Fluttering RPM while cruising at speed

[cra5h ov3ride]

Hey guys,

I just bought an '07 limited V8 4WD w/6 speed and have noticed what may or may not be a small issue. I feel as though I have searched the hell out of this to no avail so I'm asking for some assistance.

I've noticed that while driving at speed in the city (35), or highway (60-65) I get a small consistent fluttering of about 100 RPM up and down. This is noticeable on the tachometer and from my exhaust but I don't really feel it while driving.

I can't find anything on this on the internet so if anyone has any insight I would greatly appreciate it. My wife and I are leaving on a very long road trip at the end of the month and if this is serious I would like to fix it.

Thanks everyone,

Cra5h

 

[banditxp]

my brothers 02 grand Cherokee with the 4.7 does it and so does my 08 Ex with the 4.6
i think its something with modern day cars and the drive by wire and also the new trans's

 

[cra5h ov3ride]

So should I worry about it?

 

[turboranger91]

My money's on a small vacuum leak.

 

[cra5h ov3ride]

My money's on a small vacuum leak.

Forgive my ignorance but how do I go about diagnosing that?

 

[matsavol]

Torque converter slipping? You might want to try transmission fluid change. (Yes, Ford claims this transmission doesn't need fluid changes but I personally have witnessed significant improvement in 6R60 transmission operation after fluid change...)

 

[banditxp]

i wouldn't worry too much. mine did it at 42,000 miles and it does it at 111,000 miles now. its just a very small flutter and like he said you cant even feel it or hear it. brothers Jeep does it too before and after we swapped in a new trans around 220K miles.

If you feel it or feel power loss or something like that or you have a rough idol then yea. somethings wrong

 

[turboranger91]

Forgive my ignorance but how do I go about diagnosing that?

One way is to take a can of carb cleaner and spray along all the vacuum lines (with the engine running), and listen for changes in the idle. If the idle kicks up after you've just sprayed a spot... Replace that section of line. That's the easiest way I know of.

 

[hwystr]

Trans fluid

Search under converter shuffle, pretty common, many replace the converter, but I think its really just a fluid issue. Fixed mine with a fluid flush.