97 Olds Aurora keeps stalling

jbataFebruary 2, 2006

I have a 97 Olds Aurora. All in all its been a great car. However a couple times a month it stalls out. Usually I am going about 30mph and all of the sudden it quits. I have to pull over put in park and restart. Or it happens quite a bit when Im slowing down for a stop sign or light. And before it stalls there no sign its going to stall like puttering or anything. So I dont know if its electrical or...? A year ago there was a recall for this probelm of stalling. However we took it in and had the work done but it didnt solve the problem. So I dont know if they got lazy and said they fixed it but didnt or what. I think it was something with a fuel line or pump or something? Any info would be greatly appreciated!

TIA,

jb

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earthworm

If they use an idle air control device as GM is wont to do, then this could be dirty, in need of cleaning.
Some replace this device, but this must be determined to be the cause..
It could be nothing more than a broken vacuum hose...

    Bookmark   February 2, 2006 at 6:40PM
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jbata

So it doesnt sound like anything too expensive to fix, or is it? How could I determine myself what it is or is this something I should have checked out by a professional? Is this a common problem with cars?

TIA,
jb

    Bookmark   February 3, 2006 at 7:24PM
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jemdandy

I'd take it to a professional garage that has the proper diagnostic tools and someone who knows how to use these. It may be the IACS control, but could be something else as well. You wouldn't want to fix the wrong thing. That's costly.

You can find the price of the IACS unit by inquiring at your favorite automotive parts house. These are not hard to swap out. For GM cars, after installing an IACS, you should adjust the control to its nominal position for the first engine start. (Consult a repair manual for this procedure.) The system will automatically adjust it there after. It is interesting how and when this automatic adjsutment is made. Knowing how its done helps to understand the system. (Consult the manual for details.)

On my GM cars, I've seen the IACS wear out by 70,000 miles, while lasting much longer on other models. It's life is very variable. I've taken these apart to look at the design details and found the weak spot is the feed screw that is molded of plastic. Either it or both the screw and nut wears out around its nominal position. The nut either slips or jams at wearout.

The working parts of GM's IACS is a lead screw directly driven by a stepper motor. The motor steps equally well in either direction. A nut on the lead screw moves the air control valve. There is no feedback control, therefore, during the calibration phase when the engine controller resets the IACS to a nominal position, it does not "know" if this was done properly, but assumes the IACS is at its nominal position after sending a series of pulses to the stepper motor. At idle, the engine contoller uses the tachometer signal to sense engine speed and makes minor adjustments to the IACS. In this way, it can keep a nearly constant engine speed under varying loads at idle (provided the IACS operates well).

    Bookmark   February 3, 2006 at 10:17PM
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bucky

It could be something as simple as a dirty fuel filter. Has the fuel filter ever been changed?

    Bookmark   February 12, 2006 at 11:56AM
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earthworm

Bucky, is correct - all the service items must be up to date when problems are encountered..
Having read Jemdandy's short treatise on the idle air control, I'd guess that one could test it with an ohm-meter; or an external measured power supply which could reveal looseness in the mechanism..

Back in the 60s,70s, we used to make an educated guess and use a test component - this would isolate a problem, making the diagnosis accurate..But the average DIY has not this luxury.....

    Bookmark   February 12, 2006 at 12:39PM
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