Stinky at Cold and Warm Start

[allen918]

Were you ever able to remedy this issue? Recently purchased a 2015 Yukon and I’m having a strong exhaust smell at idle. When driving and then parking it doesn’t smell bad til it sits idle for a few minutes. I can drive and park get close to the tail pipe and no smell for about 1-2 minutes then it gets really strong, drive some more it goes away til 1-2 minutes of idling and it’s back. It happens at start up or after driving and a few minutes of idling. Any advice would be greatly appreciated.

 

[B-train]

What kind of driving do you do? Short trips, slow in town, or highway? Short trips can make them stinky because the cats don't get super hot and have time to burn clean. The newer motors run richer than previous generations for emissions reasons to keep the cats hot.

My 2017 with the 6.2L will have a definite raw fuel smell on cold start for a minute or so, as will my 2008 with a 6.2L. I haven't noticed any weird smells when warmed up though. A lot of times I'll run them in my shop for maintenance with the door closed when it's cold out and never had an issue.

You could try running some good fuel system cleaner in the next tank of gas, cleaning the throttle body, and checking the condition of the air filter. If it has over 100k and never had spark plugs, do them as well.

 

[Doubeleive]

this is why GM made the vehicles shut off after idling for a while because people park them in a garage and "forget" it is running.
most if not all vehicles will stink of fuel particularly at cold start up and in a garage, in a enclosed space or if you stand by the exhaust.
if you want to end your trip early just park it in the garage and pipe the exhaust in the window and have a nice dirt nap.
every vehicle I have ever owned has done this.
you will smell it more in the winter, that is normal the c02 gases will linger longer in cool air
now if you are having poor mpg or something going on abnormal other than just "smell" then of course check it out.

 

[allen918]

Thank You for the reply! I drive a mix of in town and highway it doesn’t matter if I drive for five miles or fifty miles when I stop and let it idle after driving it’s fine then after a few minutes the exhaust get so strong I have to turn the Yukon off. I have drove 100+ plus miles and get home leave the Yukon running in the driveway for a few minutes go back out to leave and the exhaust smells like an old carbureted car that’s running rich. I have replaced spark plugs, air filter, MAF sensor, ran one bottle of BG44K in the fuel tank, cleaned throttle body. It’s weird that it doesn’t do it til it has set idle for a few minutes. Also no CEL.

 

[Miami-Dade]

Were you ever able to remedy this issue? Recently purchased a 2015 Yukon and I’m having a strong exhaust smell at idle. When driving and then parking it doesn’t smell bad til it sits idle for a few minutes. I can drive and park get close to the tail pipe and no smell for about 1-2 minutes then it gets really strong, drive some more it goes away til 1-2 minutes of idling and it’s back. It happens at start up or after driving and a few minutes of idling. Any advice would be greatly appreciated.

OP has not been here since 11/2023...If it was anything serious I would have been dead already. I now have 165K miles.

I still have the original plugs in it but doubt new plugs would help as the smell has been around since day 1.

 

[Doubeleive]

Thank You for the reply! I drive a mix of in town and highway it doesn’t matter if I drive for five miles or fifty miles when I stop and let it idle after driving it’s fine then after a few minutes the exhaust get so strong I have to turn the Yukon off. I have drove 100+ plus miles and get home leave the Yukon running in the driveway for a few minutes go back out to leave and the exhaust smells like an old carbureted car that’s running rich. I have replaced spark plugs, air filter, MAF sensor, ran one bottle of BG44K in the fuel tank, cleaned throttle body. It’s weird that it doesn’t do it til it has set idle for a few minutes. Also no CEL.

all good maintenance things so you didn't waste your money, unless you get a code or are having poor mpg or some other type of driveability issue then I wouldn't worry about. If it turns out to be a cat it will pop a code eventually.