever 17.6 and I was towing! 95% of driving rpms are below 2200 with trans always in OD
Math is miles / gallons

Goals: 20mpg and reliability on long 300+ mile trips while towing

Maintenance and Issues so far:
04/10 trans, fuel filter and rear diff fluid changedone, new rear shocks2010-2015 normal maintenance and oil changes 05/16 - Oil change 10/40w
-No changes
08/16 - New CPS (That was a fun one to figure out..)
-No change in mpg or performance
11/16 - Thermostat broke and engine temp never got above 110F
-MPG 8mpg:bawl: I think i made it 90 miles on a full tank until the fuel light came on
11/16 - New 195 Thermostat engine temp 205ish
-MPG 11mpg 160 miles to fuel light
01/17 - New Bosch Plugs, wires, distributor cap, rotor and air filter
-MPG is deff better but still not great. So far at 190miles and fuel light still not on

Other issue that happens every couple months is no power to the starter.
I cleaned all of the terminals at the starter and battery but she requires a little tap with a wrench sometimes.

Plans: and please let me know if you think I am doing something wrong or have a better suggestion. :twak:

-New air temp sensor
-New Walker brand CAT 106$ ebay.com
-New Denso o2 sensors 60$ shop42a.com
-Jegs exhaust with 2.5" pipe 140$ jegs.com I think it is a dynomax rebrand?
-Seafoam treatment in gas tank and 91 octane fill up
-Seafoam treatment in oil followed by oil change after a couple fill ups
-Air shocks to keep the arse end up while towing
-Fuel filter
-New 4GA wires from battery to block and to starter
-New starter if it still has issues after wire change
-MAP sensor if fuel mileage still sucks


Anything else I should change or check at 150+ miles?

Also would it be worth buying a 10$ ob scanner? Does it give you any useful live data, or is it mostly for checking and clearing codes?

 

[trippled]

Exhaust is first on my list. I got5 mpg better with that. I would skip the premium fuel. A lot is blended with more ethanol which would drop your mpg. If you don't need it, don't use it. Good luck!

 

[Tim_MN]

The Jeep 4.0 L is old school and responds very well to basic hot-rodding, cat back exhaust, header, fresh air intake, and upgraded fuel injectors. Accelerate gently, and keep the brick shaped aerodynamics below 70 mph.

Use regular 89 octane fuel, genuine Jeep OBD sensors, NTK brand O2 sensors, and basic Champion or AutoLite spark plugs.

 

[96Sportxj]

Dang cant edit old posts?!

Filled her up today. 195 miles / 13.6 gallons = 14.33 mpg so getting better!
Filled her with 91 and put in a 16oz bottle of seafoam I normally run 87 but figured I would go with 91 when using the seafoam.

Anyone have any recommendations on a 2.5" downpipe for a decent pipe? Or should I stick with the factory size pipe since I am not running any other mods.

 

[96Sportxj]

Poured seafoam directly into the intake while reving her up then let her idle until the smoke cleared.

Added 5oz to the crankcase.

I also took my air box off and looked for the flap people say to remove and it is a clear shot to the intake.

 

[Anak]

For the starter, consider a new solenoid and new brushes. I did that on my '96 several years ago and haven't had a problem since.

Grimm's pictures are not showing in this thread, but mine are still there: http://www.naxja.org/forum/showthread.php?t=1115001

 

[96Sportxj]

For the starter, consider a new solenoid and new brushes. I did that on my '96 several years ago and haven't had a problem since.

Grimm's pictures are not showing in this thread, but mine are still there: http://www.naxja.org/forum/showthread.php?t=1115001

Great Idea! I like the idea of keeping those as a spare.

Any chance have you done anything to your transmission cooler to make it cool better?

A couple times while towing(1000ish pounds) up a steep incline 800ft to 5kft elevation change in a 90min drive and I have experienced what I tracked down to being tranny fluid leaking and causing a huge cloud of white smoke behind me as it burned on the exhaust pipe. after letting it cool and driving the rest of the way with the heater on it seemed fine. But I would like to keep it from happening again if you have any tips?

 

[Anak]

I have an AX-15, so I am no help there.

Sorry.

 

[Wayne Sihler]

If you tow --- get a cooler for the trans . B&M has a nice stacked plate design that fits well.My 96 is over 400,000 ,motor was replace at 400,000 well,because 400,000.
I have gotten over 19 mpg on a trip,loaded for a NAC Fest event.
Mostly now after many mods a good day will see 14 mpg

 

[96Sportxj]

If you tow --- get a cooler for the trans . B&M has a nice stacked plate design that fits well.My 96 is over 400,000 ,motor was replace at 400,000 well,because 400,000.
I have gotten over 19 mpg on a trip,loaded for a NAC Fest event.
Mostly now after many mods a good day will see 14 mpg

Did you ditch your stock tranny cooler or run both?

