Exhaust smell in Air Conditioning at idle

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May 25, 2005
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So I've replaced the pcv and hoses but have been getting an exhaust smell in the vent at idle. Driving down the highway you don't smell anything. I don't see any exhaust leaks anywhere. What would be a good way to track down where it's coming from? I've never had a car let alone known anyone with this issue. Thanks. It's my 2005 Dodge Neon.
 
I probably should have mentioned that the smell was there before i replaced the pcv and hoses. It idles smoother but not perfect. Not sure where the smell would be leaking from. I don't see anything apparent.
 
It's an odd problem. I don't think I noticed it with the heat on but I can't remember. The weird thing is that the smell goes completely away while driving. Not sure where there could be a leak that the A/C would pick up.
 
Is there any emission equipment (charcoal canister) over on the passenger side firewall that could be providing fumes to the cowl?
 
As I'm currently sitting in a parking lot in park with the A/C on I don't smell the exhaust. It seems like it's only in drive when sitting in traffic or at a stop. This seems really weird. I'll check the charcoal canister.
 
Are you sure it's not coming from the car in front of you?
Additionally, stops can be a little "laden" with exhaust at times, watch that. Also be aware of any tail wind which may move exhaust gas forward toward your intakes.
Make sure the engine compartment is sealed away from the air intakes at the cowl. Sometimes rubber seals cam become loose or missing over the years.
Other than that, the electric fans would "kinda" keep the exhaust smell diluted, since they ALWAYS run with the A/C on.
 
Charcoal cannister leak would be a gasoline smell, not an exhaust smell. If you're certain it's an exhaust smell it could be a small exhaust leak closer to the engine that you can pick up at a stop but then when the car is moving the air flow dissipates it. Check your exhaust manifold, and the flex pipe for leaks. Generally you can hear a leak or you'll see black soot around a leak.
 
You have a small exhaust leak under the hood near the fresh air intake for your HVAC. You should never smell exhaust inside no matter what your HVAC is set to. Best way to track down is to have a helper hold a rag over the tail pipe while you go investigating.
 
The exhaust donut gasket on the 1st gen Neon were a known common failure point, the powertrain was pretty much a carryover from 1st to 2nd gen so the problem probably continued on.
 
My '99 does this sometimes. I suspect it's just oil burning off from a weep. It doesn't do it all the time, and I've replaced the VC a few times, so it's not that (I think), but I can see more than one weeping spot on the engine.
 
Check the donut gasket at the manifold, very common to get exhaust in the cab if it’s leaking there and they go bad pretty often.
 
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