can not connect to obd-ii

Hey guys,

I am trying to get my uart adapter (model a -- v1.2) to connect to either one of my cars (2011 lexus is250 and 2003 porsche cayenne) and have had no luck. I'm using the 3.3v version and it's connected to my digitx (due) board. I have the rx, tx power and ground connected to the board. I tried the 'hello world' sketch and the led does not turn on at 3000 rpm. I also tried to just print the data to my serial monitor and all i get is "ATZ" repeatedly getting sent with nothing in return.
I'm running the rpm_led_uart sketch as well as this one:
[code]
#include <Wire.h>

/*************************************************************************
* Sample sketch based on OBD-II library for Arduino
* Distributed under GPL v2.0
* Copyright (c) 2012-2013 Stanley Huang <[email protected]>
* All rights reserved.
*************************************************************************/

#include <Arduino.h>
#include <OBD.h>

COBD obd;

void setup()
{
// initialize serial communications at 9600 bps:
Serial.begin(9600);
// we'll use the debug LED as output
pinMode(13, OUTPUT);
// start communication with OBD-II UART adapter
obd.begin();
// initiate OBD-II connection until success
while (!obd.init());
}

void loop()
{
int value;
if (obd.read(PID_RPM, value)) {
// RPM is successfully read and its value stored in variable 'value'
// light on LED when RPM exceeds 3000
digitalWrite(13, value > 3000 ? HIGH : LOW);
Serial.print("RPM = ");
Serial.println(value);
}
}
[/code]

both of them just prints "ATZ"

I checked the connections with a dmm on my protoboard and they were all solid.

I started the car with the obdii adapter connected and also connected it after the car was started, no change
I'm at a loss here. any help would be appreciated.