TJ and octane.

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TX JEEPER

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Apr 29, 1997, 3:00:00 AM4/29/97
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Stuart Singer wrote:
>
> I'm curious what octane people are putting in their Jeeps. I have a
> TJ Sport. The service manager tells me to use 89 or 93. The manual
> says minimum 87 which suggests higher may be better? I do mostly local
> start and stop driving. BTW, I'm averaging 15.2 MPG so far at 1250
> miles.
>


I've been doing great with Conoco or Texaco 87 octane in mine-doing 1/4
hwy and 3/4 city driving.
I passed 12,000 miles today and my last tank got 20 mpg! But, have
thought about going to
the 89 octane, as it's knocking a little bit with the a/c cranking.
--
Bugs
Austin, TX (y'all)

TJ Sport/30"

My Little TJ Page at
http://www.io.com/guerilla/jeep/mytj.html

YO Jeep Jamboree pages at
http://www.io.com/guerilla/jeep/yo.html

Check out my company, Guerilla Audio
http://www.io.com/guerilla

Jerry Bransford

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Apr 29, 1997, 3:00:00 AM4/29/97
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> Stuart Singer wrote:
> >
> > I'm curious what octane people are putting in their Jeeps. I have a
> > TJ Sport. The service manager tells me to use 89 or 93.

Your service manager is one of many who doesn't understand octane. The
TJ's 4.0L engine is designed for 87 octane. Going to a higher octane
won't improve anything... not acceleration, power, cleanliness, etc.
All additional octane does is stop pinging, when the gasoline is
igniting prematurely for various reasons, ususually running too low of
an octane in a high-compression engine, which the 4.0L is not.
Occasional pinging (VERY occasional) when accelerating under load is
normal if it doesn't also occur in normal driving circumstances. Some
people feel higher octane makes their engine run cleaner, last longer,
etc. since be cause it costs more, it *has* to be better... it's not.
The only advantage to running higher octane than your engine needs is to
pump up the oil company's profitability LOL!

Regards,
Jerry
--
NOTE: To reply, remove the "NOSPAM" from my email address.
Jerry Bransford
PP-ASEL, C.A.P., KC6TAY
The Zen hotdog... make me one with everything!

jee...@sprynet.com

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Apr 30, 1997, 3:00:00 AM4/30/97
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I would not even worry about gas mileage your motor is not even broken in yet, awnser to your questio i use
87 but then again i have the 4cyl.

ed
jee...@spryet.com

John

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Apr 30, 1997, 3:00:00 AM4/30/97
to

Stuart Singer wrote:
>
> I'm curious what octane people are putting in their Jeeps. I have a
> TJ Sport. The service manager tells me to use 89 or 93. The manual
> says minimum 87 which suggests higher may be better? I do mostly local
> start and stop driving. BTW, I'm averaging 15.2 MPG so far at 1250
> miles.

I own a 97 TJ Sport with 4.0L and Auto transmission. I have to use 89
octane. If I use 87 octane, my engine pings on uphills and under
acceleration. I have had 4 seperate dealerships look at it and they all
say there is nothing wrong with it. They say it is bad gas. It's
amazing how not a single gas station in town has good gas, because I
have tried a few tanks full of 87 octane from every station in town.

Does anyone else have this problem? If so, has anyone's dealership
actually fixed it?

Jon Porter

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Apr 30, 1997, 3:00:00 AM4/30/97
to

Stuart Singer wrote:
>
> I'm curious what octane people are putting in their Jeeps. I have a
> TJ Sport. The service manager tells me to use 89 or 93. The manual
> says minimum 87 which suggests higher may be better? I do mostly local
> start and stop driving. BTW, I'm averaging 15.2 MPG so far at 1250
> miles.
>
I take it you don't live in California. Regular here is currently $1.51
a gallon and climbing, so the higher grades aren't an option for my TJ
4.0L. But seriously, most cars are made to run on 87 octane these days.
My TJ runs fine with it, and the reformulated gas here supposedly has a
little less kick in it than gas in other states. But let us know if you
notice any difference after trying one of the higher grades.

