Economy and performance enhancements??? - Page 2 -
View Poll Results: How should I pursue my interests with this Jeep?
Stop. Save my money and buy a new one. 0 0%
Follow through with my plan so I can say I did it. 1 16.67%
Leave well enough alone and get all I can get from my daily driver. 1 16.67%
Have someone else do the work for me. 1 16.67%
Listen to the wisdom and proceed with caution. 3 50.00%
Voters: 6. You may not vote on this poll

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post #16 of 19 Old 12-23-2013, 06:06 AM
Registered User
1997 XJ Cherokee 
Join Date: Dec 2013
Location: Litchfield
Posts: 539
The oil pressure spec. for the 4.0 is this:

*Not less than 13 psi at HOT idle
*Between 37-75 psi OVER 1600 rpms

Yours sounds high at idle, what weight oil are you using?

An earlier comment you made was you were going to keep your engine temps cool to prevent lubricant breakdown etc, some old school mentality was the cooler the better, engines actually have a sweet spot that they run the most efficient, and it's not the coolest they can run. After re-reading the topic suggested, you'll see the greatest gains were running the engine closer to 210 degrees,(hence all the t-stat debate) todays lubricants are designed to withstand these temperatures, todays modern cars try to squeeze every last iota of economy and have sophisticated computer systems to achieve and maintain the correct warm up temp.

From one vet to another, sorry about your neck, also, your responses were coming off a little arrogant and defensive, don't read too much into everyone's text like they're talking down to you, myself included, you can't tell this merely from the text, a lot of times written word doesn't always come across right, and those who have responded, don't know you or you them, but were willing to assist, and you asked for info, and even posted a poll, which means you want opinions, problem is, most only want to hear what they consider positive opinions, negative ones can be informative as well. Sorry not bashing you, it's easy to misjudge others on a forum, you lack facial expression, tone of voice, and body language. I think more people get mad at people on forums they never would have in person.

And Welcome, now we need pics of your Jeep Damnit!

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post #17 of 19 Old 12-23-2013, 12:08 PM
Registered User
1992 XJ Cherokee 
Join Date: Oct 2012
Location: umatilla
Posts: 1,961
Most engines do not need anything extra for roller rockers. I just conferred with the old timers at my family machine shop. 4.0 no need to pull the head. They donr think it'll help economy enough to notice but will make acceleration smoother. They all agree that true zero timing gears and a mild cam are the best bet for middle of the road gains.
I've been told by electrical shops that keeping a strong charging system helps.
Of course losing the clutch fan helps too. I run Ford Taurus fans in place of clutch.
Of course trying to streamline a piece of plywood isn't cheap or easy.
I would think you could get the ecm reprogrammed for better injector management.
I've tried the re 3 stage programmer on stock and stroker 4.0's. 91-95 age range. No economy difference. It only helped with a trailer.
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post #18 of 19 Old 01-24-2014, 10:24 AM Thread Starter
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IodaJoey's Avatar
1993 XJ Cherokee 
Join Date: Dec 2013
Location: Kansas City
Posts: 9
First, thank you for all the feedback. All of it helps even the negative feedback. I apologize if I came off wrong. I did install the throttle body spacer and it reduced my mileage by 3 mpg. I got new shocks on all 4 corners and got an alignment, tire rotation and balanced and got back 3 mpg. I replaced the drip tarp that is held in by the plastic pushpins and mounts under the engine, kind of mixed in with all the tie rods and suspension stabilizers. After getting that buttoned back up I got another 2 mpg. So if I remember correctly I went from 16 mpg to 13 then back to 16 and am now at 18. I also had the transmission deep flushed because you could not tell the difference between the oil and the transmission fluid even after I had changed the fluid 3 times. I went through the transfer case,the differentials and removed the oil pan. I replaced the rear main seal, drained excessive fluid out of the transfer case. When changing the oil it calls for some little bitty filter by the book but I found that the FRAM PH8A is a much larger filter with more surface area and have been using that ever since. I have to add an extra half quart though and that's okay with me. It reduced my cold idle oil pressure tremendously. Any more ideas come up, feel free to let me know. Have a great day.

2012 Toyota Rav4,
2000 Chevrolet S-10 Extended Cab Flex
1993 Jeep Cherokee Sport

Semper Fi Marines
Have a great day all, Ben M.
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post #19 of 19 Old 01-24-2014, 10:51 AM
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Azzy's Avatar
2001 XJ Cherokee 
Join Date: Sep 2010
Location: Finleyville
Posts: 3,335
Wah! my eyes!

After lots of searching and looking.. I personally foudn the best bang for your buck on MPGs is obtained with gearing, a manual trans, and probably a merc diesel swap.

For how much most of the stuff would end up costing in the long run... Im planning on oil burner for the 30-40mpg.

Im the guy who makes new gauges, check out our gallery at
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mileage , performance , upgrades

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