OBDII Protocol??

I made a simple sketch that displays speed and rpm on a PCD8544. It works on my car, the Honda, but when I plug it into the Envoy, it does get past the "while (!obd.init());" but it only writes a single zero, the initialized values of speed and rpm to the screen. No new data is relayed from the OBDII converter to the Arduino/display... Ideas? Here is the code I loaded up that works on my Honda but not the Envoy...


[code]#include "U8glib.h"
#include <Arduino.h>
#include <Wire.h>
#include <OBD.h>

int SPEED = 0;
int RPM = 0;
int E_TEMP = 0;
int value = 0;

COBDI2C obd;


U8GLIB_PCD8544 u8g(13, 11, 10, 9, 8); // SPI Com: SCK = 13, MOSI = 11, CS = 10, A0 = 9, Reset = 8

void setup(void) {

// start communication with OBD-II UART adapter
obd.begin();

u8g.firstPage();
do {
initScreen();
} while( u8g.nextPage() );

delay(1000);
// initiate OBD-II connection until success
while (!obd.init()){
;
}

// flip screen, if required
//u8g.setRot180();

// set SPI backup if required
//u8g.setHardwareBackup(u8g_backup_avr_spi);

// assign default color value
if ( u8g.getMode() == U8G_MODE_R3G3B2 )
u8g.setColorIndex(255); // white
else if ( u8g.getMode() == U8G_MODE_GRAY2BIT )
u8g.setColorIndex(3); // max intensity
else if ( u8g.getMode() == U8G_MODE_BW )
u8g.setColorIndex(1); // pixel on
}

void loop(void) {
// picture loop
u8g.firstPage();
do {
updateScreen();
} while( u8g.nextPage() );

obd.readSensor(PID_SPEED, SPEED); //get obd speed
SPEED = SPEED / 1.609344; //convert to mph
obd.readSensor(PID_RPM, RPM); //get obd rpm
obd.readSensor(PID_COOLANT_TEMP, E_TEMP); //get engine temp
E_TEMP = (E_TEMP * 9) / 5 + 32;
}

void updateScreen(){
u8g.setFont(u8g_font_fub30);
u8g.setFontPosTop();
u8g.setPrintPos(1,2);
u8g.println(SPEED, 1);

u8g.setFont(u8g_font_8x13B);
//u8g.setFontPosTop();
u8g.setPrintPos(1,46);
u8g.println(RPM, 1);

u8g.setFont(u8g_font_8x13B);
//u8g.setFontPosTop();
u8g.setPrintPos(60,46);
u8g.println(E_TEMP, 1);
}

void initScreen(){
u8g.setFont(u8g_font_8x13B);
u8g.setFontPosTop();
u8g.setPrintPos(1,2);
u8g.println("Waiting");
u8g.setPrintPos(1,16);
u8g.println("for OBDII");
}[/code]