Re: 04 Wrangler Spark Knocking - Dealer says use 93 octane. True?
 

I suspect that it is set this way to get better gas mileage for the sticker,
both with the low shift point and with the defaulting..

Thanks for this follow-up.
Tomes

"Wrangler x" <noemailplease@noemailever.com> wrote in message
news:ql5fuvsjmebc4iu0qdnqcuj2d08pq956b7@4ax.com...
> On Fri, 19 Dec 2003 09:45:26 -0500, Wrangler X <dont@email.me> wrote:
>
> >I am new to jeeps. I just bought a Wrangler X with an automatic as my
primary
> >commute vehicle. I have a terrible commute to work across two lane
mountain
> >roads that takes about an hour and a half every morning. I finally
realize that
> >I would not hate the commute so much in a jeep that had the doors off and
the
> >top down.
> >
> >So far, everything has gone great with the jeep, but then I noticed that
it is
> >having trouble when it gets warmed up good going up gentle hills. It
starts to
> >upshift too soon and ends up pinging. Mostly it happens when climbing a
gentle
> >hill. The engine will be at low RPM (around 1500) and in the highest
gear. It
> >hits the hill and does not downshift like it should. I have to mash the
> >accelerator pretty good to get it to stop, that or let off of the
accelerator to
> >make it downshift. Before it is up the hill, though, it shifts up into
the
> >highest gear and starts pinging again, so I have trouble holding constant
speed.
> >I either am accelerating or decelerating all of the time.
> >
> >The noise it makes is very gentle - it sounds like it is a mini-deisel
engine. I
> >don't think it is "hard knock" which I believe sounds like someone trying
to
> >bang a wrench against the hood.
> >
> >I took it to the dealer. They checked it with some computer thing (it
only has
> >3000 miles on it), and said that the gasoline here in Atlanta during
Winter is
> >the problem, that they (I cant remember which) add/subtract sulphur from
it,
> >making the jeep run incorrectly, and suggested I put 93 octane gas in it
to stop
> >the pinging.
> >
> >I did this and the pinging reduced, but did not stop.
> >
> >I've tried disabling overdrive. That works for a while (about five
miles), but
> >the Jeep's computer seems to adapt and start shifting up sooner after a
while to
> >counter-act the effect of having overdrive disabled.
> >
> >The dealership said 2004 Wranglers with three speed auto are all pinging
like
> >crazy, and nothing can be done.
> >
> >Can anyone confirm or deny this advice and the problem? What is the
difference
> >between hard knock and light knock?
> >
> >Any advice is appreciated.
> >
> >-Rob
>
> Here is a follow up to the story above for those of you wondering what
happened
> here. I appreciate the few responses I got.
>
> I went to a different Jeep dealership, and they said it sounded like
perhaps my
> transmission was the problem. The resident transmission expert hopped into
my
> Jeep with me and rode around town with me for 30 minutes listening to the
> engine. Nice guy - very smart - he seemed to know his ----.
>
> I approached a hill with overdrive engaged (it engages by default), and we
began
> to ascend. The transmission shifted from 3rd to 4th, and then RPM's
dropped to
> around 1200. The engine starting the pinging/spark knocking noise, and I
said,
> "THERE IT IS!"
>
> This is a summary of what he said.
>
> 1. That's not spark knock. That's "lugging." Your engine is working to
pull the
> hill. Spark knock on a jeep sounds like a the engine suddenly became a
huge
> diesel engine. You wouldn't have to listen for it. It will be loud.
>
> 2. 2004 Wranglers with automatics have a new feature this year: 4 speed
> transmissions. 2003 and earlier were all three speeds. The 2004 is a four
speed.
>
> 3. The ratio between gears 3 and 4 is not so great.
>
> 4. Overdrive is the use of that 4th gear.
>
> 5. When you are flying down the highway at 70mph, your engine doesn't lug
> because you are at high RPM's in overdrive.
>
> 6. When you are driving around town, you should disable overdrive as soon
as you
> start your car. Unfortunately, overdrive enables automatically on every
power
> recycle (turning it off and back on), so you have to push the button on
the dash
> every time you start your car. Only enable overdrive on the freeway with
no
> traffic for long distance trips.
>
> 7. Replacing the transmission will not help, as all 2004 transmissions are
four
> speeds, and all have the same problem. He says they have seen this a lot
in
> Jeeps owned by perceptive drivers. Most are sorta dumb and never notice
the
> problem. They just drive through it.
>
> 8. He said that flashing the controller software would help if Jeep
changes the
> settings at which the Jeep decides to upshift. Currently, it is set to
upshift
> from 3 to 4 way too soon, making overdrive use around town a pain. There
is no
> flash upgrade available at this time. He told me to keep checking because
one
> was expected eventually - so many people had complained about lugging in
4th
> gear. Recall expected...
>
> Otherwise, my Jeep is fine. We drove it around with OD set to off, and it
works
> great without the lugging. I wasn't aware that it reset to on with each
power
> recycle, so I thought it was compensating, when in reality the overdrive
was
> re-engaging.
>
> So, two things Jeep needs to get straight on automatic Wranglers:
>
> * Overdrive should default to OFF, you should push a button to turn it on,
and
> the setting should be persistent from one power cycle to another.
>
> * The controller software needs to be updated so that the Jeep doesn't
leave 3rd
> until reasonably high RPM's, to prevent lugging on hills around town.
>
> -Rob