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Discussion Starter · #1 ·
Hey, This morning when I started my 17 duramax I was startled by the engine RPM gently cycling up and down ata about a two second frequency. I immediately fired up my Bluetooth ODB reader but there were no trouble codes. It cycled like this without interruption until I briefly gave it a bit more fuel and then it stopped. I have not had this happen before. It was a bit cooler this morning but still above 60. A subsequent restart did not produce the problem. Has anyone else experienced this? I'm wondering if it might be due to some bad diesel.
 

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Discussion Starter · #6 ·
I did read your thread about this. In my case I did not shut off the engine, just gunned it a little and it stopped cycling. Has not done this since, but no longer as cold as it was. My BIL who knows a good bit about autos thinks maybe the ECU is trying to warm something up by doing this. Hmm... not sure about that. Next time yours does this try gunning the motor to stop the behavior.
 

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My guess would be it's something in the tune that not quite right.

Idle rpm probably not set high enough and the ecm is tryin to compinsate. It should learn itself out which is why it goes away and doesn't come back.
 
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Did you check settings in MyLink? There's a feature you can enable which does this to get the engine warmed up a bit faster so it's not cold when you start driving on the road. I forget what exactly it's called, but it's something along the lines of Increased Idle. Particularly helpful for a remote start so you don't have to sit there waiting for the engine to warm up before you hit the road in cold weather.
 

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My stock truck did this once 4 months ago, and then steady for alittle over a week recently before I was able to get it in to be checked out. Chevys scan equipment produced a stored fuel pressure regulator code and Chevy re flashed the truck. Haven't had an issue since


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