99 Olds Intrigue - RPMs remain accelerated even while idle??

[arcy]

Hi, my 99 Olds Intrigue has been doing something wacky for the past 13 months - intermittently. After driving on steady speed (60-70mph) for approx 1/2 hour on expressway, then slowing down into residential roads, my vehicles' RPMs stay stuck. If at a stoplight, they remain no lower than 1.75 to 2.5, if I step on the accelerator, they go up to 2.75 to 3.75 and do not go down again to idle (.9). Once I move past the light, the car remains accelerated. Sometimes this gets reset by shifting the car to park, shutdown and restart. But doing so, causes the RPMs to flare up to 4.0 and stay there till I shut down the car. If at this point I shift back to Drive (whiteout shutdown), it causes my car to jerk as the transmission tries to engage to drive. There have been some cases where shutdown/restart does not reset this malfunction, and a few times the 'check engine soon' light turns on.

I have taken my vehicle to the dealer several times, as it is still under warranty. This happens intermittently, but I have manages to stop by while it is happening. They plug the computer in, and the only error they find is that the RPMs are running high (CODE P0507 =Idle speed high). They have managed to replicate the malfunction. So far they have replaced the mass airflow sensor, replace and reprogram PCM, and now they are cleaning the throttle body.

Any suggestions as to what this problem might be.
Thanks
Arcy

[canatto]

My 1997 Ford Contour used to have intermitent idle speed problem. it wasn't high reving idle but that the engine would bog down to a very low rpm almost die on me then rush to 3k rpm or so then either drop to normal idle speed or start another cycle. It really died a couple of times but most of the times it would come back to normal by its own or after briefly blipping the throttle and revving the engine. The Contour never set the check engine light. I tried to clean the Idle Air Control Valve (a solenoid valve that bypasses air around the throttle body) by disconnecting the idle air bypass tube and spraying in some throttle body cleaner, and that seemed to have corrected the problem.

My Intrigue is 2000 GLS with 3.5L engine. I'm new to this car (3 weeks), and it doesn't have the idle problem as yours does, so I can't tell anything from experience. But I would guess the problem is with the idle air control devices whatever/wherever they are. Your OBD-II code of P0507 actually says "Idle Air Control System Mulfunction - RPM Higer Than Expected". So I would have the idle air control system checked up.

I noticed when I was changing the air filter the other day that there was no bypass air tubes branching off the main air conduit to get around the throttle body, so I began to wonder how this car sneaks the idle air to the engine......unlike the Ford Contour that any air that enters the combustion chamber gets metered off the mass air flow sensor so that there are a couple of air tubes branching off the main air conduit between the mass air flow sensor and the throttle body, the Intrigue has a clean air conduit. Now I think I need to buy a service manual.

I doubt Intrigue engine controls the idle speed with throttle body, because the amount of air an idling engine needs seems to be too small for a throttle body to control with precision, what your dealer did by cleaning the throttle body was trying to rule out throttle leakage, but again I could be wrong.

I know I didn't sound much helpful if any. I'm just throwing in a little thought hoping it could help.

There is a discussion group that seems to be of more traffic, you may want to try your queation there as well:
http://modernolds.proboards13.com

good luck!
Shaoyi

Originally Posted by arcy

Hi, my 99 Olds Intrigue has been doing something wacky for the past 13 months - intermittently. After driving on steady speed (60-70mph) for approx 1/2 hour on expressway, then slowing down into residential roads, my vehicles' RPMs stay stuck. If at a stoplight, they remain no lower than 1.75 to 2.5, if I step on the accelerator, they go up to 2.75 to 3.75 and do not go down again to idle (.9). Once I move past the light, the car remains accelerated. Sometimes this gets reset by shifting the car to park, shutdown and restart. But doing so, causes the RPMs to flare up to 4.0 and stay there till I shut down the car. If at this point I shift back to Drive (whiteout shutdown), it causes my car to jerk as the transmission tries to engage to drive. There have been some cases where shutdown/restart does not reset this malfunction, and a few times the 'check engine soon' light turns on.

I have taken my vehicle to the dealer several times, as it is still under warranty. This happens intermittently, but I have manages to stop by while it is happening. They plug the computer in, and the only error they find is that the RPMs are running high (CODE P0507 =Idle speed high). They have managed to replicate the malfunction. So far they have replaced the mass airflow sensor, replace and reprogram PCM, and now they are cleaning the throttle body.

Any suggestions as to what this problem might be.
Thanks
Arcy

[GMMerlin]

Idle on that vehicle is controlled by an IAC valve driven by the PCM....Intermittant operation could be caused by a sticking valve or intermittant short to power or ground on any of the 4 wires that control the IAC valve....

[illinoiswronski]

On the 3.5, the IAC is built in to the trottle body -- the air passages are in the top of the TB, the IAC valve bolts into the top of the TB from the back of the engine.

The IAC is easy to remove, just two bolts and a connector so you could pull it out and check it to make sure that it moves. Also make sure that the IAC air passages are clear and that the TB closes all the way (if it sticks open the the IAC can close all the way and the engine will still race).

Does this problem show any relationship to you using the cruise control?

[illinoiswronski]

No replies from you so I assume that this has not happened again lately.

After thinking about this one a bit more I do not think that this is a problem with the IAC valve. I don't think that the IAC can pass enough volume of air to rev this engine as high as you describe. This has to be the TB sticking open some how.

[arcy]

Hi everyone... Happy New Year 2004 !!

Just got back from Holiday travels. I got the car back from the dealer and they cleaned the throttle body. One day later on my my way to the airport for my travels it did it again. This time, the Service Engine Soon light came on. When I picked up the car from the airport parking lot 2.5 weeks later, the light was still on, but turned off before we could get home. We also noticed that the cruise control is not working anymore. We had at some point suspected it might be related to the cruise control, because it seems to stay stuck accelerated, but have no confirmation on this yet from the dealer service dept. Also, one other thing changed - now this problem is happening even after cold starts - early morning and soon after starting.. Before it used to only happen after the car had warmed up. The Service guy told me we was talking directly to a GM expert to get advice on this diagnose, and he was glad to hear about the service light, so maybe they get a different error. I have also given them the advice you gave me from this posting, just to try to help. My car goes back to the shop on Monday Jan 12th, for about another week. I will post the results on this site. I have also been contacted by others experiencing this same problem. So, am I think it can benefit other if I post the progres on this board.

Thank you for you help.
Arcy

[white]

Hi there -

I am experiencing the same problems with my car and I have done some research through family, and my cousin suggested that these cars are known for the valley gaskets in the intake manifold to leak and reseal....does anyone think that this could be the possible culprit for this? Someone else told me that if this were the problem, that I would be leaking oil also????