Question about 1994 Chevrolet Caprice Classic

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On my 94 caprice the idle is messed up it was running at 1200 rpm i changed the mass air flow sensor and the iac motor and the pcv valve to get idle to 700 rpm now when i start the car it boggs down and running ruff the motor shakes alot any idea what it could be (fuel?)

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One of the sensors or actuators you changed is not electrically compatible with your module. it will look exactly the original but is different. Check for loose cables at the restof the sensor that could be moved when serviced the car

Posted on Oct 13, 2009

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1 Answer

Where is my pcv valve on my 2000 ford escort


Check for vacuum leaks. PCV has hose from top of valve cover and runs down underneath by exhaust to the valve. Just follow the hose. Possible bad idle air controller (IAC). You can also unplug the mass air flow sensor and see if it runs any better. (It will set a code but you can clear it)

May 17, 2015 | 2000 Ford Escort

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It starts but as soon as it's put into gear acts like it wants to go but quits.


Could be a few things. But here are the obvious. Check for a vacuum leak around the intake. When you put the car into drive it starts putting strain on the engine, a vacuum leak will give it too much oxygen and cause a fuel mixture issue / reading.
If nothing wrong there, you may have a bad throttle position sensor. When you put the car into drive and it starts putting strain on the engine it will pull the idle down then the sensor will adjust it automatically. Hope this helps.

Mar 18, 2015 | 2000 Chevrolet Blazer

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I recently purchased a 2002 mitisbushi lancer and the idle was going up and down. When i turned air conditioner on the idle went down, when i turned it off the idle went up. Now with that being said i put...


Disconnecting the battery will not delete stored fault history. It must be done with a CRT (Snap- On 3000) or equivalent. The idle condition you have now should be the opposite. 1200 RPM with air on 900 with air off. This vehicle is at an age where several components are probably out of range. I would try changing the cheapest parts first. 1 Fuel filter 2 Air filter 3 Thermostat For Coolant) 4 All coolant temp sensors (They can affect idle) 5 MAP sensor(manifold absolute pressure sensor) 6 Idle air motor. Sometimes the idle air motor can be cleaned . Check pintle and seat for carbon build up, clean with a valve guide brush. Pintle not seating will cause idle problems

May 19, 2017 | Cars & Trucks

2 Answers

Stalls while in drive with foot on brake , changed MAP Sensor, Crank Shaft Sensor , Distributor, Fuel Pump, Fuel Filter , have ran out of ideas


I would check the IAC motor or idle air control motor, heres a little info.about the part.Stratus Sedan, 1999-2005 Idle Air Control Motor

Print


Description & Operation

Not for Dodge Stratus Sedan
The idle air control motor (IAC) attaches to the throttle body. It is an electric stepper motor. The PCM adjusts engine idle speed through the idle air control motor to compensate for engine load, coolant temperature or barometric pressure changes. The throttle body has an air bypass passage that provides air for the engine during closed throttle idle. The idle air control motor pintle protrudes into the air bypass passage and regulates airflow through it.
The PCM adjusts engine idle speed by moving the IAC motor pintle in and out of the bypass passage. The adjustments are based on inputs the PCM receives. The inputs are from the throttle position sensor, crankshaft position sensor, coolant temperature sensor, MAP sensor, vehicle speed sensor and various switch operations (brake, park/neutral, air conditioning).

0996b43f8020234f.jpg enlarge_icon.gifenlarge_tooltip.gif

Fig.

Not for Dodge Stratus Sedan
When engine rpm is above idle speed, the IAC is used for the following functions:


Off-idle dashpot Deceleration air flow control A/C compressor load control (also opens the passage slightly before the compressor is engaged so that the engine rpm does not dip down when the compressor engages)
The idle air control motor (IAC) attaches to the throttle body. It is an electric stepper motor. The PCM adjusts engine idle speed through the idle air control motor to compensate for engine load, coolant temperature or barometric pressure changes. The throttle body has an air bypass passage that provides air for the engine during closed throttle idle. The idle air control motor pintle protrudes into the air bypass passage and regulates airflow through it.
The PCM adjusts engine idle speed by moving the IAC motor pintle in and out of the bypass passage. The adjustments are based on inputs the PCM receives. The inputs are from the throttle position sensor, crankshaft position sensor, coolant temperature sensor, MAP sensor, vehicle speed sensor and various switch operations (brake, park/neutral, air conditioning).

