RPM bouncing-is this normal?

marzipan · Dec 8, 2011

Folks, I've got a 10 Golf TDI DSG(build date Sept '09) and lately I've been noticing that the tach needle flickers when driving at a consistent speed. It fluctuates up and down a bit. I've never noticed this before so I've been setting it on cruise control/flat surface and notice that at virtually any speed it wavers up and down. Is this normal? I don't "feel" anything but my car has experienced many of the false neutrals others have reported. My VIN falls in the range for the latest software update for DSG but they told me "yours isn't listed and you don't need it" by the dealer.

I never noticed the RPM bouncing before, but I never had a reason to look at it for long, either. I was having a lot of problem with rough idling and engine cut off while stopped, but that problem seemed to stop after giving it an Italian tune-up in conjunction with adding some Lucas upper cylinder cleaner with a fresh tank of D2.

Ideas? VW dealers don't want to deal with me or my questions (surprise!)

cheers!
mar

speedeep · Dec 12, 2011

Just noticed this on my 2010 (MKV) TDI Cup Edition (also CJAA engined) last week. I was idling at a stop light when the needle started bouncing a couple times from 800-1200 rpms. I don't recall hearing the engine change RPMS. It stopped after a couple bounces and the car accelerated normally. I plan to inquire about this a my 30k mile service in a week or two.

Build date: September 2010

-speedeep

golfTDI1 · Dec 15, 2011

It is not normal for the tach to do this under any circumstance, unless you were deliberately modulating the RPMs with your foot on the pedal. If the tach is accurate, meaning that the engine is actually doing the fluctuation, then you must diagnose the engine. A VCDS auto-scan should come up with something. Are there any MILs activated on the instrument cluster?

If the tach is operating erratically, meaning that the fluctuation is not actually representative of true engine RPM; then there is an electrical problem of sorts, whether it be a sensor, problem with the gauge, or loose connection.

RPM bouncing-is this normal?

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