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Discussion Starter · #1 ·
Hi,

I am a new Mustang owner. First time having a Ford actually!
Mine is the 2016 Mustang V6 and I've been driving in the engine as specified and just passed 1300 miles.

While I am generally happy with the car I had a question about the engine. At both warm and cold it seems to have some shakes here and there at idle. A few every now and then can feel like a misfire. I can also see how the RPM needle dips a bit. From other cars I have been used to completely smooth idle. I heard someone say these engines aren't that refined, but I feel that's a weird statement on a new engine.

Before I take it to Ford for a check I'd like to just hear with you guys. Normal or not normal?

Thanks!
 

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The EXACT same thing is happening to my 1999 GT, it feels like a misfire or something and shakes the car more than regular idle should, but sets of no codes. I don't know what to do about it, unless it isn't a problem..!
 

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Use the recommended grade during the engine break in period..
Is it the brand or where your purchasing fuel from was my concern.
I tend to go to the high volume gas stations.
So fuel in ground is not getting condensation build up.
 

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Discussion Starter · #9 ·
Ah, hm.. I usually fill at Costco, otherwise at Shell. But from what I gather here it's not supposed to be like this, right?
Knowing that makes it easier to just bring it back to Ford to at least get a diagnose and see if anything comes up. It's been like this since brand new at 10 miles, but I thought I'd do the engine break in before taking it back, hoping it would go away.
 

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Your concern is well founded to me and across the web.
Googled "3.7 liter mustang rough idle" Tons of hits and videos.
Even at 1300 miles it should idle smooth.
Just for peace of mind head to a dealer, test drive another mustang and see if you feel or notice anything different.
When you do take it in for diagnosis and scan they will look at mode6 data to see if anything is tripping/counting but still within range that it is not setting CEL.
One of the hardest (driveabilty) to diagnosis without being in the car with a scanner doing a live drive data log.
 

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I heard someone say these engines aren't that refined...

That's ridiculous. The 3.7L is the best V6 I've ever owned.

I don't recall ever noticing revs dip, but I do recall a little bit of rumbling feel at idle. It never really bothered me because I liked how it was tuned as a package to feel more like a muscle car instead of smooth.

Are you talking about idling while the A/C is on?
 

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Have your harmonic balancer checked. I just had this issue on my 94 GT. After about 30 seconds of idle it would begin a serious lope with steep dips in the tach. For a few days it was fine once I put it in gear and began driving, but, it would start again whenever I came back to idle at a stop. One day the roughness got even worse and didn't go away when I began driving. I took it straight to my mechanic and he originally thought it might be some air sensor issue and bad air/fuel mixture. When he looked at it, my harmonic balancer had become slightly loosened and it was out of balance. My mechanic told me that it was good that I brought the car in quickly because an out of balance engine can very quickly, literally, shake itself apart.
 
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