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Discussion Starter #1
We love our new 2014 Grand Cherokee Overland with diesel. My minor question is this: what should the idle rpm be? Ours is about 800 rpm, which seems somewhat high, and if I release the car on level ground in idle it moves at about 6 miles per hour, which also seems somewhat high. I would think that in city driving I would get higher fuel efficiency if the engine is running slower when stopped at a traffic light, which is why I'm asking. Thanks for any enlightenment that can be offered.
 

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Thanks much for the document, but I note that it is dated 2011. I'm not sure that the diesel in the 2014 Grand Cherokee is the same. I asked a guy in the service department of my Jeep dealership and he claimed that 800-1000 rpm is the correct idle speed. But I can't shake the feeling that the idle is too fast.
 

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I did see the date on the document, but the specs are at the same so I was pretty sure it's same engine. I check mine today and write back later.
 

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I requested from my Jeep dealer the specs on the 2014 diesel engine, and indeed the idle speed (warm) is supposedly 650 rpm. However, when I pointed out that according to my tachometer the warm idle speed is 800 rpm it was claimed that it doesn't matter, and besides it is impossible adjust the idle speed, which sounds very strange.
 

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Re: Adjusting idle speed. That's actually not surprising. They might be wrong, but it's all controlled electronically these days. Even gas pedals are becoming fly-by-wire, no longer directly connected.

I would make sure that you have all of the software upgrades on your Jeep. Sometimes you find undocumented fixes.

The dealer should be able to read the RPM via the ODBC II port. You're tach could be reading wrong.
 

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I requested from my Jeep dealer the specs on the 2014 diesel engine, and indeed the idle speed (warm) is supposedly 650 rpm. However, when I pointed out that according to my tachometer the warm idle speed is 800 rpm it was claimed that it doesn't matter, and besides it is impossible adjust the idle speed, which sounds very strange.

Bruce, engine idle speed is controlled by the powertrain control module (PCM). I don't believe there's any manual adjustment to that other than reflashing the module.
 

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Re: Adjusting idle speed. That's actually not surprising. They might be wrong, but it's all controlled electronically these days. Even gas pedals are becoming fly-by-wire, no longer directly connected.

I would make sure that you have all of the software upgrades on your Jeep. Sometimes you find undocumented fixes.

The dealer should be able to read the RPM via the ODBC II port. You're tach could be reading wrong.

The GC has a fly-by-wire throttle.
 
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