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x15 cold idle boost fluctuation. - Printable Version

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x15 cold idle boost fluctuation. - marek4792 - 11-23-2022

2019 X15 Performance 430k miles, EGR tuneup at 410k miles. So when starting the truck for the first time, it will idle with steady boost in its SCR warmup mode (not demandated) and about a few minutes in the turbo will start boosting up and down 2-3 pounds whistling on and off until bumped into hi-idle, engine rpm is steady the whole time and doesn't surge at all.
Just wondering if this a normal thing I'm overthinking or do I got something tweaking out besides the nut behind the wheel.


RE: x15 cold idle boost fluctuation. - tree98 - 11-23-2022

Maybe the VG ring is starting to wear and not holding position well?? Did you monitor with insite to see if the ECM is commanding it up and down? 430k miles on a non demandated turbo is probably close to a full life.


RE: x15 cold idle boost fluctuation. - marek4792 - 11-23-2022

Thanks! I'll look into that, just changed out the speed sensor in the turbo recently because it crapped out and after that I guess I just noticed the fluctuation. Still also got to check the mechanical side for air/exhaust leaks that aren't so obvious before I fire off the parts cannon at this thing.


RE: x15 cold idle boost fluctuation. - Rawze - 11-24-2022

It is most likely the EGR pressure sensor not seeing the right pressure when its cold and air is still dense. It is likely not an issue unless it gets excessive.. to which the EGR circuits need cleaning out including the Delta-p block and maybe even the egr cooler itself if it gets dirty enough.

ref: http://rawze.com/forums/showthread.php?tid=2506&pid=22458#pid22458