yashagrawal

I have a 997.2, and recently went over a pot hole. Had a dent in the wheel, got it corrected. I have now noticed that when I am waiting at a stop light, or at rest with the engine running, the tach needle twitches about a 1-2 mm with the engine running. Is that normal, or am I being paranoid ?. I thought the needle was rock steady previously ?. If its not normal, what might be the cause ?. The Porsche advisor thought it was normal.

cluster_fsck

Ugh, sorry to hear about the pothole damage. After my 2011 997.2 C4 warms up, I notice a bit of bouncing at idle as the car burbles between 750-800 RPMs or so. It's normal. I'd be more concerned if you see RPMs take a dive at idle or swing erratically. I had the same concern when I first got my car and the tech said it was perfectly normal.

The engine RPMs are fluctuating a little as the car is telling you it wants to play!

Robocop305

I have a 997.2 and my RPM gauge fluctuate just like the above post.

MarcoRemius

Ditto, the gauge definitely moves at idle. In fact, to my surprise it's not a smooth needle movement. It's almost digital. I mean, I realize the gauge is electronic, but I expected a smoother movement. Eh, oh well.

Iceter

2009 C2 here. I get a bit of a fluctuation in my idle. This is not a problem.

TerpsRED

my needle bounces a lot at idle. I was worried at first, but it is totally normal.

StormRune

I've been playing around with a OBD-II interface device & app on my iPhone and can see that the idle on my engine is varying enough to explain this; confirming that the needle movements you are seeing reflects real RPM changes.

Spiffyjiff

yep. or hook it up to a durametric - definitely fluctuates. the tach (just like the rest of the gauges, esp water temp) are "dumbed down" so as not to alarm the citizens with their true readings.

yashagrawal

So a related question is what is the idle rpm in your NA cars, mine seems to be set at about 625-650 rpm range (997.2 C4S)

steve0827

'10 C2S and my idle also fluctuates a little bit.

Chrono

OT. I worked as an engineer at a place that made small environmental chambers for doctors' offices and hospitals. The staff at the offices were upset that the temperature changed when they opened the door. We made a firmware "upgrade" to lock the temperature reading upon door opening.

Back on topic, I have noticed while mildly accelerating that the needle is a bit herky-jerky as it climbs up. I attribute it to "not driving it right".