21180_cdia_g257.jpg enlarge_icon.gifenlarge_tooltip.gif

Fig.

When engine rpm is above idle speed, the IAC is used for the following functions:


Off-idle dashpot Deceleration air flow control A/C compressor load control (also opens the passage slightly before the compressor is engaged so that the engine rpm does not dip down when the compressor engages)
Target Idle
Target idle is determined by the following inputs:


Gear position ECT Sensor Battery voltage Ambient/Battery Temperature Sensor VSS TPS MAP Sensor
Target idle is determined by the following inputs:


Gear position ECT Sensor Battery voltage Ambient/Battery Temperature Sensor VSS TPS MAP Sensor


Removal & Installation

  1. Disconnect the negative battery cable.
  2. Disconnect the IAC electrical connector.
  3. Remove the IAC mounting screws.
  4. Remove the IAC.

To Install:
  1. Install the IAC to the throttle body.
  2. Tighten mounting screws to 5.1 Nm (45 inch lbs.) torque.
  3. Attach electrical connector to the IAC.
  4. Connect the negative battery cable.

    0996b43f80202350.jpg enlarge_icon.gifenlarge_tooltip.gif

    Fig.


  1. Disconnect the negative battery cable.
  2. Disconnect the IAC electrical connector.
  3. Remove the IAC mounting screws.
  4. Remove the IAC.

To Install:
  1. Install the IAC to the throttle body.
  2. Tighten mounting screws to 5.1 Nm (45 inch lbs.) torque.
  3. Attach electrical connector to the IAC.
  4. Connect the negative battery cable.

May 11, 2012 | 2000 Chrysler Cirrus

1 Answer

Specify were the pcv valve is located on 95 mustang v8?


Look on top of the block at back by firewall for PCV. Other things you may want to check/clean are idle air control valve on side of throttle body, as well as mass air flow sensor in intake air assembly. Clean IAC with throttle body spray cleaner and port it is removed from well, and try. Use tuner cleaner or electrical cleaner on MAF sensor . Sometimes just cleaning will cure it.

Apr 09, 2012 | 1995 Ford Mustang GT

1 Answer

Cleaned throttle body on chevy 03 1500. Now has high idle about 1200 rpm and surges up and down?


Hi.

Check the following in order:

IAC valve wiring, connectors and vacuum hoses.
Look for vacuum hoses that are not connected in general.
EGR valve wiring, connectors and vacuum hoses.
PCV system.
Wiring to the two sensors in the air intake.
Check position of the air intake for leaks. Tighten its screws.
Check wiring in general.
Do a code scanning if you have not found anything so far, check wiring of ECM and O2 sensors.

If the car idles up and down there may be an air leak from air intake or IAC, EGR, there may be a vaccuum leak or PCV system may be malfunctioning. Those are the things to check first and with more attention.

Regards.

Ginko

Sep 19, 2011 | 2003 Chevrolet Silverado 1500

1 Answer

1995 Blazer with Vortec V-6 was running fine until 4 days ago. Check engine light came on, now it starts and idles fine, but when placed in gear, idle drops, engine bogs and dies. I am targeting the Idle...


IAC idler air control valve bumps up the RPM and doesnot let the engine to die, how ever if its not the IAC then Ide be looking at the TEMP sensor which migh have a fair line crack or may be the MAF mass air flow sensor might be bad, seems like the engine is not geting air, check the air filter first.

Feb 28, 2011 | 1995 Chevrolet Blazer

1 Answer

Will not idle, will run if you push on the gas and hold it. No engine light indicator


you need to clean your idle air control valve ( or replace it) Spray carb cleaner does a nice job of cleaning it.

This tutorial is from autozone.com


OPERATION



The Idle Air Control (IAC) is a bi-directional motor driven by two coils. The purpose of the IAC valve is to control engine idle speed, while preventing stalls due to changes in the engine load. The IAC valve, mounted in the throttle body, controls bypass air around the throttle plate. The PCM controls engine idle speed by adjusting the position of the IAC motor pintle. The PCM pulses current to the IAC coils in small steps (counts) to extend the pintle into a passage in the throttle body to decrease air flow. The PCM reverses the current pulses to retract the pintle, increasing air flow. This method allows highly accurate control of idle speed and quick response to changes in engine load. If RPM is too low, the PCM will retract the IAC pintle, resulting in more air being bypassed around the throttle plate to increase RPM. If the RPM is too high, the PCM will extend the IAC pintle, allowing less air to be bypassed around the throttle plate, decreasing RPM.



