ny bruin

Just moved my car from garage to driveway to wash it. Then turned off the engine. The smell of something -- unburnt gas -- was pretty strong. Wow I never experienced this with my other cars.

No wonder why the gas mileage is so bad on this thing.

Tanner

It will be a bit rich until operating temperature increases, especially with the catalytic converter.

Timmay

I've driven it 20k miles to date.

Tanner

Of course given that the 4.2L is more than twice the size of our engines, the gas might be more exaggerated I'm guessing. I haven't seen a technical document on the 4.2 FSI yet but probably does something similarly...

<i>Cold Start Dual Injection

Dual injection is a special mode of operation for rapid heating of the catalytic converter.

To do this, a quantity of fuel is injected the intake stroke at approximately 300? before TDC of ignition. The fuel distributes itself homogenously due to the long gap before ignition. The second injection occurs at approximately 60? before TDC of ignition during the compression phase.

The rich mixture that forms around the plug means that timing can be retarded a considerable degree without affecting engine stability.

Dual injection also achieves stoichiometric (14.7:1) optimum air/fuel ratio. With the exhaust valves open, the exhaust temperature increases rapidly bringing the catalytic converter up to operating temperature 662° (350?C) very quickly (30-40 seconds).</i>

larrycr

because things tend to get fouled if the car is started and then shut off before it gets a chance to warm up. As I've posted before, all my S4s have suffered this to some extent. But it sounds like the RS4 is worse. My plan is to take it for a short drive before washing instead of just backing out of the garage and shutting it off.