What is proper idle speed for 2004 TJ 4.0L with auto?

I've got a 2004 Rubicon with the 4.0 engine and automatic transmission. It has about 1000 miles on it. It runs great, but after it is warmed up the idle goes down to about 400-450 RPM's on the factory tach. At that speed it is a little rough, but not bad, and it never stalls or does anything out of the ordinary. If I turn on the AC or put it in neutral it speeds the idle back up to about 600. I suppose I'm being over sensitive becuase this is my first new car for a long time, but I'm used to seeing engines idle about 600 to 800. Idle speed is controlled by the computer and I can't even find the speed listed in the factory serice manual or on the sticker under the hood.

Is what I'm seeing normal for the Wrangler?

Thanks for your time.

Reply to
Lee
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Lee did pass the time by typing:

Sounds normal for the I6, maby a bit low. The dealer can adjust your the idle.

Reply to
DougW

Sounds low to me too - I believe it's supposed to idle at 600, but can't find a source. I know it's a sign of the times, but does anyone else feel a little sad knowing it's common place to have the dealer adjust something a simple as the idle rpm.

____________________ HomeBrewer

76-81-85CJ7 All in one Jeep
Reply to
HomeBrewer

HomeBrewer did pass the time by typing:

A quick check of my 93 service manual shows 600 base with 800 if the AC is on.

Reply to
DougW

Unfortunately, the 2004 service manual doesn't even show an idle speed and says "all idle speed functions are controled by the IAC (Idle air controller) motor through the PCM. It's the factory service manual, and has no instructions at all for adjusting the idle.

I'll probably take it to the dealer for the first scheduled service and mention it to them at that time, but it sounds like there's not much that can be done unless there are deffective components.

Thanks for tak>HomeBrewer did pass the time by typing:

Reply to
Lee

Lee did pass the time by typing:

Same thing with the 93, there is no base idle adjustment. (although there is a set screw on the throttle body that can be tweeked a tad. Thing is the IAC motor will simply be driven shut and could stick)

Reply to
DougW

Reply to
L.W.(ßill) Hughes III
96 JGC 750 Rpm

Since it's starting again ;)

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-- LE CLONE

279 Notre-Dame Gatineau, Qc J8P 1K6 (819) 643-0511 SANS FRAIS 1 888 643 0511
Reply to
Le CLone

forgot to say I6 4 Liter

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-- LE CLONE

279 Notre-Dame Gatineau, Qc J8P 1K6 (819) 643-0511 SANS FRAIS 1 888 643 0511
Reply to
Le CLone

A friend had a similar problem with his 2004 Grand Cherokee 4.0 and automatic, only his seemed to be idling too fast and ran rough when stopped with the brake applied. Turns out there was a service bulletin for his that specified the idle should be set to "744 RPM" - yes you read right, "744"!!). That little operation fixed his complaint.

Reply to
Jack Carter

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