My goal is to get 25+ mpg from my 99 XJ with 30 x 9.5 R15 ATs - Page 71 - JeepForum.com

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post #1051 of 3299 Old 11-25-2013, 04:04 PM Thread Starter
Charley3
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I haven't retested my gas mileage since getting my Jeep back from my cousin (who did the work), but I have been driving it, and I have some interesting news to report (even though I don't yet know what effect these things may have on gas mileage).

Since I switched (in the past) to 89 octane, it has idled a noticeably smoother and a little quieter, when cold or hot.

Then (recently) my cousin installed an AFE air intake, which breathes free'er. That made idle noticeably smoother when cold or hot.

Then (recently) I switched to 0/40 Mobil One, the idle became a little smoother and a lot quieter, especially at cold start. Way quieter than conventional 10/30, and a little quieter than synthetic 10/30 or 5/40. It likes 0/40. Oil pressure ideal cold or hot.
I recommend Mobil One 0/40 for moderate to cold climates, and Lucas 0/40 for moderate to hot climates. That's because if you compare their spec sheets, the M1 is slightly lower viscosity than Lucas (even though they are both rated 0/40).
Then (recently) I added some Zinc and Phosphorus additive to the oil, and idle became even smoother and quieter at cold start.
Specifically, I added one tablespoon of GM Assemby Oil additive, which is really a Z&P additive. There are other good brands of Z&P additive too, such as Lucas makes a Z&P additive. However, I think the GM version is more affordable and just as good as Lucas.
Then (recently) my cousin installed new 789 fuel injectors with 4 injection holes (Grand Caravan type) that I bought from Motorman on Ebay. That made idle even smoother and quieter yet, especially at cold start.

It's worth noting that my stock injectors were in excellent conditon with only 36K miles on them and were cleaned last Winter. So I'm not comparing nasty crusty stock injectors to new 789 injectors. I'm comparing stock injectors that are in excellent condition to new 789 injectors. The 789 are a noticeable improvement at cold start for smoother, quieter idle. I have not (yet) had the opportunity to test and compare gas mileage, nor have I put my foot into it to compare power (yet).
See post 213 for upgrade injectors explanation and part numbers for each year of Jeep 4L engine.
===

My 99 XJ 4L engine now idles very smooth and quiet, even at cold start. This morning it was 36F when I started my Jeep, and the 4L engine started easily, smoothly, and quietly, and then purred along as smooth and quiet as any modern engine. It's really amazing. No cold start clickity clacking valve lifters, nor ticking-clicking fuel injectors. Just the quietest and smoothest 4L I've ever heard, even at cold start on a 36F morning.

I've very happy with the results so far.

Edited in Later: It also starts easier. Starting is instant, even on a 36F morning.


Warning: I often edit my posts a few times to get them complete, or to correct errors.
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post #1052 of 3299 Old 11-25-2013, 04:18 PM
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Quote:
Originally Posted by Charley3
I haven't retested my gas mileage since getting my Jeep back from my cousin (who did the work), but I have been driving it, and I have some interesting news to report (even though I don't yet know what effect these things may have on gas mileage). Since I switched (in the past) to 89 octane, it has idled a noticeably smoother and a little quieter, when cold or hot. Then (recently) my cousin installed an AFE air intake, which breathes free'er. That made idle noticeably smoother when cold or hot. Then (recently) I switched to 0/40 Mobil One, the idle became a little smoother and a lot quieter, especially at cold start. Way quieter than conventional 10/30, and a little quieter than synthetic 10/30 or 5/40. It likes 0/40. Oil pressure ideal cold or hot. Then (recently) I added some Zinc and Phosphorus additive to the oil, and idle became even smoother and quieter, especially at cold start. Specifically, I added one tablespoon of GM Assemby Oil additive, which is really a Z&P additive. There are other good brands of Z&P additive too, such as Lucas makes a Z&P additive. However, I think the GM version is more affordable and just as good as Lucas. Then (recently) my cousin installed new 789 fuel injectors with 4 injection holes (Grand Caravan type) that I bought from Motorman on Ebay. That made idle even smoother and quieter yet, especially at cold start. See post 213 for injectors explanation and part numbers. === My 99 XJ 4L engine now idles very smooth and quiet, even at cold start. This morning it was 36F when I started my Jeep, and the 4L engine started easily, smoothly, and quietly, and then purred along as smooth and quiet as any modern engine. It's really amazing. No cold start clickity clacking valve lifters, nor ticking-clicking fuel injectors. Just the quietest and smoothest 4L I've ever heard, even at cold start on a 36F morning. I've very happy.
Sounds quite a bit like my set up and I've gained about 3

