First upshift with a bump

I have Mazda 6, 2004. For about a week now the first upshift (1->2) after cold start, sometimes even second one (2->3) happens with a “bump”. Any ideas?

How many miles?? Is the check engine light on?? Has anyone scanned it for codes??

transman

The first step is to check the fluid level and condition.

33000, no engine check light (it means there are no codes to scan, right?). Thanks for replying! It seems like this first 1->2 shift happens at lower RPMs than it does after I drive for a while. Need another cold start to verify.

fluid level is good, color too, thanks for replying!

Make sure it isn’t overfilled with transmission fluid. Check it according to the owner’s manual. Old transmissions in cold, cold weather (GM turbo 350) can shift hard like that.