Only getting 12-13mpg on stock JK - Page 3 - JeepForum.com
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post #31 of 47 Old 02-16-2016, 04:54 PM
jwmbishop
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Originally Posted by RAZORBILL View Post
Contaminating the oil with what?
Unburnt hydrocarbons - the pistons are cut oblong so that they are round at the 200 degree area. (the mass across the wrist pin vs perpendicular to the wrist pin heats and expands at different rate) This makes em oblong at room temp. so during warm up you get some fuel dilution past the rings.


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The wagon should, of course, be as light as possible, but strength should not be sacrificed to lightness, for on any but the regularly traveled roads, the wagon will get many a
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post #32 of 47 Old 02-16-2016, 05:14 PM
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Originally Posted by jwmbishop View Post
Unburnt hydrocarbons - the pistons are cut oblong so that they are round at the 200 degree area. (the mass across the wrist pin vs perpendicular to the wrist pin heats and expands at different rate) This makes em oblong at room temp. so during warm up you get some fuel dilution past the rings.
Why thank you! I guess you never want to buy a used car from me!

Previously owned: 80 CJ-5, 97 TJ,99 XJ, 95 YJ,10 JK Rubicon Unlimited, 10 JK Sport
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post #33 of 47 Old 02-16-2016, 05:38 PM
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Originally Posted by RAZORBILL View Post
Contaminating the oil with what?
Blow-by (the byproducts of combustion which include unburnt HC's and other compounds, which can combine with moisture formed during coming cycles to form acids and use up the additive packages in oils).

Blow-by is greatest during warm up when tolerances are loosest. Not to mention air: fuel ratios are greatest during cold start/warm up which adds to the equation.

The longer the warm up period, the more contamination and therefore the quicker the oil additives are used.

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post #34 of 47 Old 02-16-2016, 07:38 PM
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Quote:
Originally Posted by RAZORBILL
I knew I'd get the "you're doing it wrong" crowd on that one. Just asking the OP a question that may pertain to his situation. Wasn't looking for advice. Yep, don't like being in a cold vehicle and 9 times out of 10 I'm knocking the snow or frost of it while it idles. I like that as it warms up it actually assists in this too. I'm one of those crazy old people that actually clears the snow off my vehicle before driving. I'm not broke so I don't care about the gas. As for it somehow doing damage to the engine I'll beg to differ. Letting it idle for a few minutes is no better or worse then jumping in and driving it "easy" as many say for a few miles. I guess we should all turn our engines off when at a red light or stuck in traffic idling? I've warmed up every vehicle I have ever owned over my 51 yrs and never had a failure that could be remotely linked to letting it warm up. For every article or expert that says not to warm up an engine there is one that says you should. Clearly there is no undisputed truth one way or the other and probably never will be. Since it's my Jeep I'm the expert on this one.
Well since your soooo sensitive let me just shorten my reply that referenced your quote. "Letting your jeep sit there for that long does more than screw with the mpg readings it wreaks havoc on them"
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post #35 of 47 Old 02-16-2016, 08:52 PM
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Wouldn't sell just to save money on gas. Resale on Wranglers will typically make up more than the difference in fuel savings. If it is an environmental/energy concern then any true SUV or truck is a mistake. Are your tires sufficiently inflated for winter? Do you ease uphill and fly downhill? I wouldn't think idling would matter that much unless you have many short jaunts following a cold start.
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post #36 of 47 Old 02-16-2016, 09:31 PM Thread Starter
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Originally Posted by Spank
Sorry if I missed this in a previous post, but how many miles do you have on it? I didn't get the CEL for the bad cylinder on my '12 until I was well past 30k miles. I already had a 3.5" lift and 35's installed and I was getting insanely abysmal gas mileage. Getting the cylinder replaced jumped it back up into the two digit range appropriate for 4.10's on 35's and quite a bit of power was restored, too.
Mine has 22k miles.

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post #37 of 47 Old 02-17-2016, 08:11 AM
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Do you warm the jeep up??? That brings down your MPG fast. I warm my jeep up in the morning and my mpgs suffer like it was nobodies business.
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post #38 of 47 Old 02-17-2016, 11:18 AM Thread Starter
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Originally Posted by captainstabbin View Post
Do you warm the jeep up??? That brings down your MPG fast. I warm my jeep up in the morning and my mpgs suffer like it was nobodies business.

Not really, maybe only for about 30 sec or so.
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post #39 of 47 Old 02-17-2016, 12:27 PM
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Not really, maybe only for about 30 sec or so.
Well I am fresh out of ideas...
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post #40 of 47 Old 02-17-2016, 01:21 PM
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Silly question but are you driving around in 4wd? That will kill you MPG.

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post #41 of 47 Old 02-17-2016, 01:45 PM
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Buy a Pruis and move to a warmer climate.
Let me get this right, you buy a gas guzzler then complain about a pint of fuel burnt while warming it up.
Classic.

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post #42 of 47 Old 02-17-2016, 03:44 PM
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Okay - raven is a bit harsh but lets look at what he's really saying.

If you drive 30K per year (and that's a lot), that's 2500 gallons of fuel at 12MPG. that's 2000 gallons at 15. 500 gallons difference at 2.00 is 1000 bucks. the average is 12K a year (hence the 3 year 36K warranty). At 12k mile a year its 1000 gallons at 12, 800 at 15 - 200 gallons for 400 bucks.

How much are you willing to "pay to play"? (We can drive the wifes 30MPG Buick or my 22MPG Caddy so have a way to reduce my "play costs").

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The wagon should, of course, be as light as possible, but strength should not be sacrificed to lightness, for on any but the regularly traveled roads, the wagon will get many a
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post #43 of 47 Old 02-17-2016, 05:59 PM
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I do happen to drive 30k a year and I hate winter.
This boat of a winter beater only gets 17mpg hwy,but I do like it warm before I leave.
Guess I never worried about it.

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post #44 of 47 Old 02-17-2016, 06:15 PM
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Originally Posted by ravenworks View Post
I do happen to drive 30k a year and I hate winter.
This boat of a winter beater only gets 17mpg hwy,but I do like it warm before I leave.
Guess I never worried about it.
I wish i got the 12 the op is getting lol.

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post #45 of 47 Old 03-03-2016, 11:09 PM Thread Starter
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Update: I did take it to the dealer and told them about the bad gas mileage. They said they would have a tech look at it. I mentioned about the possibility of the bad left head and I do have the slight ticking sound also. They replaced the tappats and thats it. They acted like they never heard of the head issue and won't fix it unless it throws a code. Needless to say it still ticking. Time will tell if my MPG improves at all, but I sort of doubt it. This is easily the most frustrating vehicle I've ever had.
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