96 SL-2 high idle
#1
10-30-2010 | 03:34 PM
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96 SL-2 high idle
I have a 96 SL-2 with 150,000 miles. My son changed the rack and pinon steering. When I started it up it showed a code P0507 which is Idle Air Control. No code before the work was done. Idle speed now ranges between 1500 and 2500 RPM. On the back side of the throttle body are two connectors. The one on the back top has 2 wires. Occasionally when I disconnect the connector on the top back the idle will sometimes drop down to about 1000 RPM, other times when I disconect this connector nothing happens. I am not sure what that item is. When I start the engine the RPM was about 1200. Shortly it increased to 1500 RPM. Put in drive and RPM dropped to 850. Back in neutral the RPM is 1600. Disconnecting the Idle Air Control seemed to have no effect. Is the Idle Air Control the problem or is it something else. If it needs to be replaced is an after market part OK or should it be replaced with an actual Saturn part?
Thanks for your help.
Jim
Thanks for your help.
Jim
#2
10-31-2010 | 01:30 PM
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Posts: 2,748
From: Riveria of America
Here's what the vehicle manual says about the Idle Air Control:
An IAC (idle air control) motor is designed to adjust the engine idle RPM speed by opening and closing an air bypass passage inside the throttle body. The cars computer or ECM (electronic control module) receives information from various sensors and will output signals to adjust the IAC motor in or out to adjust engine idle speed by controlling engine idle air. An IAC motor can fail one of two ways, either the motor short circuits and stops working or the motor will develop high resistance and cause the IAC control motor to react slowly, either failure can cause the engine to stall at idle. When a trouble code scan is performed it sometimes won't always detect a failed or weak IAC motor. To check the IAC motor remove the unit, with the wires connected turn the key to the "on" position without starting the engine, the IAC should move in or out. If the IAC motor does nothing it has probably failed, replace it with a new unit and recheck system. Note: while the IAC motor is removed clean (use aerosol carburetor cleaner) the passages the IAC uses to control idle air speed, also inspect the IAC for a build-up on the seating (pointed) end and clean as necessary.
An IAC (idle air control) motor is designed to adjust the engine idle RPM speed by opening and closing an air bypass passage inside the throttle body. The cars computer or ECM (electronic control module) receives information from various sensors and will output signals to adjust the IAC motor in or out to adjust engine idle speed by controlling engine idle air. An IAC motor can fail one of two ways, either the motor short circuits and stops working or the motor will develop high resistance and cause the IAC control motor to react slowly, either failure can cause the engine to stall at idle. When a trouble code scan is performed it sometimes won't always detect a failed or weak IAC motor. To check the IAC motor remove the unit, with the wires connected turn the key to the "on" position without starting the engine, the IAC should move in or out. If the IAC motor does nothing it has probably failed, replace it with a new unit and recheck system. Note: while the IAC motor is removed clean (use aerosol carburetor cleaner) the passages the IAC uses to control idle air speed, also inspect the IAC for a build-up on the seating (pointed) end and clean as necessary.
#3
10-31-2010 | 04:31 PM
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Idle Problem solved
Hi OceanArcher:
Thank you for your response. Turns out when the rack and pinion was replaced the Air Conditioner line was bent slightly and was keeping the throttle cable from returning all the way against the stop. Kind of hard to find.
Thank you for your response. Turns out when the rack and pinion was replaced the Air Conditioner line was bent slightly and was keeping the throttle cable from returning all the way against the stop. Kind of hard to find.
Here's what the vehicle manual says about the Idle Air Control:
An IAC (idle air control) motor is designed to adjust the engine idle RPM speed by opening and closing an air bypass passage inside the throttle body. The cars computer or ECM (electronic control module) receives information from various sensors and will output signals to adjust the IAC motor in or out to adjust engine idle speed by controlling engine idle air. An IAC motor can fail one of two ways, either the motor short circuits and stops working or the motor will develop high resistance and cause the IAC control motor to react slowly, either failure can cause the engine to stall at idle. When a trouble code scan is performed it sometimes won't always detect a failed or weak IAC motor. To check the IAC motor remove the unit, with the wires connected turn the key to the "on" position without starting the engine, the IAC should move in or out. If the IAC motor does nothing it has probably failed, replace it with a new unit and recheck system. Note: while the IAC motor is removed clean (use aerosol carburetor cleaner) the passages the IAC uses to control idle air speed, also inspect the IAC for a build-up on the seating (pointed) end and clean as necessary.
An IAC (idle air control) motor is designed to adjust the engine idle RPM speed by opening and closing an air bypass passage inside the throttle body. The cars computer or ECM (electronic control module) receives information from various sensors and will output signals to adjust the IAC motor in or out to adjust engine idle speed by controlling engine idle air. An IAC motor can fail one of two ways, either the motor short circuits and stops working or the motor will develop high resistance and cause the IAC control motor to react slowly, either failure can cause the engine to stall at idle. When a trouble code scan is performed it sometimes won't always detect a failed or weak IAC motor. To check the IAC motor remove the unit, with the wires connected turn the key to the "on" position without starting the engine, the IAC should move in or out. If the IAC motor does nothing it has probably failed, replace it with a new unit and recheck system. Note: while the IAC motor is removed clean (use aerosol carburetor cleaner) the passages the IAC uses to control idle air speed, also inspect the IAC for a build-up on the seating (pointed) end and clean as necessary.
#4
11-14-2010 | 08:07 PM
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Joined: Jul 2010
Posts: 13
I have a 99 SL1 with the same exact issue, but I have no bent ac lines. I took it to a shop, the scan tool said Throttle position sensor, replaced that, didn't fix it. Replaced the IAC tonight, and it still idles high! Once I shut the engine off, and start back up, it will idle back down to 800. idles fine until I start driving again. Will get up to speed, push the clutch in, and idles about 2000 rpm. Shut the engine off, start back up, and idles back at 800.
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