When the 4.0L idles, the tach seems to fluctuate, not rough, but not solid either. I am not used to this as in my other cars in the past were rock solid with no movement. I wonder if this is normal:



I turned on the engine, let it idle for a few seconds, turn on the heating, rev to 2000 RPM, idle, turn off the heating, then turned off the engine. I just want to make sure it's not a precursor for something coming...

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Dough!
1982 MB 240D (died at 230k mi.)
1989 MB 190E 2.6 (sold at 155k mi,)
1999 BMW 328i Dinan Stage 1 (sold at 110k mi.)
2007 Acura TSX (going strong at 97k mi.)
2001 Jeep Cherokee Sport (59,869 mi.)

If it’s a very slight movement and you don't feel the engine loping, then I wouldn’t worry about it.

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2015 Ram Ecodiesel/Big Horn/4x4/Quad Cab
2016 Arctic Fox 22G/Onboard 2500 LP Cummins Onan Generator/160 Watt Solar Panel

I took the road less traveled. Now I'm LOST.