Originally Posted by rotarygod

This is one of those issues that rotaries have always been set up to do. However it doesn't mean it's good for the engine. It isn't. When you first start a cold engine you don't really have an oil up in the engine. It's mostly in the pan. You start it and it takes a few seconds for the oil to reach every passage and bearing. It definitely isn't a good idea to spin the engine up faster right away during this period. It adds a small amount of wear to internal parts. The next thing is that you don't want the engine heating up too quickly as we have staggered cast iron and then aluminum housings which expand differently with temperature changes.

So why then does Mazda do this? Emissions! That's right, an environmentalist beaurocrat somewhere had enough of a say that it affects the longterm wear of your engine! Emissions standards say that your cat has to do it's job within so many seconds of starting. It can't do this when it's cold though so they need to heat it up as fast as possible but still slow enough not to kill the engine. A little wear is fine apparently. The engine revs up higher when it's colder because the cat has a greater temperature range to heat up to. They need the extra heat out of the engine. Thankyou EPA.

The RX-7's were done mechanically rather than electronically. We used to disable them and just let the car take a little longer to warm up when cold.