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1992-1999 Series I L27 (1992-1994 SE,SLE, SSE) & Series II L36 (1995-1999 SE, SSE, SLE) and common problems for the Series I and II L67 (all supercharged models 92-99) Including Olds 88's, Olds LSS's and Buick Lesabres Please use General Chat for non-mechanical issues, and Performance and Brainstorming for improvements.

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Old 12-28-2004, 09:05 PM   #11
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Dtc 507 High Idle
The PCM controls engine idle speed by adjusting the position of the idle air control (IAC) motor pintle. The IAC is a bi-directional motor driven by two coils. The PCM sends pulses (steps) to the IAC to extend or retract the IAC pintle into a passage in the throttle body to decrease or increase air flow. The commanded IAC position (displayed in counts) can be monitored on the scan tool. A lower number of counts indicates less commanded airflow (pintle extended). This method allows highly accurate control of idle speed and quick response to changes in engine load. If the PCM detects a condition where too high of an idle speed is present and the PCM is unable to adjust idle speed by decreasing the IAC counts, DTC P0507 will set indicating a problem with the idle control system.

Conditions for Setting the DTC
No VSS, TP sensor, EVAP system, EVAP solenoid, misfire, IAT sensor, MAP sensor, fuel trim, fuel injector, EGR pintle position, EGR flow, ECT sensor, CKP sensor, or MAF sensor DTCs set.
Engine Coolant Temperature is greater than 70C (158F).
The engine has been running for at least 5 seconds.
Vehicle Speed is less than 3 MPH.
Intake Air Temperature is greater than -20C (-4F).
The throttle is closed.
Engine Speed is more than 175 RPM higher than Desired Idle (positive idle speed error greater than 175 RPM).
The above conditions are present for longer than 20 seconds.

Action Taken When the DTC Sets
The PCM will illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the diagnostic test has been run and failed.
The PCM will store conditions which were present when the DTC set as Freeze Frame and Failure Records data.

Conditions for Clearing the MIL/DTC
The PCM will turn OFF the MIL during the third consecutive trip in which the diagnostic has been run and passed.
The History DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
The DTC can be cleared by using the scan tool.

Diagnostic Aids
Check for the following conditions:

Poor connection at the PCM or IAC motor Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection.
Damaged harness Inspect the wiring harness for damage.
Vacuum leak Check for a condition that causes a vacuum leak, such as disconnected or damaged hoses, leaks at EGR valve and EGR pipe to intake manifold, leaks at throttle body, malfunctioning or incorrectly installed PCV valve, leaks at intake manifold, etc.
Throttle body. Check for a sticking throttle plate. Also inspect the IAC passage for deposits or objects which will not allow the IAC pintle to fully extend.
Reviewing the Fail Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to be set occurs. This may assist in diagnosing the condition.
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