Getting I2C on ESP8266 to work

I am still trying to make it work with my FM radio module.

The wiring should be correct because when I flashed Mongoose IoT (formerly smart.js)
I could use the following code :

var i2c = new I2C(4, 5);
i2c.do(0x11, [I2C.WRITE, 0], [I2C.READ, 2]);

And have it work perfectly.

On Espruino I used the following (hopefully) equivalent code :

I2C1.setup({ sda: D4, SCL: D5 });
I2C1.writeTo(0x11, 0);
I2C1.readFrom(0x11, 2)

Which results in

ERROR: No ACK
ERROR: No ACK

Can this have something to do with the lack of clock stretching ??