sag / hesitation and woooosh sound
- Troyport
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sag / hesitation and woooosh sound
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
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
- Troyport
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Re: sag / hesitation and woooosh sound
anyone have any thoughts?
- J Wikoff
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Re: sag / hesitation and woooosh sound
I'm wondering if an oil fill breather would change the situation.

WHITE WHINE - 1992 SSE Supercharged 236.26 ci (.040 Over) 15.090 at 90.2 MPH on old engine w/ slipping trans & melted O2 sensor - Gen 3 M62 and matching TB, Gen 2 Pully, Zillamotorsports Ported LIM, YT 1.72 Roller Rockers, SII FPR & Injectors, Hypertech Thermomaster chip w/ 160 Thermo, TransGo Shift Kit, Infinity/Pioneer Speakers & a 10" Alpine Type R Sub, all the watts, 140 amp Alternator, Ricepipe CAI w/ heatshield, Pilot Angel Eye Foglights, Clear Corners, '02 17" Chrome Bent 5's, Magnaflow F-Body Muffler and Hi-flo Cat, Ceramic Coated Ported Exhaust Manifolds, Fan Override, Monroe Reflex struts, red calipers
2009 G8 GT - Sport Red Metallic, loaded, SOLO Axlebacks, Rotofab Intake, Tuned, autodim mirror, removed intake manifold cover, HSV GTS triple gauge pod, two tone red-hot shifter and HSV SuperSport steering wheel, GXP rear sway bar and diffuser, 3.45 diff and various Camaro suspension bits, LED Taillights
- Troyport
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Re: sag / hesitation and woooosh sound
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
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
- J Wikoff
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Re: sag / hesitation and woooosh sound
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?

WHITE WHINE - 1992 SSE Supercharged 236.26 ci (.040 Over) 15.090 at 90.2 MPH on old engine w/ slipping trans & melted O2 sensor - Gen 3 M62 and matching TB, Gen 2 Pully, Zillamotorsports Ported LIM, YT 1.72 Roller Rockers, SII FPR & Injectors, Hypertech Thermomaster chip w/ 160 Thermo, TransGo Shift Kit, Infinity/Pioneer Speakers & a 10" Alpine Type R Sub, all the watts, 140 amp Alternator, Ricepipe CAI w/ heatshield, Pilot Angel Eye Foglights, Clear Corners, '02 17" Chrome Bent 5's, Magnaflow F-Body Muffler and Hi-flo Cat, Ceramic Coated Ported Exhaust Manifolds, Fan Override, Monroe Reflex struts, red calipers
2009 G8 GT - Sport Red Metallic, loaded, SOLO Axlebacks, Rotofab Intake, Tuned, autodim mirror, removed intake manifold cover, HSV GTS triple gauge pod, two tone red-hot shifter and HSV SuperSport steering wheel, GXP rear sway bar and diffuser, 3.45 diff and various Camaro suspension bits, LED Taillights
- Troyport
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Re: sag / hesitation and woooosh sound
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.
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00Beast
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Re: sag / hesitation and woooosh sound
If you shut it off and hold the throttle all the way open does it make the woosh?
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Re: sag / hesitation and woooosh sound
Couldn't hurt to throw a can of fuel system cleaner in there on general principles.
Re: sag / hesitation and woooosh sound
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..00Beast wrote:If you shut it off and hold the throttle all the way open does it make the woosh?



