hc sr04 with 1 wire for trigger and echo?

yes, I have working fine. I power it from vcc into the esp32 which is 5v.

Good catch on the echo pin output voltage. I wouldn't of caught that.

I have heard that even though the pins are 3v, it is 5v tolerant. But none the less I should put a couple of resisters in there for a divider on the way back into the esp.

Perhaps the 3v out going to trigger bridged with the 5v out is causing the issue.