Ebay HC SR04 Ultrasonic, limited range?

So im having a really strange issue with some ultra sonic HC SR04 based sensors, the cheap ones on ebay.

So here is the deal I have 5 sensors, I tested all 5 on a Propeller based DevBoard. They all worked fine. The sensors read that my wall was 115cm away. I also put my hand in front of them moving it back and forth and the readings appeared accurate.

I then pluged the sensors in to an Arduino, put my hand in front of them and the readings seemed fine. When I moved my hand the sensor said 0cm and wouldnt detect my wall. The Arduino was in the exact same spot as my Propeller BOE. So I then took a book and tested the range of the Arduino, I couldnt get more than about 50cm. This is odd that my range drops when using an Arduino...

Im guessing it may be a software, I downloaded the new ping library along with it demo. This library claimed to be better than the standard one and supports the ebay sensors.

Anyone use these ebay ultrasonic sensors with no issues, anyone have an idea why my range is cut down so severly when using Arduino.

Could it be that your first tests used a different power supply? My first thought is that the reduction in range is due to a reduction in power of the ping.

I was used the same wal wart, first board had a switching regulator, the Arduino had a 5v linear regulator rated at 1 amp only powering 1 ultrasonic and the arduino. I would hope that is a good enough power supply. Im acually using the sensor just fine on another propeller board using the same type of 5v linear regulator that is on my arduino board.

Can someone verify newping 1.5 works at full range with these sensors?