In general, normal idle for a DSM is 750 RPM. However, due to specifications for various components, an idle of 700-825 RPM displayed on your tachometer can be considered normal (in the absence of other symptoms). This specification applies to a fully warmed vehicle with all electrical accessories switched off (except Canadian vehicles, which have DRLs).
The car will have a higher idle under certain circumstances:
1G owners can expect 1.8L engines to idle at 800 RPM, while 2.0L (non-turbo and turbo) idle at 750 RPM. With the air conditioning on, automatics will drop to 650 RPM, while manuals will rise to 850 RPM.
2Gers will get 800 RPM out of their non-turbos, and 750 RPM from the 2.0 turbo and 2.4L engines. Again, this will rise to 850 RPM with the air conditioning on.
If your car does not idle exactly at these levels, or changes its idle slightly, occasionally or while driving, don't freak out. Few cars idle at precisely the designed level, owing to variations in climate and engine components. All of the above levels are rated at plus or minus 100 RPM, and the car will sometimes adjust the idle acording to driving conditions. If you don't have a problem with the car, leave the idle alone.
Some DSMers have problems with an unstable idle, or with their car being unable to maintain idle when coming to a stop. The first problem is a symptom of a badly set base idle, while the second in an indication of a broken speed sensor. Those with idle surge problems go here; those with cars that die at stoplights go here.
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