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post #1053 of 3299 Old 11-25-2013, 04:23 PM Thread Starter
Charley3
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Originally Posted by DunmerBoy View Post
Sounds quite a bit like my set up and I've gained about 3 (mpg).
I hope to gain some mpg, but I probably will never really know because I also added a winch and skid plates, for a combined weight increase of 325 lbs.

So I don't know how I can ever really test gas mileage for a valid comparison after adding weight and wind resistance at the same time I did the engine mods.

I'll try testing gas mileage, but what will it really tell us? If I can get about the same gas mileage as before (23 mpg highway at 65 mph), that'd be a huge victory (with the extra weight and extra wind resistance).
When I started this thread, I didn't intend to add skid plates or winch. Those mods came about during this thread. It screws up my gas mileage test to some extent, adding weight and wind drag in the middle of gas mileage mods, but my Jeep isn't just a road queen. It also needs to be trail ready too.

So now I'm going for best gas mileage possible with skidplates and winch, which I think will be around 23 mpg with my gas mileage mods.

i.e. - My gas mileage mods will still offer improvements compared to where I started (15 mpg highway), but some of that improvement is wasted on weight of winch and skid plates, and winch wind resistance. So 23 mpg might be as good as I can do. Though I plan to (eventually) make an aerodynamic winch cover. We'll see. I haven't restested gas mileage yet.
What I already know for sure, it runs a LOT better than when I began last Summer. It's so smooth and quiet now, the engine doesn't seem like a Jeep 4L engine anymore. It seems more like my Buick luxury car engine.

Warning: I often edit my posts a few times to get them complete, or to correct errors.
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post #1054 of 3299 Old 11-26-2013, 05:03 AM
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Winter gas will be arriving shortly if it hasn't already, so everyone should be aware that they'll be losing MPG just because of that.

Jealous of your quiet 4.0. Mine's not bad, but despite all my improvements, my engine has gotten noisier than when I bought it. I think the biggest culprit was the first Seafoam treatment I did, or perhaps more specifically, the high rev I did at the end of the Seafoaming--it's been a bit clickity-clackity especially when cold ever since

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post #1055 of 3299 Old 11-26-2013, 02:08 PM Thread Starter
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Mschi...

A mechanic friend told me to avoid all engine cleaners that work while engine running.
The exception is fuel injector cleaners that pour in gas tank. They probably won't hurt (nor help) anything.
I've had really good luck with professionally done MotorVac treatment. It's safe and effective.

Motorvac is done with engine NOT running. Cleaner forced through top-end of engine by a machine. Then change motor oil just in case some cleaner got in crank case. I have found Motorvac safe and effective.

Then I got a tune-up.

Then I did things described in post 1052.

Try those things. Particularly note the Z&P additive. It helps a lot with cold start lubrication.

Warning: I often edit my posts a few times to get them complete, or to correct errors.
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post #1056 of 3299 Old 11-26-2013, 03:46 PM
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Quote:
Originally Posted by Charley3 View Post
Mschi...

A mechanic friend told me to avoid all engine cleaners that work while engine running.
The exception is fuel injector cleaners that pour in gas tank. They probably won't hurt (nor help) anything.
I've had really good luck with professionally done MotorVac treatment. It's safe and effective.

Motorvac is done with engine NOT running. Cleaner forced through top-end of engine by a machine. Then change motor oil just in case some cleaner got in crank case. I have found Motorvac safe and effective.

Then I got a tune-up.

Then I did things described in post 1052.

Try those things. Particularly note the Z&P additive. It helps a lot with cold start lubrication.
I have a strong opinion with research to back it up on ZDDP, and I think I've shared it at some point in this thread even. I won't be using it, nor will I be tossing any other additives in.

A tune-up was done. I've done 703 injectors as you know, and I can't say with any certainty that they make a lick of difference in any way.

