Sometimes, when I drive the car first thing in the morning, the car slows down despite me keeping my foot on the accelerator, and even pressing it more, then the engine kicks in slightly later than it should, and revs highly and loudly. This will repeat maybe about 3 times. Only happens in the morning. Is this normal?
This only happens to me once every cold start. Are you sure that it happens to you two or three times? Is that in the same driving session or two to three starts after stopping for a short time between? If it is in the same drive session, that is not normal. It is normal to have this transition if you ask for power while still in stage 1 of the Prius warm-up. If you can drive with gentle acceleration and 25 MPH or under for the first couple of minutes until the car transitions to stage 2 then work with the car. However, don't compromise safety – if you need power, press the accelerator as necessary and the car will accommodate albeit with a bit of a eye blink hiccup over the transition. If you want to learn more about the 5 stages of Prius warm-up, click the link in my signature.
This is only in the morning 1st time, then never again. I’ll be below 20mph and it’ll still do it for some reason. Should I start the car and wait until stage 1 is complete? How would I know when stage 1 is complete?
No, it is not necessary to wait. Did you read the Hybrid Warm-up: 5 modes of Prius Operation link as I suggested? That should answer your how do I know question.
