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Will a bad IAC valve cause overheating in less than a half hour of run time? 22re.

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No. The IAC valve controls the idle of the vehicle, and not the cooling. Most likely has a bad radiator and thermostat. See if running the heater on high heat and high fan brings the temps down. If it does, this is the problem. If not, possibly fan not turning like it should.

Posted on Jun 04, 2009


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2003 f150 with a 4.6 eng. trouble codes po174 po125 po171 p1131 po136 po156 p1151

All of the codes you are getting except for one are indicating a running lean condition. This is most likely due to a vacuum leak or the pintle on the egr valve is worn out allowing exhaust gases to pass through all the time. If you have access to a monitor check the iac duty cycle as well as the dpfe sensor. If the iac is reading less than forty percent you have a vacuum leak. As well if the dpfe is reading above 1.13 volts the egr valve is bypassing. The last code you have is being caused by a faulty thermostat.

Sep 28, 2014 | 2003 Ford F150 Regular Cab

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My car starts fine when engine is warm. I turn it off then try starting it again. then starts up and shuts back off. does it like 3 times in a row. then I wait a few minutes then it starts up when I push...

stalls, are complex
if the engine is good (compression at spec)
it this list.
1: lost electric power to EFI system or spark.
2: bad fuel.
3: bad spark.
4: bad fueling. (too much or too little.
5: EGR stuck open
6: ISC dead. or IAC dead. (idle air valves failing cold)

there are tests for each.
cold start failure only ! all else good, engine tuneup done?
1: ECT fibbing like oh'bummer. (signals water temps of alaska in Panama? "floods, and your right foot helps./..........
2: IAC (cold start fast idle air valve bad) same for right foot....
3: check engine light on running? is it?

ECT can cause gross over fueling.
the IAC dead will cause gross under AIR which in fact causes flooding (less air plus same fuel = flood)
bad fuel.

Oct 12, 2013 | 1999 Honda Accord

1 Answer

Blue smoke at low rpms on a 22re toyota

Blue smoke indicates burning oil in the cylinders. Could be worn piston rings, worn valve guides, or bad valve stem seals. An engine compression test may help find it, but a cylinder leak-down test is a more precise way to find where compression is being lost. If compression is good, you just may need to replace the old rubber valve stem seals. A shop could do it without having to remove the cylinder head, using an air compressor hooked up into each cylinder while the valve train is being worked on. The air is used to keep the valves from falling into the cylinder while the seals are replaced. About a 4 hour labor cost, so expensive, but a lot less than a cylinder head removal.

Jul 18, 2013 | Cars & Trucks

1 Answer

My ford taurus SE 1999 have 3 codes P1504, P1507 and P1131

DTC Description Possible Causes Diagnostic Aides P1504 - Idle Air Control (IAC) Circuit Malfunction This DTC is set when the PCM detects an electrical load failure on the IAC output circuit.
  • IAC circuit open
  • VPWR to IAC solenoid open
  • IAC circuit short to PWR
  • IAC circuit short to GND
  • Damaged IAC valve
  • Damaged PCM
  • The IAC solenoid resistance is from 6 to 13 ohms.
    • IAC valve stuck open
    • Vacuum leaks
    • Failed EVAP system
    • Damaged PCM
  • The IAC solenoid resistance is from 6 to 13 ohms.
P1507 - Idle Air Control (IAC) Underspeed Error This DTC is set when the PCM detects engine idle speed that is less than the desired rpm.
  • IAC circuit open
  • IAC circuit short to PWR
  • VPWR to IAC solenoid open
  • Air inlet is plugged
  • Damaged IAC solenoid
  • Damaged PCM
  • The IAC solenoid resistance is from 6 to 13 ohms
  • Disconnect IAC valve and look for no change in engine rpm as an indication of a stuck or damaged valve
P1131 - Lack of HO2S-11 Switch, Sensor Indicates Lean A HEGO sensor indicating lean at the end of a test is trying to correct for an over-rich condition. The test fails when the fuel control system no longer detects switching for a calibrated amount of time.
  • Electrical:
    • Short to VPWR in harness or HO2S
    • Water in harness connector
    • Open/Shorted HO2S circuit
    • Corrosion or poor mating terminals and wiring
    • Damaged HO2S
    • Damaged PCM
  • Fuel System:
    • Excessive fuel pressure
    • Leaking/contaminated fuel injectors
    • Leaking fuel pressure regulator
    • Low fuel pressure or running out of fuel
    • Vapor recovery system
  • Induction System:
    • Air leaks after the MAF
    • Vacuum Leaks
    • PCV system
    • Improperly seated engine oil dipstick
  • EGR System:
    • Leaking gasket
    • Stuck EGR valve
    • Leaking diaphragm or EVR
  • Base Engine:
    • Oil overfill
    • Cam timing
    • Cylinder compression
    • Exhaust leaks before or near the HO2S(s)
A fuel control HO2S PID switching across 0.45 volt from 0.2 to 0.9 volt indicates a normal switching HO2S.