Seafoam is quite harmless and used by many including quite prominent and knowledgeable members of our own JeepForum. It's one of those things that people insist on indulging in controversy about, though, so I've given-up really trying to defend or "sell" it. Most Seafoam goes through the fuel to remove moisture and to clean the injectors or into the crankcase shortly before oil change. A third or less of a standard can goes through the cylinders--the process is well documented. I generally only use it as a fuel/injector cleaner and in the crankcase, but my XJ's history was unknown to me, so I assumed the worst and gave it a light freshening-up everywhere. Running SF through the intake isn't a regular occurrence for my vehicles, but it is for many others' vehicles, and when it is done right, no harm is done and often good comes of it.

I highly doubt the product had anything to do with my noise. It's more likely due to the high RPM used to clear deposits (possibly a little too high which is why it's a suspect) or even more likely a simple coincidence. Whatever the noise is, the only possible suspects are all harmless. I'm also quite observant and anal; while they don't bother me, I don't think I'd ever be able to say that a 4.0 runs quietly when, at the very least, I can always hear the injectors and evap purge solonoid clicking. On one hand, the little signature noises give it extra "Jeepy" charm. On the other, a "quiet" Jeep would be kinda neat.

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post #1057 of 3299 Old 11-26-2013, 04:06 PM
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Honestly I'm glad I didn't run seafoam through my xj, because when I took the intake manifold off it had a 1/4 inch thick tar like substance everywhere, and honestly the only thing that took it off was a tooth brush and seafoam, but imagine that tar like substance chunking off and entering your engine, I'm no expert but I'd assume that might be bad.
Now that it's all cleaned up I seafoam once every spring/summer.

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post #1058 of 3299 Old 11-26-2013, 07:10 PM
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Water can be ran through the vacuum line with similar results to sea foam

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post #1059 of 3299 Old 11-26-2013, 07:32 PM
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Quote:
Originally Posted by rebelbowtie View Post
Water can be ran through the vacuum line with similar results to sea foam
I've seen some water/methanol injection systems - increase in mileage and help keep clean, but you have to buy methanol & distilled water. Better than ethanol for power, but bad for fuel lines, etc, so it's generally injected separately

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post #1060 of 3299 Old 11-27-2013, 01:51 PM Thread Starter
Charley3
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Quote:
Originally Posted by mschi772 View Post
I have a strong opinion with research to back it up on ZDDP, and I think I've shared it at some point in this thread even. I won't be using it, nor will I be tossing any other additives in.

A tune-up was done. I've done 703 injectors as you know, and I can't say with any certainty that they make a lick of difference in any way.

Seafoam is quite harmless and used by many including quite prominent and knowledgeable members of our own JeepForum. It's one of those things that people insist on indulging in controversy about, though, so I've given-up really trying to defend or "sell" it. Most Seafoam goes through the fuel to remove moisture and to clean the injectors or into the crankcase shortly before oil change. A third or less of a standard can goes through the cylinders--the process is well documented. I generally only use it as a fuel/injector cleaner and in the crankcase, but my XJ's history was unknown to me, so I assumed the worst and gave it a light freshening-up everywhere. Running SF through the intake isn't a regular occurrence for my vehicles, but it is for many others' vehicles, and when it is done right, no harm is done and often good comes of it.

I highly doubt the product had anything to do with my noise. It's more likely due to the high RPM used to clear deposits (possibly a little too high which is why it's a suspect) or even more likely a simple coincidence. Whatever the noise is, the only possible suspects are all harmless. I'm also quite observant and anal; while they don't bother me, I don't think I'd ever be able to say that a 4.0 runs quietly when, at the very least, I can always hear the injectors and evap purge solonoid clicking. On one hand, the little signature noises give it extra "Jeepy" charm. On the other, a "quiet" Jeep would be kinda neat.
So you're saying Seamfoam didn't harm your engine, but the procedures in the Seafoam instructions did harm your engine. Huh.

You disagreed with almost everything I said, but which one of us has the quiet running engine?

