Hello...

I just bought a 2005 A4 2.0T quattro (auto, 22k miles, dealer certified pre-owned) a couple days ago and so far I love it- my first Audi. I've never owned a turbocharged car before, so forgive me if this question sounds naive...

My only complaint (right now just a minor annoyance) is that the turbo kicks in at a lower RPM than it really needs to. For example, in stop-and-go traffic or at a 4-way stop behind an alternating line of cars, each time I give the car a slight bit of gas to creep up one car length or thereabouts, the turbo kicks in and the torque delivered as a function of the accelerator position becomes very nonlinear. This occurs at only about 1500 or 2000 RPM. It's not so severe that I'm afraid I'll rear-end the car ahead of me, but it does force me to drive jerkier than I would like and I don't want my brakes to wear out faster because I use them to overcome the turbo at very low speeds.

I figure I can eventually adapt to this by "learning" the accelerator better, but I'm honestly not sure I should have to... does this sound like there is something adjusted incorrectly with my turbo, or is this the way all turbo engines feel? If it needs adjustment, is this something I can do myself, or is it a mechanic/dealership job? Is it common for the 2.0T engine? I thought the turbo was only supposed to kick on when you really asked for it- e.g. flooring accelerator, high RPMs, etc.

I didn't notice this when I test drove the car, since I was too busy seeing how it accelerated when I really punched it: much more fun than stop-and-go traffic ya know.

Thanks for your advice!
N

 

You can only really change it by changing the efficiency of the breathing of your engine. The turbo is driven by exhaust gasses, so if you make the engine breathe more efficiently (better exhaust manifold, better intake plumbing, cylinder head work to increase volumetric efficiency, etc), you'll spool faster. If you stuff a sweat sock into your intake piping, you'll limit the airflow and thus slow down the response of the turbo. It's not something that's controlled electronically as in, it'll stay out of boost below a certain throttle opening percentage. If you want to delay the response, get a bigger turbo - the larger inertia on it will require more airflow (hence higher RPM if you leave everything else as-is) to spool it up. Of course, the fun starts when it does start to boost. If you want to do this, you'll need supporting mods to keep from grenading the motor. Audi sized the turbo for near-instant response, so the car would feel like it had a larger, stronger naturally-aspirated engine, since the lag-and-surge feel of some turbo cars was considered to not be in keeping with its role as a near-luxury sport sedan.

 

the point of the stock turbo is to not have lag. Its is made to be like a nice v6 when accelerating and then a tame 1.8t when crusing. If you want power later and it to me more linear, you are going to need a slightly larger turbo and most likely journal bearing. Journal bearing turbos build boost slower than dbb turbos. If i was you, i would just learn to drive the car. It may take some time, but isnt to hard.

 

Are you coming from a Honda or something with V-tech? A turbo can't be adjusted in the way you want. As the previous guys said these cars have tiny turbos,with minimal lag for max torque. You'll get use 2 the low down boosting in a little bt,ease off the gas pedal as you gain revs,it's that simple.

 

Maybe try driving in some slippers or those socks with the little grip dots. You can get a better feel for where the pedal is and have more throttle control that way. Also, do you have the automatic or the manual transmission? If automatic you could try "creeping up" in 2nd gear or so. Otherwise, it's just a matter of learning the pedal on the car. These cars are built to be driven and may require more precise input than you are used to. Have fun!

 

I know the Audi's turbo can generate almost full torque at an extremely low rpm like around 1850s for my A6, and there is not much you can do except maybe chipping it so it will broaden the torque band.

 

Changing the exhaust housing of the turbo to one with a larger a/r can also change when the turbo spools up, but this isn't something that can be done to the stock turbo. Also porting the internal wg opening will increase lag since it then allows more air to pass thru it while it is open.