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Old 05-07-2009, 01:48 PM   #2 (permalink)
Piwoslaw
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Join Date: Oct 2008
Location: Warsaw, Poland
Posts: 659

Svietlana - '05 307 SW
Diesel
90 day: 50.47 mpg (US)
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Quote:
Originally Posted by zman View Post
My question is the idle speed of the motor, will it change? And if so will it lower or increase? And am I going to see FE improvement when in idle?
The idle speed will remain the same. The ECU keeps a certain idle speed and adjusts the amount of fuel to stay there. You can observe this by suddenly turning on a large load when in idle (defroster, lights, etc.). The sudden load slows the engine down, but the ECU adds fuel and the rpms go back to normal.

If you take off your alternator or AC belt, then the load on the engine will be smaller, so less fuel will go into keeping it at idle speed.
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Quote:
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The more you drive, the less you think. Thats why I always take the bus.
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