When clutch in the RPMs "pulse"

[openingshok]

Strange observation this past week. I have a 6 speed manual. When I put in the clutch the RPMs drop to idle or a bit above as expected, but then kind of pulse for lack of a better word. It will pulse back and forth between900 and 1100 RPM. It's not violent by any means, just very rythmic. Rarely but occasionally when I push the clutch it will rev a little (I'm off the gas) then drop to the pulsing. Once I am at a complete stop everything stabilizes and it idles at around 600 RPM, although there is a slight "lobeing" sensation in the engine. I know cars these days are tuned to idle VERY low for emissions purposes so idle rough, but this isn't a rough idle, just a "lub, lub, lub". Almost imperceptible.

Anyone else experiencing this? For reference it only has 2000 miles on the clock and clutch is fully to the floor.

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[dmcmurry]

No input, but I've also noticed similar uncommanded RPM changes with the clutch fully depressed, foot off the gas as I move it into or out of gear.

Following.

 

[AcesandEights]

Yep, annoyed the hell out of me at first. I guess it's "rev hang". My 2021 has gotten much better over time, but it still "hangs", not so much revs up as much, but still hangs.

 

[openingshok]

It doesn't seem to hurt anything, just not something I've seen in other vehicles so wonder if it's normal or a sign of an issue.

 

[openingshok]

Yeah mine hangs a bit also, but I'm talking more about once the RPMs drop out of the hang it pulses. You can't hear or feel it. Just noticed it on the tach. Strange.

 

[JLBoucher]

It's a tad of rev hang, indeed. It seems to get much better over time. Is your JL brand new?

 

[openingshok]

It's a tad of rev hang, indeed. It seems to get much better over time. Is your JL brand new?

BRAND new. 2000 on the clock. The thing I kind of compare it to is when crawling over rocks in 4low first gear when the engine encounters some resistance from the rock it adds a touch of power to climb over. This is similar but in neutral while coating. Once the vehicle is stopped the pulsing stops. There must be some kind of slight resistance in the drive line while rolling that cause the throttle to advance, maybe?

 

[JLBoucher]

BRAND new. 2000 on the clock. The thing I kind of compare it to is when crawling over rocks in 4low first gear when the engine encounters some resistance from the rock it adds a touch of power to climb over. This is similar but in neutral while coating. Once the vehicle is stopped the pulsing stops. There must be some kind of slight resistance in the drive line while rolling that cause the throttle to advance, maybe?

That's a good question. I tend to see it happening when the engine's cold. Same for you?

 

[openingshok]

That's a good question. I tend to see it happening when the engine's cold. Same for you?

No this was at operating temperature after 15 miles.

 

[AcesandEights]

Again, mine did it especially when new. I've got close to 9k miles on it now and it's much less frequent or noticeable. It was very annoying at first.

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