2015 3.6L Cold Start ? - JKowners.com : Jeep Wrangler JK Forum
 
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post #1 of 12 Old 10-23-2014, 08:04 AM Thread Starter
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2015 3.6L Cold Start ?

I just purchased a 2015 Jeep Jk 2 door sport 6 spd manual ..

When I turn it on after sitting for a while it will turn on at about 1200 rpms then in like 15 seconds or so it will come down to idle. Is this normal?

My 2003 VW GTI VR6 did this but it was a recall.

Thanks!
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post #2 of 12 Old 10-23-2014, 08:22 AM
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That sounds normal to me! My 08 does the same thing.

08 JKU 6.0 LC8 6L80 Atlas 2 39" KM3's on Trilogy race beadlocks, prorock 44,rcv's arb front. rock jock 60 rear 40spline shafts,arb 5.13's and a bunch of other stuff
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post #3 of 12 Old 10-23-2014, 08:48 AM
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It's normal, my '14 does it

If it ain't broke, fix it 'till it is.
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post #4 of 12 Old 10-23-2014, 08:55 AM
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yep, normal. my '07 also does it but my rpm dont drop untill its 1/4 to 1/2 way warm

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post #5 of 12 Old 10-23-2014, 09:53 AM Thread Starter
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Thanks for the responses guys! Another question for Sixstring. Does your 3.6l have a slight ticking sound? Not like a ticking head problem, just a slight ticking sound when the jeep is on (obviously lol)
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post #6 of 12 Old 10-23-2014, 09:58 AM
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Quote:
Originally Posted by Hydrocon View Post
Thanks for the responses guys! Another question for Sixstring. Does your 3.6l have a slight ticking sound? Not like a ticking head problem, just a slight ticking sound when the jeep is on (obviously lol)
I noticed it before I changed the exhaust, now I can't really hear it

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post #7 of 12 Old 10-23-2014, 10:23 AM
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The 3.6 VVT all have the rattle / ticking sound on start up. Also the injectors are cracking at around 50 PSI so you hear it. Your GTI probably has more sound insulation than the Jeep. The head issue was a 2012 and real early 2013 problem.

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post #8 of 12 Old 10-23-2014, 12:51 PM
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Could just be the change from open loop to closed loop fuel control.
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post #9 of 12 Old 10-23-2014, 01:01 PM Thread Starter
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I figured it was normal I don't even have 500 miles on her yet lol. Just used to 4.0's and 258's so I know all the regular noises those should make. These new motors are a night and day difference. Although I miss the simplicity of the inline 6's. One last question before I stfu lol I currently have the 3.6 with manual and 3.73 gears pushing the original 29in tires and steel wheels. I have 286.75/16 duratracs and 16 level 8 wheels ready to go on. My first gear is practically non existant, when I get the bigger tires this should change a bit right? I should have a little bit of a longer 1st gear?
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post #10 of 12 Old 10-24-2014, 07:45 AM
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Quote:
Originally Posted by Hydrocon View Post
I figured it was normal I don't even have 500 miles on her yet lol. Just used to 4.0's and 258's so I know all the regular noises those should make. These new motors are a night and day difference. Although I miss the simplicity of the inline 6's. One last question before I stfu lol I currently have the 3.6 with manual and 3.73 gears pushing the original 29in tires and steel wheels. I have 286.75/16 duratracs and 16 level 8 wheels ready to go on. My first gear is practically non existant, when I get the bigger tires this should change a bit right? I should have a little bit of a longer 1st gear?
Yes. One inch of tire height will be about 100 RPM difference cruising down the road. You will want to correct your speedometer & odometer with something like a Pro cal. Look up one of the gear ratio charts and you can get a pretty accurate idea of what you will end up with.

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post #11 of 12 Old 10-24-2014, 03:01 PM Thread Starter
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Quote:
Originally Posted by scubatech View Post
Yes. One inch of tire height will be about 100 RPM difference cruising down the road. You will want to correct your speedometer & odometer with something like a Pro cal. Look up one of the gear ratio charts and you can get a pretty accurate idea of what you will end up with.
Thank you. Yessir I have already seen the chart. just curious about my 1st gear vs my 70mph rpm. but its common sense kind of a noob question I had there lol If my rpms will go down at 70 obviously my first gear with bigger tires wont rev up as fast.
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post #12 of 12 Old 10-28-2014, 06:58 PM
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I have the same set-up as you, 15 Man with 3.73 gears. I run 305/70/16 tires which measure out to be 32.1/8in tall with 40lbs of pressure. At 70mph I'm turning 2100 rpms. On the gear conversion chart it equals out to a 3.33 ratio. Which to me is perfect. 1st gear will be a whole lot better. Definitely buy a Pro-cal or other tool to change your speedo.

Last edited by Strider; 10-29-2014 at 07:34 AM.
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