Anyone experience a p1421 code after UPREV tune
 

Basically title is my question, also related to the code it says its cold start idle control? the Z once in awhile idles high for a couple seconds then goes to normal at start up im assuming the code is causing the idle issues I tried searching and couldn't find an answer or solution on this, just wondering if anyone else has had this come up and if they have found a solution, thanks!

I just had this same issue and my tuner had to disable simple timing in uprev in order for my Z to run correctly, I’m not sure what it is but my early production Z doesn’t seem to like any of the newer features of uprev

I worked with uprev to correct the issue, as long as you have the very latest ROM the issue should be resolved now