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2004 chevy 2500 4.8 liter express work van, idle very low, replaced throttle body with IAC valve, disconnected battery for a couple of hours to reset computer , still low idle .

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6 Suggested Answers

6ya6ya
  • 2 Answers

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Posted on Jan 02, 2017

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emissionwiz
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SOURCE: PCV valve? IAC valve? Sparkplug wire? Throttle body? Vacuum hose?

the most common causes are plug wire, plug, vacuum leak at intake, fuel injector failure and last no/low cylinder compressio.

Posted on May 22, 2009

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csmock132
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SOURCE: 1989 GMC 2500 5.7L - engine surges and stalls at idle. Loses power at cruising speed.

Wow you have replaced a lot of stuff. Lets go back to the Fuel pump. When you replaced it did you replace the hose between the pump and the sending unit. These are common for splitting. Have you hooked up a fuel pressure gauge to check what pressure you have? It should be real close to 13 psi and should raise to at least 18 or 19 when you pinch off the return line.

Posted on Jun 02, 2009

  • 150 Answers

SOURCE: idle at 1500 to 2000 rpm

Most likely the throttle body gasket (between the throttle body and the intake manifold) is leaking.

Posted on Feb 12, 2009

  • 147 Answers

SOURCE: codes 171 and 174 2001 ford winstar

dont take soo much in consideration after you have make all this things, some time is on only for any wire faulty, or a shrt electrical arc in any place in wire system. ask auto tap mechsnics for this maybe they have similar case before.

Posted on Apr 06, 2009

  • 22 Answers

SOURCE: 1993 Toyota Camry IAC cleaning

1) remove the black intake hose from the throttle body
2) get a can of throttle body/intake cleaner
3) be VERY careful if you decide to use the straw included with the can of cleaner, it can detach and go inside of your intake manifold.
4) spray inside and use a rag to remove junk from throttle plate(front and back side), hold the straw on the cleaner can and spray into the hole just ahead of the throttle plate, let soak for 10 minutes or so
5) reattach intake hose and start engine - you may get black smoke/rough idle for a minute as junk exits the engine

Posted on Jul 22, 2009

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3 Answers

Where is the location of the idle air control valve in a 2004 chevy malibu?


If there are no cables coming off throttle body to control throttle there is no Idle Air Control valve. the idle is controlled electronically by the computer. If car is idling rough you can clean throttle body to correct this problem. If you do have cables to control throttle the IAC valve is located right next to throttle body attached to it. Hope this helps

Aug 03, 2014 | 2004 Chevrolet Malibu

1 Answer

03 Chev express 2500 wont stay running at an Idle, code reader says IAC valve but this engine dosnt have the IAC valve on it any Ideas


Hi there,

Your engine does indeed have an Idle Air Control (IAC) Valve.

It is a sensor bolted to your throttle body - look for an electrical connector.

A malfunctioning IAC can cause improper idle of your engine.

Nov 08, 2011 | Cars & Trucks

3 Answers

2003chevy pu dies at stop lights, low idle whats wrong?


yea id definately try cleaning ur throttle body 1st. My 03 1500hd had the exact same bad idle after my battery went bad it would die at lights unless i kept foot on gas i cleaned throttle body runs perfect now took 30min cost 8$ for cleaner at autozone and theres how to videos on you tube

Aug 13, 2011 | 2003 Chevrolet Silverado 1500

1 Answer

Have a 1996 Mitsubishi Galant and need intstuctions on how to replace the Idle Air Control Valve


You'll have to remove the throttle body to replace the idle air control (IAC) valve. First, disconnect the negative ground cable from the battery. Then remove the vacuum line and air duct intake. Then disconnect the IAC and throttle position sensor (TPS) electrical connections. Remove the coolant hoses that are connected to the IAC. Disconnect the throttle cable from the throttle body. Now, remove the 4 bolts that hold the throttle body to the manifold and remove. Be careful with the gasket located between the throttle body and manifold and replace it in the same position. On your clean work surface, turn the throttle body over and remove the 4 phillips head screws holding the IAC to the throttle body. Clean the parts with a dry cloth but do not use solvents on the IAC or TPS. That's it!

Dec 16, 2010 | 1998 Mitsubishi Galant

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

1 Answer

2006 chevy express 2500 van with 4.8L idles really low, when you floor it it bogs down, after you let off the gas it dies, replaced the fuel pump already


Clean the throttle body with throttle body cleaner and make sure the air filter is not dirty or plugged.Also clean the mas air flow sensor with mass air flow sensor cleaner.Give this a try and let me know if it took care of your problems.Hope this helps.Good luck.

Sep 05, 2010 | 2006 Chevrolet Express

1 Answer

I need to adjust my idle on a 1991 chevy s-10 carb


this should have a throttle body, not a carb. You can tell easilly by looking at it. You will have injectors on it and two sensors. One is a throttle position sensor and the other is an idle air control valve. make sure the throttle body is not coked around the throttle plate. Clean if nessasary which will allow more air to pass which will tell the computer to add more fuel. Also remove the IAC and clean it. If its coked it also will restrict the air at idle. Disconnect the battery so the IAC wil reset itslf or it may take a little driving after you clean them to reset. If this doesn't help you may need new injectors because they may be clogged or you may need a new IAC valve.

May 05, 2010 | 1991 Chevrolet S-10

1 Answer

3.2 liter yamaha engine manual IAC valve How do I replace the IAC valve on this engine? Steps? I just bought a new one and I need to get it replaced. FORD 1994 Taurus SHO 3.2 liter engine YAMAHA


may just need cleaning with carb cleaner.

here is 1996, oldest I have:

Section 03-14: Engine Controls, Electronic 1996 Taurus, Sable Workshop Manual
REMOVAL AND INSTALLATION Idle Air Control (IAC) Valve Removal
  1. Disconnect battery ground cable (14301). Refer to Section 14-01 .
  1. Disconnect the engine control sensor wiring (12A581) from the idle air control valve (IAC valve) (9F715) at the idle air control valve electrical connector.
  1. Remove the two idle air control valve retaining bolts.
  1. Remove the idle air control valve and idle air control valve gasket.
Installation
  1. 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.
  1. To install idle air control valve, reverse Removal procedure.
  1. Tighten the idle air control valve retaining bolts to 8-12 Nm (71-106 lb-in).
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Jan 14, 2010 | 1994 Ford Taurus

1 Answer

Throttle body removed and replaced


I'm not a chevy guy, but I think you need to reset the throttle position sensor (TPS) once it's disconnected.

For idle, the throttle plate is almost closed with just a little air getting through. For more air, an IAC idle air control valve lets more air in to maintain an ilde speed. The TPS tells the engine computer when the throttle plate is closed and then the computer tells the IAC to let more or less air in to maintain idle.

So, as long as you reconnected all the connectors you took off, I'm guessing you just need to make some readjustments. Calling your Chevy dealer service department, they can tell you if that's true.

Mar 03, 2009 | 2002 Oldsmobile Silhouette

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