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Hi, the SL uses an idle speed valve and control unit. There is no idle speed adjustment on this car. To increase the idle speed you can clean the idle control valve and clean the throttle body. Aside from that you will need to replace the idle valve and control unit to increase the idle speed. Keep in mind that the normal idle speed for this car is 650 rpm in neutral and 500 rpm in drive. One trick that you can use to fool the system is to disconnect the oil temperature sensor on the oil filter housing. This will raise the engine rpm approximately 100 rpm.
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