1996 Pontiac Grand Prix light headed

Tiny
U156531
  • MEMBER
  • 1996 PONTIAC GRAND PRIX
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 160,000 MILES
I've got a 96 grand prix and for the past year when I drive more than 5 miles I get light headed. Ive taken the car to Midas a couple of times and they can't find a leak. One auto shop said it might be oil burning on the exhaust manifold but I don'rt see any oil leaking and these nothing on the drive way. I do however smell something when I drive the car. I've tried to figure this out on my own and I've gone to great lenghts to eliminate what I thought might be a probelm like a leak in the heater core. I've put in a bypass so no coolant is going through the core and I've flushed all the coolant out of the system because there was a small leak under the hood. I just have water in the cooling system now. I still get light headed and its worse if I have the windows open. If keep the windows closed and have the vents on inside air I don't get as light headed. Any thoughts?
Tuesday, September 1st, 2009 AT 8:12 PM

9 Replies

Tiny
RACEFAN966
  • MECHANIC
  • 5,029 POSTS
OK so have you checked for any fuel leaks at the engine. CHeck the injectors, the fuel rail, and the fuel pressure regulator as well as the fuel lines. Let me know what you find.
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Wednesday, September 2nd, 2009 AT 10:19 AM
Tiny
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No I haven't done that but wouldn't I smell the gasoline if that was the problem? There isn't any gasoline odor.
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Wednesday, September 2nd, 2009 AT 11:58 AM
Tiny
RACEFAN966
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Well you have to be either getting gas fumes or exhaust fumes inorder to get light headed while driving. If there is no exhaust leaks anywhere then it must be gas so I would check for a leaks around the injectors. The fuel pressure regulator and such. Do you have any oil leaks anywhere? Like the valve covers or?
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Thursday, September 3rd, 2009 AT 10:11 AM
Tiny
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I haven't found any gasoline leaks. I also don't see any oil leaks that might be dripping on the exhaust manifold. Someone told me (not a mechanic) that it could be a plugged up catalytic converter that is forcing exhaust back into the system and that could be what is making me light headed. What are your thoughts on this?
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Tuesday, September 8th, 2009 AT 10:10 AM
Tiny
RACEFAN966
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Ok could be but I must ask how it the performance of the car? Does it seem to lake power especially when you climb a hill? I just had a thought have you checked the rear doors and trunk seal? If the trunk seal is not good then it will allow the exhaust to come back into the car. Get back to me.
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Tuesday, September 8th, 2009 AT 11:02 AM
Tiny
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No it doesn't seem to lack performance. I floored it on the way to work this morning and it seems just fine. I'm the orginal owner with 160k miles and I've never had it tuned up. I just thought I'd mention that for more information. Its a 2 door so there aren't any back door seals to check. I did check the trunk seal and it looks ok to me. I've also drained and flushed all the coolant and replaced it with water just in case a leak in the cooling system or heater core could have been what was causiong the problem but that didn't help. I've also brought a home carbon monoxide detector along with me for a couple of days and it never sounded an alarm. I've recently repolaced the pcv valve and that didn't help. I also replaced the conventional oil with a full sysnthetic just incase there was a leak onto the exhaust manifold if that would make a difference but it didn't help. I do smell something but I can't place the oder. It almost smells like deodorant. Any other thoughts or things to check?
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Thursday, September 10th, 2009 AT 9:23 AM
Tiny
RACEFAN966
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Ok you have never had it tuned? If not then I would replace the spark plugs. They should be replaced about every 30000 or it you use platinum then you can 80000 miles. It may be that the plugs are not completely burning the fuel so you are getting some of it into the car through the vents. Let me know what that does for you. If nothing else you get fresh plugs which it is in need of anyway.
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Thursday, September 10th, 2009 AT 10:08 AM
Tiny
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Ok, I've got to ask how the fumes would be coming through the vents? I don't understand how that would happen. Please explain.
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Thursday, September 10th, 2009 AT 12:14 PM
Tiny
RACEFAN966
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OK if the spark plugs are worn to a point that it can't burn all the fuel then it tries to burn the rest in the cat. The vents to the heater pull air in from the outside unless set on recirculate which is only on A/C max. So if it can't burn off all the excess gas it will load up in the exhaust, making the cat smell like a rotten egg and such and can get pulled back into the car through the vents for the heating/A.C. System. Besides if the car has never had the plugs replaced it is way overdue anyway so it won't be money wasted if anything your mpg will increase so it will be money saved down the road. Let me know how it goes after the new plugs. I would prefer A/C delco plugs platinums will last around 80,000 between changes. Gap them to the specs on the label under the hood.
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Friday, September 11th, 2009 AT 10:15 AM

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