Mar 16, 2011 | 1999 Ford Taurus

1 Answer

Motor reves up high when started can not keep it running because its reved up so high

First check to make sure the throttle return springs are closing the throttle. If that's good, the problem is likely a bad idle air control valve/motor. Take the valve out and check for obstructions in the port that could keep the valve from closing. Then, if you have an ohmmeter, you can run these checks on the valve:
    IAC location:
    Remove IAC, check for obstructions in passage, run electrical testsjturcotte_551.gif
    1. Disengage the IAC electrical connector.
    2. Using an ohmmeter, measure the resistance between IAC terminals A and B . Next measure the resistance between terminals C and D .
    3. Verify that the resistance between both sets of IAC terminals is 20-80 ohms. If the resistance is not as specified, the IAC may be faulty.
    4. Measure the resistance between IAC terminals B and C . Next measure the resistance between terminals A and D .
    5. Verify that the resistance between both sets of IAC terminals is infinite. If the resistance is not infinite, the IAC may be faulty.
    6. Also, with a small mirror, inspect IAC air inlet passage and pintle for debris. Clean as necessary, as this can cause IAC malfunction.

Dec 19, 2010 | 1997 Chevrolet Cavalier

1 Answer

When driving the 1997 Dodge Ram Truck wants to stall. You have to keep your foot on the gas at all times or it will stall.

you are probably having a problem with the IAC valve. idle air control valve. This device maintains the idle speed. It is probably gummed up with deposits. buy a can of spray carb cleaner and a new PCV valve( if it has never been replaced). remove the IAC valve (torx bits) and clean with an old toothbrush and carb cleaner, clean out the bore from which it came. Re-install. replace PCV valve and clean throttle bore and plate using tooth brush and towels. Go to to see pics of these parts. The IAC is near the thottle plate assembly. has a tutorial on how to replace these parts.

Other problems could be stuck EGR valve or bad IAC valve. but try the above fix first, less than $10.

Nov 21, 2010 | Dodge Ram 1500 Cars & Trucks

1 Answer

2005 F150 5.4 Cuts off when driving at constant speed and show "Engine Fail Safe Mode" on display. It will crank back up and run for several hundred miles before doing it again. P2112 Throttle Air...

unfortunately no ! Your best bet take it to the dealer . The P0420 always ends up being the catalytic converter ! P2104 isn't throttle air control . P2112 - Throttle Actuator Control (TAC) System - Stuck Closed. Description: This powertrain control module (PCM) fault status indicates the throttle plate is at a lower angle than commanded. Possible Causes:
  • Binding throttle body, stuck closed.
  • Damaged PCM.
Diagnostic Aids: Application Key On Engine Off Key On Engine Running Continuous Memory All GO to DV1
P2104 - Throttle Actuator Control (TAC) System - Forced Idle Description: The TAC system is in the failure mode effects management (FMEM) mode of forced idle. Possible Causes:
  • Open or short in multiple accelerator pedal position (APP) sensor circuits.
  • Damaged APP sensor.
  • Damaged powertrain control module (PCM).
Diagnostic Aids: This DTC is an informational DTC and can be set in combination with a number of other DTCs which are causing the FMEM. Diagnose other DTCs first. Application Key On Engine Off Key On Engine Running Continuous Memory All GO to QE1
P0506 - Idle Air Control (IAC) System RPM Lower Than Expected For Vehicles With Electronic Throttle Control (ETC) Description: This DTC is set when the powertrain control module (PCM) detects an engine idle speed that is less than the desired RPM. Possible Causes:
  • Air intake restriction.
  • Exhaust restriction.
  • Engine mechanical fault.
  • Damaged electronic throttle body (ETB).
  • Damaged PCM.
Diagnostic Aids: This DTC is informational only and it may be accompanied by other DTCs. Diagnose other DTCs first. If other DTCs are not present inspect the intake air system for air restrictions and damage. If no concerns are present, clear the DTC and retest. For All Others Description: This DTC is set when the powertrain control module (PCM) detects an engine idle speed that is less than the desired RPM. Possible Causes:
  • IAC circuit open.
  • Air inlet is plugged.
  • B+ or VPWR to IAC solenoid open.
  • Damaged or incorrect IAC valve.
  • IAC valve stuck closed.
  • VPWR to IAC solenoid open.
  • IAC circuit shorted to PWR.
Diagnostic Aids: Disconnect the IAC valve and look for little or no change in engine RPM as an indication of a stuck or damaged valve. Application Key On Engine Off Key On Engine Running Continuous Memory Vehicles With Electronic Throttle Control (ETC) Refer to the Description, Possible Causes and Diagnostic Aids for the DTC. All others GO to KE1

Jul 03, 2017 | 2005 Ford F-150

1 Answer

2002 Santa Fe 2.7 V6 (California Car) 260,000 + miles. Engine idle will increase to about 1500 RPM and drop back to normal without notice, at times difficult to start (must hold throttle about half open)...

I faulty Idle Air Control valve (IAC) can cause these specific symptoms. You could try diconnecting the IAC valve (usually near the throttle body) and regulating the idle yourself. If the fluctuations go away and you are able to hold a constant idle position with the gas pedal (if vehicle will start), the IAC is the problem.

Nov 14, 2009 | 2002 Hyundai Santa Fe

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