For those of you who bought a brand new truck, did it run differently during break-in?

SinisterZ71 · July 31, 2019

(2018 Silverado K1500 L83 6L80)

The reason I'm asking is because I bought a brand new ECM for my truck (so I have a spare) and programmed it using TIS2WEB. The problem I'm having with the new ECM is the engine idles high when warm (744rpm commanded) vs. 500 rpm commanded with the stock ECM. Also, the fuel pump doesn't prime when I open the driver's door with the new ECM installed (it does with the old ECM installed).

I'm just curious if this "new" ECM I got thinks the engine is also brand new and is making it run differently because it doesn't think it has any miles on it.

HeySkippyDog · July 31, 2019

I don't think it does. I've had 2 K2s. They pretty much ran the same the whole time.

That is kind of a high idle for warm.

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SinisterZ71 · July 31, 2019

3 minutes ago, HeySkippyDog said:

I don't think it does. I've had 2 K2s. They pretty much ran the same the whole time.

That is kind of a high idle for warm.

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Yea, looking at the scan tool the desired idle speed with the stock ECM installed is 500 rpm. With the brand new ECM installed it is 744 rpm. I'm just trying to determine why it is 244 rpm higher (desired and actual) with the new ECM vs. the stock one that came in the truck. I suspect the ECM I purchased might have an internal fault of some kind (even though no codes are setting).

CamGTP · July 31, 2019

Is the new operating system you installed on the spare computer different than the operating system that was put into the truck on the assembly line?

They do make revisions to calibrations sometimes and I'd be curious if something got changed. I only found one 2018 file on the HP Tuners tune repository and it was posted a while ago, so the OS on that file is like straight from the factory whenever that truck was built.

HeySkippyDog · July 31, 2019

That would be my guess as well. Maybe it's got a more recent factory tune. 700 is a high idle though. I know on some 2014s the high idle push button code worked on the 1500s when it was intended only for the diesels.

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SinisterZ71 · July 31, 2019

The new tune did say it had an update for the OS for diagnostic enhancements for P2101 or something. But when I compare both stock tunes in HPT, all settings are identical. Furthermore, desired warm idle speed is still 500 rpm in the idle table in the new tune. I can't find any idle table in the tune that would explain why it's adding 244 rpm. And no, there's no high idle switch.

cheyenne383 · August 1, 2019

I never noticed any drivability differences but last summer I averaged 14.7mpg with less than 10k miles and this summer I’ve averaged 18.2mpg with 17k and counting. Not sure what all nanny features/cushions may be built into break in but my commute and driving style hasn’t changed in any way and that is almost a 24% improvement.