Side note: :smsoap: when you go from F to 3/4 tank after only 16 miles.. lol

 

[Wayne Sihler]

Did you ditch your stock tranny cooler or run both?

Side note: :smsoap: when you go from F to 3/4 tank after only 16 miles.. lol

I run both-I mounted cooler on pass side of radiator.
I get one round trip to work & back >75 miles

 

[96Sportxj]

I get one round trip to work & back >75 miles

 

[JeepNoob]

Dang cant edit old posts?!

Filled her up today. 195 miles / 13.6 gallons = 14.33 mpg so getting better!
Filled her with 91 and put in a 16oz bottle of seafoam I normally run 87 but figured I would go with 91 when using the seafoam.

Anyone have any recommendations on a 2.5" downpipe for a decent pipe? Or should I stick with the factory size pipe since I am not running any other mods.

Only one I know of is this one made by Walker- https://m.summitracing.com/parts/wlk-55277

If you're running a stock header, I'd just stick with the factory pipe. That being said, I would check for header cracks (they tend to crack around the collector area.) When that happens, the front O2 sensor sees a lean condition and the PCM fattens up the fuel injectors, leading to bad fuel economy and, eventually, a toasted cat. If the header's cracked, consider upgrading to a better header. At least a parts store one with flex joints and a lifetime warranty.

You've gotta pull the intake manifold to replace the header, so doing something like a port and polish or replacing it with a later model "horseshoe", equal-length intake manifold might be something to look into. Would also allow you to clean any crap out of the ports.

No need to run premium fuel either. I've actually seen an OEM service message advising against it. 87-octane is fine, 85 if you live in the mountains like me. Fuel economy might suffer a bit with E10.

 

[Wayne Sihler]

Remember you said "1/4 tank"

 

[96Sportxj]

Remember you said "1/4 tank"

That is impressive! reminds me of what I got in my civic.. Did the Jeeps come with different size fuel tanks?

So I got my walker cat and the inlet side is 2.5" outlet is 2" everything I have read says the jeep exhaust is 2.25".. lol

 

[96Sportxj]

If you tow --- get a cooler for the trans . B&M has a nice stacked plate design that fits well.My 96 is over 400,000 ,motor was replace at 400,000 well,because 400,000.
I have gotten over 19 mpg on a trip,loaded for a NAC Fest event.
Mostly now after many mods a good day will see 14 mpg

Going to change my oil soon and am thinking if you got 400k miles I want to run whatever you are running. What oil brand/weight/filter are you running in your xj? Also any other tips in making your engine last that long?

 

[Wayne Sihler]

Going to change my oil soon and am thinking if you got 400k miles I want to run whatever you are running. What oil brand/weight/filter are you running in your xj? Also any other tips in making your engine last that long?

OK. Nothing magic. You have a truck engine,use truck oils,not this new stuff for sewing machines.
10w-30 for the first couple 100 thousand,I would switch to Rotella T 15w-40 in the hot summer months then back to 10/30. I like Castrol High mileage in the green jug.
Quality wix/napa or pueroilator filter-change every 3000 miles
Dont overheat it,blow it out on an entrance ramp once in awhile

 

[96Sportxj]

OK. Nothing magic. You have a truck engine,use truck oils,not this new stuff for sewing machines.
10w-30 for the first couple 100 thousand,I would switch to Rotella T 15w-40 in the hot summer months then back to 10/30. I like Castrol High mileage in the green jug.
Quality wix/napa or pueroilator filter-change every 3000 miles
Dont overheat it,blow it out on an entrance ramp once in awhile

Thats it?! You don't sacrifice sheep to it once every 25k miles or run a gallon of seafoam through her every other tank of fuel?


Also what do you guys think about replacing the injectors? I have been reading about using the neon injectors and it seems that 50% of the people that do see 5HP and 10% MPG increase and the other 50% of people go back to using jeep injectors. Or should I clean the ones I have and call it day?

 

[dan1977p]

Thats it?! You don't sacrifice sheep to it once every 25k miles or run a gallon of seafoam through her every other tank of fuel?


Also what do you guys think about replacing the injectors? I have been reading about using the neon injectors and it seems that 50% of the people that do see 5HP and 10% MPG increase and the other 50% of people go back to using jeep injectors. Or should I clean the ones I have and call it day?
]

If your current injectors are dirty/broken/etc. change them. Otherwise, don't. I did mine and it smoothed out my idle and made it more responsive, but I'm certain it was because I had 215k miles on the previous injectors on an non-maintained motor.

 

[96Sportxj]

Made it a whole 178 miles on this tank and got 13.44 mpg. Hoping that it is worse because of the seafoam and the next tank will be better...

Swapped out starters yesterday! No longer have to drive in fear of not being able to restart. :rof:

New exhaust is on the way and going to change oil next weekend.