Mine does it around 2700-3000 rpm, it is more apparent when Im not on the throttle very hard... what I find to be more annoying is the puff of smoke that fills my garage every 5th time I start it, or when Im in a parking lot and 10 people are watching you get into your new turbo and it puffs a cloud...

 

Where's that picture of the bunny with a pancake on it's head? I love this stuff, but sometimes it's way over my head. So much to learn and so little brain left.

 

I'm glad I read this post. One of the items I was going to have my service dept look into was the 'miss' or 'hesitation' I felt in these exact RPM ranges.

My last car was a 99 and had none of this, but I don't believe it had vario-cam.

 

Mine will hiccup somewhere around 3000-3200 when at cruise and no load. Someone else more educated in ECU systems, can confirm my theory or blast it to bits, but I throw it out there anyway.

I am running a UniChip (probably the lone hold out in this esteemd group ) and since it allows you to program it, my buddy, Alex and I have been able to experiment with different "maps." Actually, Alex knows what he is doing, I am just the lugnut, giving him feedback, from the drivers perspective.

It is my understanding that the "instructions" the ECU executes to control the engine are organized within defined RPM ranges in steps. As the RPM's increase the ECU reads the instruction for that rpm range, executes it, steps up to the next instruction and so on. Alex and my therory regarding the hiccupping is that when the rpm range and other conditions are just right, the ECU gets "caught" between one set of instructions and the next, stepping up and down from one to the other, resulting in the percieved misfire or hiccupping. This can only happen in a noticeable way if you are at a steady state cruise with no deviation in throttle inputs. Does that make sense to anyone else?

 

I know exactly what you all mean. Mine also will blow some smoke once in a while.

My 99 cab did it if I had slightly over-filled the oil AND had just driven it very hard before turning it off, like at the track.

This hasn't been the case the turbo though, as I immediately checked the oil the first time it did it and it hadn't been run very hard prior to parking it.

Quite embarrassing

 

It is a bit embarrassing to have that puff of smoke displayed at startup while a bunch of car guys (and their hot girl friends) are admiring the tt. Especially after they smile and look at each other in that knowing way that says: “boy did this guy get screwed�.

 

I also have the surge in my TT, but I never noticed it in the normally aspirated 996s (04 and 02).