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Old May 29, 2014 | 06:52 PM
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Default Exhaust smell inside car

Okay, here's a new one -

This happens 3 or 4 times a week.

I'll be driving along, windows up, and everything's all good. I'll start accelerating a bit aggressively, and all of a sudden, the inside of the car starts filling up with exhaust fumes.

(1) If there is a leak, where could it be coming from?
(2) If my windows are closed, from where can this exhaust smell come in from?

Thanks

oh, 1998 Camaro Z28 M6; engine has about 145,000 miles on it
oil changes are done regularly
still has both stock CAT converters
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Old May 29, 2014 | 07:15 PM
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You can get some exhaust fumes or other odors through the vents in the cowl under the windshield. Its odd if the smell is very strong since you still have cats assuming they are still working.

Any exhaust leaks that you can hear?
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Old May 31, 2014 | 10:23 AM
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Header or the collector on the passenger side is leaking. Replace header gasket and clamp on collector. Cheap fix but time consuming.

Chad
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Old May 31, 2014 | 11:05 AM
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Sounds like more than just a leak. I bet it's the cats starting to go bad.

At idle they are still good enough to do their job, but as you get more exhaust volume going by accelerating hard it starts to overwhelm the cats and they are not able to handle all the smell.
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Old May 31, 2014 | 07:52 PM
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Originally Posted by Bramlok
You can get some exhaust fumes or other odors through the vents in the cowl under the windshield. Its odd if the smell is very strong since you still have cats assuming they are still working.

Any exhaust leaks that you can hear?
No leaks that I can hear. Yeah, gonna try the smog place I go to to see if I would pass a smog check. Also, there are absolutely no leaks appearing under the car while it's parked.
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Old May 31, 2014 | 07:54 PM
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Originally Posted by redtan
Sounds like more than just a leak. I bet it's the cats starting to go bad.

At idle they are still good enough to do their job, but as you get more exhaust volume going by accelerating hard it starts to overwhelm the cats and they are not able to handle all the smell.
Yeah, I will be making an appointment with my local smog check guy to see what his machine says. Again, they're the stock cats.
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Old May 31, 2014 | 07:57 PM
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Originally Posted by ss4chad
Header or the collector on the passenger side is leaking. Replace header gasket and clamp on collector. Cheap fix but time consuming.

Chad
Well, I can only hope it's not the header gaskets as I just had them changed back in Aug '12. Collector leak? That may be another thing.
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Old Sep 5, 2014 | 10:54 PM
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Okay, UPDATE...

So, I have an electric cutout located almost underneath the rear passenger seat. Had it for about 10 years now. ONLY in the last 4 months have noticed this problem: With the cutout open, after driving about 15-20 minutes, exhaust smell starts to fill up the inside. BUT, as soon as I close the cutout, the smell goes away (presumably exiting out the tailpipes). Again, in the previous, 9.5 years, this has NEVER been a problem. Need some smart minds to help me out with this before I go spending money for someone to diagnose the problem.

Thanks.
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Old Sep 6, 2014 | 03:01 PM
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You sure the cutout is closing all the way? Look under and see. Or close the cutout, and once closed, press the close button again for a second or two to see if you hear a change in loudness. If the car gets a little quiter when you press the botton, that means the cutout doesn't close all the way.

When my old exhaust pipes started to rust through, I had few small pinholes that allowed the car to smell like exhaust fumes.
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Old Sep 6, 2014 | 05:08 PM
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By exhaust smell, do you mean running rich/fuel smell like an older carb vehicle? The car might just need some basic tune-up TLC. Exhaust underneath the car will find its way in somewhere..no car is sealed THAT well. This is also exacerbated at low speeds/idling as at higher speeds airflow under the car takes the exhaust away. Maybe before the car was running more optimally and the exhaust from the open cutout didn't smell. When everything is working properly, the exhaust wont smell like much at all..carbon monoxide is dangerous like that...odorless.

Last edited by Mercier; Sep 6, 2014 at 06:44 PM.
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Old Sep 7, 2014 | 09:43 AM
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LSX Man - Yeah, that's the thing with the cutout out open, everything's great for the first 15 minutes or so, then the exhaust smell comes. But as soon as I close the cutout the smell goes away. That's it. All I have to do is close the cutout, and no more exhaust smell entering the inside of the car.

