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Mark, IAC (Idle Air Control Valve), If engine is idling too fast, problem may not be the idle speed control system, but an engine vacuum leak. Check for vacuum leaks first to rule this possibility out. Also on your Toyota low coolant, air in the cooling system can cause the valve not to operate properly as I believe coolant has to run through valve for it to operate correctly. Fill/bleed air from cooling system. Check the attached links,instruction and guides, Good luck
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It seems like the problem lies with the engine management system, rather than the brakes. Given that you've already replaced the MAF, MAP, and TPS sensors, here are some other things to check:
1. Vacuum leaks: Inspect all vacuum lines for cracks or damage that may be causing a leak. A vacuum leak can cause erratic idling, poor acceleration, and stalling.
2. Idle air control (IAC) valve: The IAC valve controls the engine's idle speed. A malfunctioning IAC valve can cause the engine to stall during idling. Try cleaning the IAC valve with carburetor cleaner and see if the issue is resolved.
It's called IAC - idle air control valve > Did the RPM'S stay at 2000 or drop back down ? The PCM engine computer controls IAC valve according to engine load . Put it in gear , turn on electrical loads , headlamps , A/C etc... an the RPM raise's up so engine will not stall . More then likely the throttle plate needs to be cleaned , they get gummed up an stick at higher idle . Quick Tip Throttle Cleaning EricTheCarGuy If the IAC valve were gummed up the idle would be low or erratic . On some engines a vacuum leak will cause high idle . Videos on youtube checking for vacuum leaks .
Possible causes
- Faulty Idle Air Control (IAC) valve
- Idle Air Control (IAC) valve harness is open or shorted
- Idle Air Control (IAC) valve circuit poor electrical connection What does this mean? Tech notes
The P1507 code means that the engine idle is out of factory specification. Sometimes the Idle Air Control (IAC) may have carbon built up. Disconnect the car battery, remove the valve, clean, re-install valve, and drive the vehicle for about 5 minutes with the headlights and A/C ON to get the idle relearned.
If the problem persist, the IAC valve may need to be replaced.
I don't see this as related to the console. This issue is usually caused by the idle air control valve. The valve may be bad or possibly the wiring. If it's the wiring, normally the computer will turn on the engine light.
You can check the valve operation using a common obd2 scanner in data mode.
Here is more info from autozone.com:
Engine idle speeds are controlled by the PCM through the Idle Air Control (IAC) valve mounted on the throttle body. The PCM sends voltage pulses to the IAC motor windings causing the IAC motor shaft and pintle to move in or out a given distance (number of steps) for each pulse (called counts). The movement of the pintle controls the airflow around the throttle plate, which in turn, controls engine idle speed. IAC valve pintle position counts can be observed using a scan tool. Zero counts correspond to a fully closed passage, while 140 counts or more corresponds to full flow.
Idle speed can be categorized in 2 ways: actual (controlled) idle speed and minimum idle speed. Controlled idle speed is obtained by the PCM positioning the IAC valve pintle. Resulting idle speed is determined by total air flow (IAC/passage + PCV + throttle valve + calibrated vacuum leaks). Controlled idle speed is specified at normal operating conditions, which consists of engine coolant at normal operating temperature, air conditioning compressor OFF, manual transaxle in neutral or automatic transaxle in D .
Minimum idle air speed is set at the factory with a stop screw. This setting allows a certain amount of air to bypass the throttle valves regardless of IAC valve pintle positioning. A combination of this air flow and IAC pintle positioning allows the PCM to control engine idle speed. During normal engine idle operation, the IAC valve pintle is positioned a calibrated number of steps (counts) from the seat. No adjustment is required during routine maintenance. Tampering with the minimum idle speed adjustment may result in premature failure of the IAC valve or improperly controlled engine idle operation.
TESTING
The IAC can be monitored with an appropriate and Data-stream capable scan tool
OPERATION
The Idle Air Control (IAC) valve controls the engine idle speed and dashpot functions. The valve is located on the throttle body on. This valve allows air to bypass the throttle plate. The amount of air is determined by the Powertrain Control Module (PCM) and controlled by a duty cycle signal.
Fig. 1: Cleanable IAC valve — 5.0L engine version shown, others similar
Fig. 2: Non-cleanable IAC valve — 5.0L engine version shown, others similar
TESTING OBD-I System
Make sure the ignition key is OFF.
Disconnect the air control valve.
Use an ohmmeter to measure the resistance between the terminals of the valve solenoid.
NOTE: Due to the diode in the solenoid, place the ohmmeter positive lead on the VPWR pin and the negative lead on the ISC pin.
If the resistance is not 7–13 ohms, replace the air control valve.
--- REMOVAL & INSTALLATION
Fig. 1: Idle air control valve mounting — 4.9L engine version shown, others similar
Disconnect the negative battery cable.
Disconnect the engine wiring to the IAC sensor.
Remove the two retaining screws for the valve.
Remove the IAC valve and discard of the old gasket.
Fig. 2: Disengage the idle air control solenoid electrical connection
Fig. 3: Loosen the idle control solenoid retaining screws
Fig. 4: Remove the idle air control solenoid from the throttle body
To install:
Clean the area of old gasket material.
Using a new gasket, attach the IAC valve to the engine. Tighten the retaining screws to 71–102 inch lbs. (8–12 Nm).
Check the fuel filter on car for a restriction. Check the air filter for a restriction(dirty). also check the IAC valve (idle/air/control) located on the side of the throttle body. To check the iac valve, start the engine and disconnect the electrical plug from the iac. Listen for a change in the idle of the engine. then reconnect the plug to the iac valve and turn on the a/c and listen for the engine idle speed to change. If not then replace the iac valve. Hope this will help you.
Section 03-14: Engine Controls, Electronic
1996 Taurus, Sable Workshop Manual
REMOVAL AND INSTALLATION
Idle Air Control (IAC) Valve
Removal
Disconnect battery ground cable (14301). Refer to Section 14-01 .
Disconnect the engine control sensor wiring (12A581) from the idle air control valve (IAC valve) (9F715) at the idle air control valve electrical connector.
Remove the two idle air control valve retaining bolts.
Remove the idle air control valve and idle air control valve gasket.
Installation
NOTE: If scraping is necessary, be careful not to damage idle air control valve gasket surfaces, or drop material into intake manifold (9424) or throttle body (9E926) (depending upon application).
Clean idle air control valve gasket mating surfaces.
To install idle air control valve, reverse Removal procedure.
Tighten the idle air control valve retaining bolts to 8-12 Nm (71-106 lb-in).
you need to clean or replace your idle air control valve(IAC). The IAC allows your engine to idle smoothly by opening and closing a valve that allows air flow to the engine that is monitored by the computer. The IAC get dirty causing it to stick and move slower than it should which causes the up and down idle
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