Car has 235k miles, last night while driving home (city-driving), the engine surged to 4000rpm, during relatively gentle acceleration from a spot. it went like this:
-light turned green, light gas to make the turn
-I increased the pressure to a constant less than halfway down
-car upshifted
-a second later, the rpms jumped from 2300 to 4000, and it was as if it revved in neutral, so I wasn’t accelerating in that moment, it then slowly came down back to 2300 in 3 seconds (meanwhile I had eased pressure).
-i was probably going 30mph, accelerating to 45mph
The car gets driven approx 650 miles a week by dad so I’ll ask if he recognizes anything similar. However could the transmission be slipping? It normally shifts well.