Warning: I often edit my posts a few times to get them complete, or to correct errors.
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post #1061 of 3299 Old 11-27-2013, 01:59 PM
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Quote:
Originally Posted by Charley3
So you're saying Seamfoam didn't harm your engine, but the procedures in the Seafoam instructions did harm your engine. Huh
No, I'm saying I, personally, may have given it a little too much throttle when clearing it out (i.e. Would have been my error in executing the cleaning)

Quiet is subjective, and there are plenty of things that could vary between our two engines beyond our control especially given my XJ's 108k miles of completely unknown history when I got it. It runs perfectly--plenty of power, very smooth, very responsive, totally effortless starts, and very clean according to a recent emissions test. I'm very not interested in arguing oil/additives; it never goes anywhere, and I spend too much energy just researching to have much ambition left for debate. I'm not telling you to change--just saying I'm making a deliberate choice to abstain from the practices you've outlined

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post #1062 of 3299 Old 12-10-2013, 07:19 AM
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Quote:
Originally Posted by Charley3 View Post
I haven't retested my gas mileage since getting my Jeep back from my cousin (who did the work), but I have been driving it, and I have some interesting news to report (even though I don't yet know what effect these things may have on gas mileage).

Since I switched (in the past) to 89 octane, it has idled a noticeably smoother and a little quieter, when cold or hot.

Then (recently) my cousin installed an AFE air intake, which breathes free'er. That made idle noticeably smoother when cold or hot.

Then (recently) I switched to 0/40 Mobil One, the idle became a little smoother and a lot quieter, especially at cold start. Way quieter than conventional 10/30, and a little quieter than synthetic 10/30 or 5/40. It likes 0/40. Oil pressure ideal cold or hot.
I recommend Mobil One 0/40 for moderate to cold climates, and Lucas 0/40 for moderate to hot climates. That's because if you compare their spec sheets, the M1 is slightly lower viscosity than Lucas (even though they are both rated 0/40).
Then (recently) I added some Zinc and Phosphorus additive to the oil, and idle became even smoother and quieter at cold start.
Specifically, I added one tablespoon of GM Assemby Oil additive, which is really a Z&P additive. There are other good brands of Z&P additive too, such as Lucas makes a Z&P additive. However, I think the GM version is more affordable and just as good as Lucas.
Then (recently) my cousin installed new 789 fuel injectors with 4 injection holes (Grand Caravan type) that I bought from Motorman on Ebay. That made idle even smoother and quieter yet, especially at cold start.

It's worth noting that my stock injectors were in excellent conditon with only 36K miles on them and were cleaned last Winter. So I'm not comparing nasty crusty stock injectors to new 789 injectors. I'm comparing stock injectors that are in excellent condition to new 789 injectors. The 789 are a noticeable improvement at cold start for smoother, quieter idle. I have not (yet) had the opportunity to test and compare gas mileage, nor have I put my foot into it to compare power (yet).
See post 213 for upgrade injectors explanation and part numbers for each year of Jeep 4L engine.
===

My 99 XJ 4L engine now idles very smooth and quiet, even at cold start. This morning it was 36F when I started my Jeep, and the 4L engine started easily, smoothly, and quietly, and then purred along as smooth and quiet as any modern engine. It's really amazing. No cold start clickity clacking valve lifters, nor ticking-clicking fuel injectors. Just the quietest and smoothest 4L I've ever heard, even at cold start on a 36F morning.

I've very happy with the results so far.

Edited in Later: It also starts easier. Starting is instant, even on a 36F morning.

Been reading your entire post from start to finish this morning with great interest, a lot of good info for anyone wanting to improve mileage/running ability, but this was the first post that had me chuckle somewhat, with all the ...then it was quieter....made me think it must have originally sound like a chainsaw stuck on full throttle inside a metal garbage can
Just having fun, keep up the great work and thread!!

,======o00o.
/__||_l__l,\___\,___
l_--\__\__l_---[]llllll[]
_(o))_____(o))--o-))
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post #1063 of 3299 Old 12-10-2013, 07:24 AM
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Quote:
Originally Posted by Charley3 View Post
I haven't retested my gas mileage since getting my Jeep back from my cousin (who did the work), but I have been driving it, and I have some interesting news to report (even though I don't yet know what effect these things may have on gas mileage).

Since I switched (in the past) to 89 octane, it has idled a noticeably smoother and a little quieter, when cold or hot.

