Transmision do not change fron 1st to the 2nd speed

I have a 99 Honda CRV with 102000 miles on it. I have noticed that when going p a hill or with the 5 passengers the car is having a hard time to change the 2nd speed. The engine goes up to 4000 rpm before it changes and very often don’t even changes. I took the car to a transmission shop with the idea that my transmmission was the problem but they said , it itsn’t . That I should make a tune up to the car because the problem was the engine and not the transmission.

Yes, check the engine tune. Is the CEL on? A plugged up exhaust (for whatever reason) can also sap power…

have a 99 Honda CRV with 102000 miles

And how many transmission fluid changes so far? If that is original fluid in there, then … Next time change the fluid more often. No flushes, just a change with dripping the pan and cleaning the filter.

That said I agree that the general condition of the car needs to be checked. Caddyman’s advice should be followed.