Question about 2000 Pontiac Grand Prix

1 Answer

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

Posted by on

1 Answer

  • Level 3:

    An expert who has achieved level 3 by getting 1000 points

    All-Star:

    An expert that got 10 achievements.

    MVP:

    An expert that got 5 achievements.

    President:

    An expert whose answer got voted for 500 times.

  • Master
  • 1,565 Answers

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.



Will not idle, will run if you push on the gas and - 0900c15280217cd2.jpg enlWill not idle, will run if you push on the gas and - enlarge_tooltip.gifs=enlarge_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 fromWill not idle, will run if you push on the gas and - 0900c15280217cd3.jpg

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.

Posted on Oct 13, 2010

Testimonial: "I liked the quick response but do not know yet if the soultion will work. "

  • cheap repair Oct 13, 2010

    click on red X above to view pictures

×

1 Suggested Answer

6ya6ya
  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

Hi,
a 6ya expert can help you resolve that issue over the phone in a minute or two.
best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.
the service is completely free and covers almost anything you can think of (from cars to computers, handyman, and even drones).
click here to download the app (for users in the US for now) and get all the help you need.
goodluck!

Posted on Jan 02, 2017

Add Your Answer

Uploading: 0%

my-video-file.mp4

Complete. Click "Add" to insert your video. Add

×

Loading...
Loading...

Related Questions:

2 Answers

Why do i have to hold the petal to floor to get truck to start?


Could be a dirty egr valve exhaust gas recerlater. I had a problem where my car wouldn't start or stay running unless I had gas pedal mashed to floor and it was that problem

Mar 31, 2015 | Cars & Trucks

3 Answers

Stalling at low idle


I don't know this specific car. But, if it has one, check your Idle Air Valve. This can cause the engine to stall. If you can hold the gas pedal and the engine will continue to run until you let off the gas, it is likely the IAV. It will not necessarily cause the engine to run rough. That could be a number of things like spark plugs, wires or dirty injectors. It could also be a compression problem. Is the check engine light on?

Mar 04, 2014 | 1995 Dodge Intrepid

1 Answer

Truck wont idle, I have to keep gas pedal push in to keep truck running Engine light is on.


could be a throttle position sensor mass air flow or linkage on the throttle body or the throttle body itself

Jul 04, 2012 | Dodge Cars & Trucks

1 Answer

Hi guys...my yaris is running rich, has poor gas mileage (360km on a full tank). and very slow and choppy idle (idles like a really old car) these are the things i have done so far : change air and fu


Do the following:
1. Clean the throttle body from inside.
2. Adjust the spark plugs gap to 1.00 mm.
3. Check fuel pump pressure. (44 Psi - 49 psi)
4. Remove the negative battery terminal for 5 minutes.
5. Connect the battery terminal.
6. Check the engine oil level and coolant level.
NOTE: Before starting the engine shut off all lights and loads for example room light, blower, radio, parking light etc.
7. Start the engine and hold the throttle at 3000 rpm till radiator fan comes on.
8. After the fan comes on release the throttle pedal and let it idle for 10 minutes.

May 08, 2012 | 2005 Toyota Yaris 1.3

1 Answer

Engine will not idle slow.runs to fast bangs putting in gear.V/6 auto


you may have a vacume leak that is causing the engine to run faster than it should indicating that the car needs more fuel as the vacume leak acts like the throttle is open more than it really is,it could also be a bad tps sensor causing this showing the ecm that the gas pedal is pushed and needs more fuel.the throttle cable may not be going all the way to its rest position or something could be holding the throttle plate open.

Aug 10, 2011 | 1985 Ford Ranger

1 Answer

2007 toyota corolla stop accelerating, pushing gas


throttle position sensor needs to be changed

Jul 10, 2009 | 2005 Toyota Corolla

2 Answers

JUST DONT WANT TO RUN


Check the fuel pump.

Jan 09, 2009 | 1991 GMC S-15 Jimmy

1 Answer

Engine cuts out, console lights up


It sounds like your fuel filter is clogged. Try changing it.

Aug 18, 2008 | 1999 Chevrolet S-10 Pickup

Not finding what you are looking for?
2000 Pontiac Grand Prix Logo

1,318 people viewed this question

Ask a Question

Usually answered in minutes!

Top Pontiac Experts

yadayada
yadayada

Level 3 Expert

75744 Answers

Colin Stickland
Colin Stickland

Level 3 Expert

22114 Answers

Jeff Turcotte
Jeff Turcotte

Level 3 Expert

8123 Answers

Are you a Pontiac Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides

Loading...