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1999 olds eighty eight, not supercharged. forever it seems, there has been a slight sag or hesitation while pulling away from a stop light. Some days worse than others. Never set any codes. Over the course of time, many things have been replaced just as a matter of maintenance or because of failure. The car has 108K on it. plugs, wires, pcv, fuel reg, MAF, oxygen sensor. No vac leaks. If the battery is disconnected for some reason, the car runs great for a few days then it is like the computer teaches the engine how to run crappy. If I use it hard, it runs better, for a few days, until it teaches itself how to run crappy again. I have just learned to live with it, but my daughter might be getting the car, and I don't want her to have any issues.
Has this happened to anyone else?
Also, about 3 - 5 seconds after I shut the car off, I hear a woooosh of air, sounds like the vacuum in the intake manifold is releasing. This is an internal sound, it is not venting to the outside. and yes, the O ring is on the PCV valve... and if the oil fill cap is removed it does not make the car run bad (to, the entire crankcase is under vacuum)
It has had this for almost 80,000 miles. Yes, that long! Mike

anyone have any thoughts?

I'm wondering if an oil fill breather would change the situation.

Thanks for the reply.. Maybe my long post was confusing. The crankcase is not under vacuum. Removing the oil fill cap makes no difference. The woosh sound is in the upper intake and it is the vacuum equalizing to atmosphere about 2 seconds after the engine stops. Maybe this is normal. My 93 does not do this.
In general, the car feels like it is always running lean... for you old guys out there... it is like a carbureted vehicle if the choke pulls off a little too early. Thanks, Mike

The throttle plate doesn't really seal well enough to hold vacuum for a couple seconds. If it does, maybe you need to clean some build up out of the throttle body?

I just cleaned the throttle body last week, it was not that bad, but maybe dirty enough to make a pretty good seal. Honestly, as busy as I am, I haven't paid attention to the woosh sound since. But, it seemed to run a little better, but that may just be my imagination. Still has that lean feeling. The EGR, by the way, is not sticking. Fuel mileage is fine. I'll listen for the woosh tonight.

If you shut it off and hold the throttle all the way open does it make the woosh?

Couldn't hurt to throw a can of fuel system cleaner in there on general principles.

00Beast wrote:If you shut it off and hold the throttle all the way open does it make the woosh?

My 99 SE does the same thing, but when i have my throttle all the way open it doesnt make that sound. What does this mean? Ive cleaned my TB..