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RPM fluctuates at idle (Mustang GT 2019)

Geo2019

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The title says it pretty much.
When idle cars RPMs going fluctuate somewhere between 600 to 800. They going up and down.
Is it normal.

Mustang, 2019, 20,000 miles.

Edit: No mods. Took to dealership and they said it is normal but somehow i doubt it.

Thanks.
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ice445

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Nope, not normal. Usually indicative of a misfire or vacuum leak. Have you done any mods? Scanned for stored or pending codes?
 

Joe 5.0

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The title says it pretty much.
When idle cars RPMs going fluctuate somewhere between 600 to 800. They going up and down.
Is it normal.

Mustang, 2019, 20,000 miles.

Thanks.
It's likely that you have a vacuum leak somewhere in the engine bay. I assume you're modded because you own a badass Mustang and you're on M6G, so take a look around the intake manifold, throttle body, air intake, etc. Also, reach out to your tuner with a datalog attached (if you're tuned).

It wouldn't hurt to scan the vehicle for codes as well--maybe there's a hidden code but no visible CEL light.
 
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Geo2019

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Nope, not normal. Usually indicative of a misfire or vacuum leak. Have you done any mods? Scanned for stored or pending codes?
No mods, but car did show light saying engine misfiring. Took car to the dealership, they cleared the light and said they did not find anything. And all is good.
 

ice445

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No mods, but car did show light saying engine misfiring. Took car to the dealership, they cleared the light and said they did not find anything. And all is good.
Well, I would argue that just because the dealer chose not to find it doesn't mean it's not still there. Try another dealership perhaps. There should be a stored code for which cylinder (or a P0300 for random).
 

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z6cyl

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RPM will fluctuate when the AC flicks on but not by 200rpm, thats nuts.
 

WildHorse

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Due for a oil change soon?
 
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My '19 had a similar issue, to the point that it was stalling at idle. First it was the fuel pump/sending unit that was diagnosed as bad; this was replaced but did not fix it. Return visit resulted in replacement of a failed fuel rail pressure sensor. So far so good. Car has a little over 5k miles. good luck.
 

Jaay_d5.0

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My rpms fluctuation when idling on my 2019 just a little bit almost every day has anyone solve the issue for this? Had my camphasers changed out , roush calibration update and vct cycle still fluacted after all these attempt fixes but atleast the car doesn’t stall anymore ever since i maxed the engine coolant when it was low. I was experiencing rough idles rpm fluctuations and stalling on my 19 gt 10r80. Now its just rpm fluctuations and im trying to solve the problem
 

NGOT8R

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I am modded and I have an issue with revs hanging on my 2019, not dropping like you guys are describing. Is this what you guys are experiencing?

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