idle problem

It is called "hunting" idle, caused by a bad or clogged IAC (idle air control valve) or a vacuum leak, which prevents the IAC from finding the correct idle speed.

1999-2005 Pontiac Grand Am has a screw to adjust idle speed. It is located on bottom side of the throttle body, and easiest to adjust if the throttle body is taken off. Has hex head, tighten to increase idle and loosen to reduce idle speed. I feel turning around 1.25 is good adjustment to test.

Hi,
There are a couple things going on with my Grand Am. Its a 2000 with about 69,000 automatic 2.4

First, every once and a while when i put the cruise control on it will automatically shut off and wont stay at a constant speed after about a mile of driving..

second, sometimes when im driving the engine revs up and down, I notice the RPM needle bounce up and down aswell

[quote:1d0126c058="Moonpie"]Hi,
There are a couple things going on with my Grand Am. Its a 2000 with about 69,000 automatic 2.4

First, every once and a while when i put the cruise control on it will automatically shut off and wont stay at a constant speed after about a mile of driving..

second, sometimes when im driving the engine revs up and down, I notice the RPM needle bounce up and down aswell[/quote:1d0126c058]

check brake switch and fuses
u need to have the ECM scanned for code
and the BCM also

i have a 1999 pontiac grand am se 2.4l 4c engine it has about 210000miles on it, a few days when i am driving between 10 and 40mph when i take my foot of the gas the RPMs will jump back and forth from 600rpms to 1300rpms and when i am in idle the engine shakes (idle speed is around 600to 700), i have changed all the sensors on the throttle body(MAP,IAC,Throttle Position Sensor ) Please Help.

Did you check sensor circuits, before you replaced anything? Did you take the throttle-body off and give it a good cleaning? You may have a vacuum leak somewhere? I've seen vacuum leaks and/or misfiring cylinders cause a lousy idle.

Are there any codes? Some of the national brand autostores will check codes for free.

[quote:1394526a46="jdl123"]Did you check sensor circuits, before you replaced anything? Did you take the throttle-body off and give it a good cleaning? You may have a vacuum leak somewhere? I've seen vacuum leaks and/or misfiring cylinders cause a lousy idle.

Are there any codes? Some of the national brand autostores will check codes for free.[/quote:1394526a46]


it has error code 507, all the sensor circuits are fine.

could this be a leak in the power stearing?

I have the same car as you do and my car use to shake when I was a drive thrus, or at red lights and it ended up being a simple vacuum leak. It would even shut off sometimes! SCARY! I got it fixed like 3 years ago and have had no problems! Hope this helps!

[quote:113ede3018="troy0007"][quote:113ede3018="jdl123"]Did you check sensor circuits, before you replaced anything? Did you take the throttle-body off and give it a good cleaning? You may have a vacuum leak somewhere? I've seen vacuum leaks and/or misfiring cylinders cause a lousy idle.

Are there any codes? Some of the national brand autostores will check codes for free.[/quote:113ede3018]


it has error code 507, all the sensor circuits are fine.

could this be a leak in the power stearing?[/quote:113ede3018]

Hello, the p0507 shows to be the idle-air system.

1999 Pontiac Grand Am 6 cyl Front Wheel Drive Automatic 95K miles

I have a 1999 Pontiac Grand Am GT, V6, with 95k miles. Sometimes at idle, the engine starts to sound and feel like it is "surging". The RPMs are staying steady. This usually happens when it is first started but it is starting to happen at redlights too. Any ideas?

You may be getting some minor EGR flow at idle, not enough to stall, but to change engine "tone".

Another possibility is the coil packs and plugs. GM had some trouble with 99's equipped with 3400 going through the coils and wires at 35k or so.

Also clean the IAC and pintle.

My car is idling at 3,000 RPMs. It also idles rough. When I drive, without pushing the case peddle, the car accelerates to 40 mph. At all driving times, the car will continue to accelerate until I hit the breaks, at which point it will begin accelerating again.

My car's service engine soon light is on. Do you have any idea of what type of problem I am experiencing?Even though my car has low miles, it is probably worth 2K at best, due to a recent accident causing a lot of body damage. Is my car even worth the cost of diagnosing and fixing the potential problem?

Thank you.

[quote:093ef1765d="ddraskovich"]Engine Mechanical problem
1999 Pontiac Grand Am 6 cyl Front Wheel Drive Automatic 78000 miles

My car is idling at 3,000 RPMs. It also idles rough. When I drive, without pushing the case peddle, the car accelerates to 40 mph. At all driving times, the car will continue to accelerate until I hit the breaks, at which point it will begin accelerating again.

My car's service engine soon light is on. Do you have any idea of what type of problem I am experiencing?Even though my car has low miles, it is probably worth 2K at best, due to a recent accident causing a lot of body damage. Is my car even worth the cost of diagnosing and fixing the potential problem?

Thank you.[/quote:093ef1765d]

Hello,

First thing I would do is go by your local auto zone and have them pull codes for you they will do it for free.

Post codes here in forum....

Also, it could be any number off things....

When was your last tune up?

Could be the IAC (Idle Air Control Valve), TPS (Throttle Position Sensor). So having codes pulled would greatly and quickly find problem.

I have a 1993 Pontiac Grand Am, When you start it in the morning it starts right up and idles good. After it worms up it starts to idle up and then down to almost dying and then idles back up and then back down, after two or three times it finally goes back to normal idle and then after about 1 or 2 min it does it again. when you shut it off and let it sit for 15 to 30 min and you then try to start it back up it crank and cranks and then finally starts and it smells like gas really bad.It has now started to miss as you are going down the road. I replaced the ACM (Air control module) but it made no difference. While it is running i can unplug the Mass Air Flow Sensor and it runs bad and then when i plug it back in it settles it down. So I think it is ok. There is a sensor right under the MAS that when i unplug it nothing happens but I do not know what it is. Can any one help with my problem.

can you get a fuel pressure guage and attatch it to the rail. this will let us know if its fuel or ignition related.

and the sensor that your talking about is the IAT sensor. intake air temp. unplugging it will cause no immediate effects

I have been struggling with a "service engine" light that comes on after a minute or two of idle with a warm engine, causing surging when leaving idle at low throttle. Shutting down the engine "reboots" the control, returning the car to normal operation until the next stoplight. Scope says something indefinite about the idle control motor, which has been replaced. What provides control input to the motor? Any ideas?

If you have a vacuum leak it can cause Idle control codes to appear, since the idle motor cant make the engine do what it wants.Check for vacuum leaks first.Has anyone messed with the base idle? (idle set screw) this too will cause what you describe

Is there any way I can check for the vacuum leak here at home?

Carefully spray around with carb cleaner while the engine is running.If the engine idle changes, you have found a leak