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91 Grand Prix rotten egg smell


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01-23-02, 04:30 PM   #1  
91 Grand Prix rotten egg smell

When Im driving on the hiway and when I park it, my car smells like rotten eggs. My boyfriend says it's the catalytic ? converter. He changed the spark plugs thinking maybe it was not tuned up an dumping unburned gas down there but it still does it, any ideas so I can look smart and tell him???

 
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01-24-02, 02:22 AM   #2  
Joe_F
A couple of things:

1) The O2 sensor should be changed as a matter of course and a maintenance, not failure item, so that is a must.

2) Assuming it has been tuned up completely and is not misfiring, and mechanically sound:

a) Certain brands of fuel will cause the smell due to higher sulfur content. Try a different brand and station for fuel.

b) When the converter has broken down it will sometimes smell like that. Might come and go.

c) Certain converter designs are condusive to this odor. My mother's 1993 Saturn did it for a while when it was new. The dealer claimed it was the fuel, which I promptly refuted because I had fueled up at probably 25 different stations in three states. I finally got it out of Saturn that 1994 models had a different converter composition which "eliminated" the odor. Actually, the car's smell went away after time.

I'd start with the O2 sensor and run a code check to make sure nothing's out of whack sensor wise. This is an old style OBDI vehicle. See my post "The Basics" or Knuckles www.batauto.com for how to pull and read your trouble codes.

Let us know what you find.

I never was a fan of those FWD models in Pontiac that shared their names with their much superior rear wheel drive 80's and 70's counterparts . Lol

 
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01-26-02, 05:55 AM   #3  
h2mach4
I just recently did a lot of reading on which octane fuel to use. It all boiled down to...use the octane recommended in your owners manual. Many people think they are doing their car a favor by running high octane, but they are not. The rule of thumb is to run the lowest octane possible, without experiencing engine ping (or knock). High octane burns slower to prevent ping in high compression/high performance engines. If you are running high octane, some unburnt gas is probably coming through your exhaust, and causing the smell. I also believe they stated that over time running high octane can eventually clog your catalyitic converter. A clogged converter would commonly cause power loss, especially noticable when starting from a stop and climing hills. I try 2-3 tank fulls of a lower octane.

Cheers,
AL

 
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01-26-02, 04:18 PM   #4  
Joe_F
I agree with you about using the fuel the owner's manual recommends and stepping up only as necessary.

However, using a higher octane fuel will not clog your cat over time. It is just an unnecessary expense, nothing more.

The computer on most cars can compensate accordingly. High end and high compression engines usually require premium fuel.

 
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