Mercier - yup, did the tune-up back on 04/20/2009. And yes, the smell is similar, and quite pungent! Not like rotten eggs at all. And this problem didn't start until about 4-5 months ago.

Oh, and both cats are the stock ones if that helps.
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Old Sep 7, 2014 | 11:30 AM
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5 year old tune-up? Might be worth looking into. If it's a gaslike smell you are basically running rich for whatever reason. Tune-up, tune, parts, etc. Cats wont correct a rich condition but a rich condition can kill cats. Clean your MAF with appropriate electronics cleaner and take a look at your O2 sensors.

A well tuned fuel-injected LS wont have a carb-gas smell to it if tuned tight unless you have some massively overlapping cam.

Unlikely but you could have lost some drain plugs in the floor pan area due to dry rot or similar, allowing more exhaust into the car. Also the door seals. But again, gassy smell under car will find its way in there no matter what. Otherwise people would suffocate in cars on long trips.

Last edited by Mercier; Sep 7, 2014 at 11:36 AM.
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Old Sep 7, 2014 | 01:42 PM
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Maybe the shifter boot under the console has a rip/hole, or maybe one of the body drain plugs is missing?
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Old Sep 7, 2014 | 03:00 PM
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get off the keyboard and do a god damn tune up!
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Old Sep 7, 2014 | 05:11 PM
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Originally Posted by Mercier
5 year old tune-up? Might be worth looking into. If it's a gaslike smell you are basically running rich for whatever reason. Tune-up, tune, parts, etc. Cats wont correct a rich condition but a rich condition can kill cats. Clean your MAF with appropriate electronics cleaner and take a look at your O2 sensors.

A well tuned fuel-injected LS wont have a carb-gas smell to it if tuned tight unless you have some massively overlapping cam.

Unlikely but you could have lost some drain plugs in the floor pan area due to dry rot or similar, allowing more exhaust into the car. Also the door seals. But again, gassy smell under car will find its way in there no matter what. Otherwise people would suffocate in cars on long trips.
Thanks! Also, no codes being thrown anywhere. Will definitely take a look at this.
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Old Sep 7, 2014 | 05:13 PM
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Originally Posted by _JB_
Maybe the shifter boot under the console has a rip/hole, or maybe one of the body drain plugs is missing?
Definitely will check those plugs! Thanks!
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Old Sep 7, 2014 | 05:16 PM
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Originally Posted by Mercier
5 year old tune-up? Might be worth looking into. If it's a gaslike smell you are basically running rich for whatever reason. Tune-up, tune, parts, etc. Cats wont correct a rich condition but a rich condition can kill cats. Clean your MAF with appropriate electronics cleaner and take a look at your O2 sensors.

A well tuned fuel-injected LS wont have a carb-gas smell to it if tuned tight unless you have some massively overlapping cam.

Unlikely but you could have lost some drain plugs in the floor pan area due to dry rot or similar, allowing more exhaust into the car. Also the door seals. But again, gassy smell under car will find its way in there no matter what. Otherwise people would suffocate in cars on long trips.
Also, thing that caught my attention was that none of the other fpbody owners in my club have had to do any tune-ups in less than spans of 8 years. Why I was figuring that a tune-up less than 5 years ago shoulda been okay.
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Old Sep 7, 2014 | 06:48 PM
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How does it run when you start noticing the smell, does it seem down on power..
My first thought is a O2 sensor is going out. I'd have a tuner run some data logs on it, with mainly watching A/F ratio, and O2 sensor readings .

Last edited by 99Bluz28; Sep 7, 2014 at 06:58 PM.
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Old Sep 7, 2014 | 09:37 PM
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I would check seals on the rear hatch, The area directly behind the car is a low pressure area and if not sealed completely it will allow exhaust fumes inside the car.
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Old Sep 7, 2014 | 10:58 PM
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Originally Posted by 99Bluz28
How does it run when you start noticing the smell, does it seem down on power..
My first thought is a O2 sensor is going out. I'd have a tuner run some data logs on it, with mainly watching A/F ratio, and O2 sensor readings .
No. Not at all. Goes like a champ! Tuner MIGHT just be my next option. But all tuners around here wanna charge almost $500 for a few hours work. I am also almost thinking about just replacing all 4 O2 sensors.
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