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Discussion Starter · #1 ·
so i just came back to central NH from a drive to NY. . four hour drive each way about and the viggen did quite well with 167k on it .

One thing i noticed after the trip is that my newly installed GS exhaust system is alot noticebly quieter than before. hard to hear the burble on deaccel now even. . ive had it on now for about 5,000 miles i also just changed the plugs before the trip. .

What caused the exhaust to be this much quieter.. motor runs fine no differences in anything else . . i did have to run 87 gas for a stretch because thats all they had left at the station. . i think this is when i started to notice the quiet tone.

Did the exhaust just get resonated from the long trips both ways. did the cheap gas do somthing ? i cant remember my SE being this quiet after 10's of thousands of miles on the
V1 system .. any ideas or am i thinking too much and itll never sound the same?
 

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Just light highway cruising should be fine with 87 in there, just don't hammer on it until you can fill up again.

The packing in the muffler might have started to fill in, or may just be moist from water in the exhaust condensing, it my rasp back up when it warms up, or may stay that way, hard to say.
 

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Discussion Starter · #6 ·
yeah ive since filled up with 93 and its still alot quieter more resonated sounding. . im hoping there is somthing to be burnt off from that fuel. . i might put a bottle of seafoam in before my next oil change here in a couple of days and see if that does anything.. idk what else it could be, other than that or some water in the ports like you said.
 

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Discussion Starter · #7 ·
you know the more i think about it. . the engine management could very well be the whole cause of this annoyance. i am getting alot better MPG than i was.

I guess through all that driving the car adapted to the highway driving and somehow th back pressure is reduced ?
 

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Discussion Starter · #9 ·
just seafoamed and changed the oil last night. . it does run alot smoother with alot more throttle response. . but under vacuum and boost the car is still alot quieter .

I am going to reset the ECU sometime today and see how that works .
 

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You just burned your exhaust clean. The rough sound was all the carbon buildup in the exhaust. That's also why your getting better gas mileage. A long smooth drive allows the system to burn itself clean. Thus the better MPG. Stop and go driving cause my saab to run rich. I've got a real sensitive O2 sensor that triggers the 'check engine' light when I've been running heavy on the gas. With these older cars the sensors get more sensitive as they wear out. Hard acceleration causes the rich mixture. Too much and I get buildup on the O2 sensor and the check engine light goes off.

I find that a long 2 hour highway drive is always the best way to clean this gunk out. It's smoother because all that carbon buildup has burned off the exhaust.
Now your car is getting good sensor feedback to allow a leaner fuel mixture, better MPG, and a smoother running car.

The fix would be to replaces all those sensors, MAP, O2, VACUUM, and anything measuring airflow and exhaust. Too much to be worth the change.

The rich mixture will also clog the Catalytic converters, just like a stuffy nose. You breath heavy and make a lot of noise. the long drive heats the Catalyst up and the volume of exhaust helps to burn it clean. Another reason the cleaned catalyst breathes better and a quieter sound. Less backpressure.
 

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Discussion Starter · #11 ·
yeah sounds right. . i wish i could get that tone back. . but deff less backpressure in the system. . car runs alot smoother tho i will say yeah. . i have replaced the O2s already so im ok there. i just miss that great burble and tone under wot .

Id rather be getting better mpg and a smoother cleaner running car anyday though, especially with a higher mileage vehicle.
 

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I don't care how much seafoam, techron, etc you put into your car, you are not going to be able to clean all the carbon out of the exhaust system. Maybe you have just become used to the sound, does it come with two or one muffler, if two, cut one out.
 

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Discussion Starter · #13 ·
its not because i am used to it i can tell you that, its the saab sport only one muffler .
 
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