rough idle
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Joined: May 2009
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rough idle
have a 99 cavilier with 2.2 litre engine, got a P0507 code yesterday, changed the Iac valve, but car is still idling roughly. Noticed that as soon as car is started, the pintal on the iac valve opens up all the way allowing to much air. Is there another sensor that will control this valve.
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Joined: Jan 2008
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Here's some info that might prove helpfull. It pertains to the code you got. To me, it sounds like you may have a vacuum leak
DTC P0507 Idle Speed High
Circuit Description
The Powertrain Control Module (PCM) controls the air entering into the engine with an idle air control (IAC) valve. To increase the idle RPM, the PCM commands the pintle inside of the IAC valve away from the throttle body seat. This allows more air to bypass through the throttle blade. To decrease the RPM, the PCM commands the pintle towards the throttle body seat. This reduces the amount of air bypassing the throttle blade. A scan tool will read the IAC valve pintle position in counts. The higher the counts, the greater the airflow that bypasses the throttle blade.
Conditions for Running the DTC
Conditions for Setting the DTC
Action Taken When the DTC Sets
Conditions for Clearing the MIL/DTC
Diagnostic Aids
DTC P0507 Idle Speed High
Circuit Description
The Powertrain Control Module (PCM) controls the air entering into the engine with an idle air control (IAC) valve. To increase the idle RPM, the PCM commands the pintle inside of the IAC valve away from the throttle body seat. This allows more air to bypass through the throttle blade. To decrease the RPM, the PCM commands the pintle towards the throttle body seat. This reduces the amount of air bypassing the throttle blade. A scan tool will read the IAC valve pintle position in counts. The higher the counts, the greater the airflow that bypasses the throttle blade.
Conditions for Running the DTC
• DTCs P0105, P0107, P0108, P0112, P0113, P0117, P0118, P0122, P0123, P0125, P0131, P0132, P0133, P0134, P0200, P0335, P0341, P0342, P0440, P0442, P0446, P0480, P0502, P0503, P0601, P0602, P1133, and P1441are not set
• The BARO is more than 72 kPa.
• The engine coolant temperature (ECT) is more than 40°C (104°F).
• The engine has been running more than 20 seconds.
• The throttle position (TP) angle is less than 1 percent.
• The BARO is more than 72 kPa.
• The engine coolant temperature (ECT) is more than 40°C (104°F).
• The engine has been running more than 20 seconds.
• The throttle position (TP) angle is less than 1 percent.
Conditions for Setting the DTC
• The idle speed deviates above the desired RPM by more than 60 RPM for more than 5 seconds.
• The IAC valve reads less than 2 counts on the scan tool for more than 13 seconds.
• The IAC valve reads less than 2 counts on the scan tool for more than 13 seconds.
Action Taken When the DTC Sets
• The malfunction indicator lamp (MIL) will illuminate after two consecutive ignition cycles in which the diagnostic runs with the malfunction present.
• The PCM will record the operating conditions at the time that the diagnostic fails. This information will store in the Freeze Frame and Failure Records buffers.
• A history DTC stores.
• The coolant fan turns ON.
• The PCM will record the operating conditions at the time that the diagnostic fails. This information will store in the Freeze Frame and Failure Records buffers.
• A history DTC stores.
• The coolant fan turns ON.
Conditions for Clearing the MIL/DTC
• The MIL will turn OFF after three consecutive ignition cycles in which the diagnostic runs without a fault.
• A history DTC will clear after 40 consecutive warm-up cycles without a fault.
• The MIL/DTCs can be cleared by using the scan tool.
• A history DTC will clear after 40 consecutive warm-up cycles without a fault.
• The MIL/DTCs can be cleared by using the scan tool.
Diagnostic Aids
• Inspect the IAC valve electrical connection for proper mating.
• Inspect the wiring harness for damage.
• Inspect for a disconnected, cracked or cut vacuum hoses.
• Inspect the intake manifold and throttle body for leaks.
• Inspect the intake manifold for cracks.
• Inspect the wiring harness for damage.
• Inspect for a disconnected, cracked or cut vacuum hoses.
• Inspect the intake manifold and throttle body for leaks.
• Inspect the intake manifold for cracks.
Last edited by shawnvw; May 1, 2009 at 12:54 PM.
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Joined: Jan 2009
Posts: 338
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From: No. Md
Clean the original IAC valve and stick that back in to make sure the new one isn't fluke. Second. Next time it comes back, turn the vehicle off and see if the high idle goes away. If so that would indicate the TPS is bad. I would also recommend cleaning the throttle body. Remove it, don't just spray crap in there. That doesn't do anything. I would also check for a vacuum leak. Spray around anything vacuum related. Any lines, throttle body gasket, intake manifold gasket. Turn the car on and use brake clean. If the idle changes, where ever you are spraying is where the leak is.
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