fIRST CHECK THE JETS IN YOUR CARB, THEY HAD A BATCH COME IN WITH THE WRONG JETS INSTALLED.
Trouble code P1506 means: Idle Air Control Overspeed Error
The idle is automatic. If the speed is not corect then you have to fix the problem with the idle motor.
why does my vr commodore idle rough when at complete stop
May be idle position sensor.
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U need to clean the throttle body and also clean the idle air control vavle
Before you can fix the idle problem on your Vauxhall Frontera, you need to find out the cause of the problem. If the problem is with the fuel pump or fuel filter, they would need to be replaced.
Correct the idle by adjusting the idle screw on the throttle body if all else fails replace the idle control module located upper center of firewall usually. Hope this helps
check your idle control valve located behind the engine
You don't, fix the vacuum leak that's causing the eratic idle conditions
To fix high idle problem on a 1996 VS Commodore, first locate the idle air control valve. Unscrew and unplug electrical connector running to the valve. Turn the valve over and clean the sensor for debris.
http://www.jdmuniverse.com/forums/how-tos-tutorials/90246-honda-fast-idle-valve-fiv-pulsing-idle-fix.htmlGo to this link