0900c15280217cd2.jpg enlarge_icon.gifenlarge_tooltip.gif

Fig. Typical Idle Air Control (IAC) valve components
During idle, the proper position of the of the IAC pintle is calculated by the PCM based on the battery voltage, coolant temperature, engine load and engine RPM. If the RPM drops below a specified value, and the throttle plate is closed (TP sensor voltage is between 0.20-0.74), the PCM senses a near stall condition. The PCM will then calculate a new IAC pintle position to prevent stalls.
If the IAC valve is disconnected and reconnected with the engine running, the idle RPM will be wrong. In this case, the IAC has to be reset. The IAC resets when the ignition switch is cycled ON and then OFF . When servicing the IAC, it should be disconnected or connected with the ignition switch OFF in order to keep from having to reset the IAC valve.
The position of the IAC pintle affects engine start up and the idle characteristics of the vehicle. If the IAC pintle is fully open, too much air will be allowed into the manifold. This results in high idle speed, along with possible hard starting and a lean air/fuel ratio. A Diagnostic Trouble Code (DTC) may set. If the IAC pintle is stuck closed, too little air will be allowed in the manifold. This results in a low idle speed, along with hard starting and a rich air/fuel ratio. Again, a Diagnostic Trouble Code (DTC) may set. If the IAC pintle is stuck part way open, the idle may be high or low and will not respond to changes in engine load.


TESTING



As with most all engine control sensors used in your vehicle, a thorough and proper test can only be performed by a qualified technician using a scan tool to read the data stream from the PCM. There are a few items a non-professional should check before taking the vehicle to a qualified technician for diagnosis and repair.



Check for a poor connection at the PCM or IAC motor. Inspect the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals and poor terminal-to-wire connection. Inspect for a damaged wiring harness, especially if heavy work has recently been performed (intake manifold removal, engine removal, etc.) where the throttle body has been disturbed. Inspect for a restricted air intake system. Check for a possible collapsed air intake duct, restricted air filter element or foreign objects blocking the air intake system. Inspect the throttle body. Check for objects blocking the IAC passage or throttle bore. Excessive deposits, especially on high-mileage engines, can build up in the IAC passage and on the IAC pintle. Excessive deposits can also build up on the throttle plate, so check for a sticking throttle plate. Check for vacuum leaks such as disconnected hoses, leaks at the EGR valve and EGR pipe to the intake manifold, leaks at the throttle body, faulty or incorrectly installed PCV valve, leaks at the intake manifold brake booster hose connection, etc.



REMOVAL & INSTALLATION



  1. Disconnect the negative battery cable.
  2. Detach the electrical connector from the IAC valve.
  3. Remove the 2 attaching screws and remove the IAC valve from the engine. Remove the O-ring from the housing.

To install:



0900c15280217cd3.jpg enlarge_icon.gifenlarge_tooltip.gif

Fig. The Idle Air Control (IAC) valve is mounted on the throttle body-3.8L (VIN K) engine shown, others similar


NOTE Before installing a new IAC valve, measure the distance that the valve is extended. The measurement should be made from the motor housing to the end of the valve cone (pintle). The distance should be no greater than 1 1 / 8 inch (28mm). If the pintle is extended too far, adjustment is required, otherwise damage may occur when the IAC valve is installed. Adjust the IAC valve by compressing the pintle to achieve the correct length.


  1. Use a new O-ring, install the IAC valve and tighten the retaining screws to 18 inch lbs. (2 Nm).
  2. Attach the electrical connector.
  3. Connect the negative battery cable.
  4. The PCM will reset the IAC valve the next time the ignition switch is turned ON and then OFF .
  5. Start the engine and allow to warm to operating temperature to check idle quality.

Oct 13, 2010 | 2000 Pontiac Grand Prix

2 Answers

1992 F-150 Idle is to fast


check you throttle positioning sensor, also check your mass air flow sensor, by unplugging while your motor is running if idle returns to normal that may be the prob. hope i could help

Mar 24, 2009 | 1992 Ford F150 SuperCab

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