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Discussion Starter #1
Hello everyone,

Have a 17’ with 52k on it and was wondering if anyone had a similar experience or could help me figure out what’s going on.

I pulled away from a stop sign and had a bunch of white smoke come from the tailpipe but then it stopped and then after a couple more stops it did it again about 1 month ago. I haven’t had large amounts of smoke happen again but a couple people have told me that a small amount of white smoke comes from my tailpipe when pulling out of a parking spot for example. Coolant is at the same spot it’s been at for months, fuel mileage is same as normal. Checked injectors all reading close to the same at idle and slightly above. No dash lights. Not sure if it’s a regen cycle. Any help would be appreciated. Thanks.
 

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My guess is on regen cycle. You should be able to tell if you are in a regen during this based on your instant mpg then vs. what it is normally. If it’s lower, then it’s a regen.

Other than that, I’m not sure.
 

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Would a regen start right after starting the vehicle? Just a little worried my warranty will run out here in about 8k miles and then something major is going to happen.
 

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It could, if it had been trying to go through one prior to you shutting the truck off. It has to complete a regen fully without being interupted.
 

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Interesting, I would think I would have noticed the white smoke before on previous cycles but maybe not.
 

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And that may not even be it. Although, I just did a search and this post from a full size 6.6 LML Duramax forum seem to have the same issue. Different engine but same idea. Normally, one would think with all of the emissions equipment on our exhaust pipes, you wouldn’t see any smoke ever. I mean, don’t see black smoke on new diesel vehicles.

However, their theory is that white smoke (which, on a diesel, white smoke usually mean sunburnt fuel is getting past things, thus why you have white smoke) is coming from the 9th injector on their trucks (as they have a V8, they have a 9th injector, whereas we have an I4 so we have a 5th injector inline on the exhaust) when it goes to add fuel when doing a regen burn. Normally, you wouldn’t see anything, but they are thinking the DPF is cracked somehow, so fuel is getting by and then you get white smoke. It makes sense and could possibly be your issue. Not sure how you would tell, but if the truck is still under warranty, I would make sure to go back and make GM take a look and fix it if need be.

Link to the thread I was referencing:
https://www.duramaxdiesels.com/forum/archive/index.php/t-78807.html
 

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I noticed a bunch of white smoke coming from my truck on the freeway once. Got curious and plugged in my OBD bluetooth thingie and fired up OBD Fusion, sure enough, it was in the midst of a regen. The smoke lasted for a minute or so and stopped. The regen continued for another 15 minutes or so, it showed 8% soot level when it completed.

I am not worried at this point. The truck has a GDE tune on it and regens only occur every 725 miles or so. Have only noticed it the one time, it was a cool day (around 45 degrees) with some moisture in the air and no doubt the exhaust was super hot. I guess I will keep an eye on it though.

Edit 10/16 - Was on a long trip to and from Utah, happened to monitor another regen from start to finish, no smoke that time. The regen lasted for 20 freeway miles at 70 mph.
 
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