Then (recently) my cousin installed an AFE air intake, which breathes free'er. That made idle noticeably smoother when cold or hot.

Then (recently) I switched to 0/40 Mobil One, the idle became a little smoother and a lot quieter, especially at cold start. Way quieter than conventional 10/30, and a little quieter than synthetic 10/30 or 5/40. It likes 0/40. Oil pressure ideal cold or hot.
I recommend Mobil One 0/40 for moderate to cold climates, and Lucas 0/40 for moderate to hot climates. That's because if you compare their spec sheets, the M1 is slightly lower viscosity than Lucas (even though they are both rated 0/40).
Then (recently) I added some Zinc and Phosphorus additive to the oil, and idle became even smoother and quieter at cold start.
Specifically, I added one tablespoon of GM Assemby Oil additive, which is really a Z&P additive. There are other good brands of Z&P additive too, such as Lucas makes a Z&P additive. However, I think the GM version is more affordable and just as good as Lucas.
Then (recently) my cousin installed new 789 fuel injectors with 4 injection holes (Grand Caravan type) that I bought from Motorman on Ebay. That made idle even smoother and quieter yet, especially at cold start.

It's worth noting that my stock injectors were in excellent conditon with only 36K miles on them and were cleaned last Winter. So I'm not comparing nasty crusty stock injectors to new 789 injectors. I'm comparing stock injectors that are in excellent condition to new 789 injectors. The 789 are a noticeable improvement at cold start for smoother, quieter idle. I have not (yet) had the opportunity to test and compare gas mileage, nor have I put my foot into it to compare power (yet).
See post 213 for upgrade injectors explanation and part numbers for each year of Jeep 4L engine.
===

My 99 XJ 4L engine now idles very smooth and quiet, even at cold start. This morning it was 36F when I started my Jeep, and the 4L engine started easily, smoothly, and quietly, and then purred along as smooth and quiet as any modern engine. It's really amazing. No cold start clickity clacking valve lifters, nor ticking-clicking fuel injectors. Just the quietest and smoothest 4L I've ever heard, even at cold start on a 36F morning.

I've very happy with the results so far.

Edited in Later: It also starts easier. Starting is instant, even on a 36F morning.

Been reading your entire post from start to finish this morning with great interest, a lot of good info for anyone wanting to improve mileage/running ability, but this was the first post that had me chuckle somewhat, with all the ...then it was quieter....made me think it must have originally sound like a chainsaw stuck on full throttle inside a metal garbage can
Just having fun, keep up the great work and thread!!

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post #1064 of 3299 Old 12-10-2013, 12:45 PM Thread Starter
Charley3
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Still haven't retested gas mileage yet, but I've been driving a lot of short trips around town in cold weather from 19 to 30 degrees with heater on high.
It's even been down to 7F at night, but I stay home if below 18F (arthritis). We have high humidity here. So the cold really bites.
This Winter city driving should suck my gas guage down fast, but the needle barely moves.

I don't know what my mileage is right now, but it's obviously good for Winter city driving.

I need to make a grill cover and get electric fan to replace mechanical fan ASAP because with heater on my engine can't reach full op temp. It's running 200F. Full op temp is 210F.

Gas mileage on a 4L Jeep is best at 210F to 213F.

My 205F Gates thermostat is helping though. With a stock 195F stat is used to run 190F in Winter. The Gates 205F stat has it running 200F in Winter. So an improvement there.

However, the ACDelco/Motorad 205F stat is known to run about 5F warmer than Gates. So I bought an ACDelco stat, which will be installed ASAP.

I think I'm going to make my grill cover from plexiglass.

I'm also going to start dressing warmer so I can run heater less. That alone will help engine warm up more, which will help gas mileage substantially. Most important for me is warm gloves for that COLD rubber steering wheel.

Warning: I often edit my posts a few times to get them complete, or to correct errors.
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post #1065 of 3299 Old 12-10-2013, 12:56 PM Thread Starter
Charley3
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BTW - My new fuel injectors have really improved Winter driveability. Easier starting, smoother idle, quieter, better throttle response, and I suspect they are helping gas mileage.

Warning: I often edit my posts a few times to get them complete, or to correct errors.
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