Andrew T. Smith

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Apr 30, 1997, 3:00:00 AM4/30/97
to imix4u...@io.com

TX JEEPER wrote:
>
> Stuart Singer wrote:
> >
> > I'm curious what octane people are putting in their Jeeps. I have a
> > TJ Sport. The service manager tells me to use 89 or 93. The manual
> > says minimum 87 which suggests higher may be better? I do mostly local
> > start and stop driving. BTW, I'm averaging 15.2 MPG so far at 1250
> > miles.
> >
>

> I've been doing great with Conoco or Texaco 87 octane in mine-doing 1/4
> hwy and 3/4 city driving.
> I passed 12,000 miles today and my last tank got 20 mpg! But, have
> thought about going to
> the 89 octane, as it's knocking a little bit with the a/c cranking.
> --
> Bugs
> Austin, TX (y'all)
>
> TJ Sport/30"
>
> My Little TJ Page at
> http://www.io.com/guerilla/jeep/mytj.html
>
> YO Jeep Jamboree pages at
> http://www.io.com/guerilla/jeep/yo.html
>
> Check out my company, Guerilla Audio
> http://www.io.com/guerilla

I was told that 87 was the proper octane to use. If you have a 4.0 and
you have an engine knock you may have an engine problem. The early TJ's
(built in 1996) had some problems that Chrysler had fixed in later
production. But there is a fix for it which Chysler faxed to my
dealership.

Mike Will

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Apr 30, 1997, 3:00:00 AM4/30/97
to

The gas problem is probably caused by the newer emissions requirements.
The octane is a burnability rating. It's fairly in depth how they decide
what octane a engine should burn. My 91 (which has a 1994 4.0L engine and
computer in it) doesn't seem to care too much what octane I put in it (87
or higher). My manual says that I can use anything above 87.
One possibility is that your local refinery is making oxygenated fuels,
which caused excessive pinging and a myriad of other problems. Generally,
all of the local gas stations will buy their fuels from the local refinery.
There aren't too many refineries around, so if your vehicle doesn't like
unleaded from one store, it probably won't like it from any others. The
difference between brands are the additives they have put into their fuels.
Another difference is the blend. Usually, there is a summer blend of fuel
and a winter blend, also oxygenated fuels can be ordered. Usually, the
"cheap" stores will buy the fuel out of season. It doesn't hurt anything,
but it really isn't the best running stuff, either (for the time). Here in
Washington, the refinery is in Anacortes (I think that's it, anyway). All
of the fuel for this area (and I hear it is shipped all the way to Oregon)
is manufactured there. It's then shipped to the holding facilities for the
various brands (BP, Texaco, Chevron, etc.).
Another possible cause is emissions related. Many people have mentioned
that the new 4.0L engines are running hotter than the older ones. While I
don't have any actual specifications about this, I understand that the
hotter the engine, the cleaner the emissions. My 4.0L runs at about 200
degrees (after it heats up). I have a mechanical gauge, so it's far more
accurate than the stock piece of sh** that came with it from the factory.
If I make the engine work a bit (long, steep freeway grades), it will heat
up a little, to maybe 205 degrees or so. I didn't have the mechanical
gauge when I had the four cylinder, but the factory gauge read about 210
degrees (once it was warmed up) regardless of summer, winter, off-road,
highway, or city driving.
The point I am trying to make here is that you may be forced to run more
expensive fuels to correct your problem. It is not Jeep's fault, you can
thank the EPA (Extra Pathetic Agency) for this wonder (much like you can
thank them for oxygenated fuels).

Mike.
--
Just remove the !! from my email address to send me mail.

1991 YJ 4.0L
31x10R15 Tires with Lock-Right Rear

There's more to life than gas mileage!


John <wran...@oztech.com> wrote in article <3366F2...@oztech.com>...


> Stuart Singer wrote:
> >
> > I'm curious what octane people are putting in their Jeeps. I have a
> > TJ Sport. The service manager tells me to use 89 or 93. The manual
> > says minimum 87 which suggests higher may be better? I do mostly local
> > start and stop driving. BTW, I'm averaging 15.2 MPG so far at 1250
> > miles.
>

Rudy Schmidt

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Apr 30, 1997, 3:00:00 AM4/30/97
to

TX JEEPER wrote:
>
> Stuart Singer wrote:
> >
> > I'm curious what octane people are putting in their Jeeps. I have a
> > TJ Sport. The service manager tells me to use 89 or 93. The manual
> > says minimum 87 which suggests higher may be better? I do mostly local
> > start and stop driving. BTW, I'm averaging 15.2 MPG so far at 1250
> > miles.
> >
>

> I've been doing great with Conoco or Texaco 87 octane in mine-doing 1/4
> hwy and 3/4 city driving.
> I passed 12,000 miles today and my last tank got 20 mpg! But, have
> thought about going to
> the 89 octane, as it's knocking a little bit with the a/c cranking.
> --
> Bugs
> Austin, TX (y'all)
>
> TJ Sport/30"

Interesting thing. I know a guy who worked for a while as an assistant
manager of an Exxon station. He told me that they paid the same for all
grades, just marked it up at the pump.

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