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Truck11 11-29-2012 10:31 AM

v8 - rough idle
'11 Limited 5.7l v8, 25k miles - getting a rough idle.
Happens when cold or warmed up. 'almost' Normal idle if I put it in park or neutral but very rough when in drive stopped at a light etc. hovering around 600 rpm.

Any thoughts? Could it be bad gas? wrong octane gas? Been happening for about a month now - so about 4 or 5 tanks of gas.

This is my wife's daily driver and she is about to drive from Northern VA to Boston this weekend (yay - more miles!) - She normally uses 87 octane. Told her to at least try 89 or 93 for the weekend to see if it helps any.

Appreciate any suggestions.

Scottina06 11-29-2012 10:34 AM

Re: v8 - rough idle
so when you pull to a stoplight for instance....the idle goes to 6k rpm? WOW

Truck11 11-29-2012 12:08 PM

Re: v8 - rough idle
Sorry - 600rpm. Thread fixed.
Had 6000 in my head about something else :-)

bill_de 11-29-2012 12:21 PM

Re: v8 - rough idle
The first thing I would do is throw some Techron injector cleaner in the tank.
Also, I think 30,000 miles is the interval for plug changes on the Hemi. You might need them a little sooner.

Truck11 11-30-2012 08:44 AM

Re: v8 - rough idle
Thanks Bill_de - I was thinking plugs also, but didn't realize it would effect the idle like that and not the overall performance (unless i just didn't notice it!)
I found the OEM plugs online at Rock Auto for $3.42 plus shipping- 5% coupon = $3.78 each. A little better than the $5 each elsewhere.

Will see what happens!

Truck11 12-11-2012 07:08 AM

Re: v8 - rough idle
Changed plugs last night - not too difficult. 26,140 miles, 15 months old. Still getting rough idle.
Any other thoughts?

ernestd 12-11-2012 07:35 AM

Re: v8 - rough idle
Did you look at your PCV valve?
It may be completely gummed up and plugged.
Good Luck.

JRoll1ns 12-16-2012 12:47 PM

This just happened to me, with the exception that the check engine light is now on and the mds is not working (no econ light). I have 26000 miles and the vehicle has been maintained every 3000 miles at the dealer sense the day I bought it.

Sent from my SCH-I535 using Tapatalk 2

Truck11 01-23-2013 08:33 AM

Re: v8 - rough idle
Dealer could not find 'anything' wrong and advised to run 93 octane for about 1000 miles to clear up the idle "as these Hemi's prefer 93" (BS!). done just over 1000 miles using 93 octane and still getting low/rough idle! (~600rpm). Same gas as I use in my FX and it doesn't have any issues.
Just install the BT catch can and the PCV valve was 'wet'.
Is the Throttle Body possibly the culprit and needs cleaning? (if possible and how to?)

ChrisWk 01-23-2013 09:31 AM

Re: v8 - rough idle
Throttle Body may be bad or needs to be clean. If your PVC was wet with oil the TB is got oil all over it too. I would get some TB cleaner spray some on a rag and wipe TB out or if you are handy take the TB off and clean it.

Truck11 02-01-2013 10:39 AM

Re: v8 - rough idle
Just picked up the Jeep from dealer yesterday - they said the target idle is 624 - and when connected to the computer, mine was 624-635 - so no issues! However, vehicle still feels like it is idling just a little low. Guess nothing more to do with it. :-(
I have cleaned the TB and the MAF sensor (different 'cleaning' products) - not very dirty.
They did however fix the Drive to Neutral 'Clunk' issue - software TSB as well as a spacer plate and filter TSB on the transmission. This resolved the issue and also got me a fluid change! Also updated the software on the radio and changed out the driver seat cushion due to it cracking on the side.

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