P0507 code and how it affects your engine idle rpm
P0507 code refers to high idle disorder which cause your engine rpm to surge and setting this code in your dash panel. When troubleshooting code like this, the best route in fixing this is to check for vacuum leak first. High vacuum leak means more air is coming than fuel in the engine mixture. To compensate, the engine computer will command to inject more fuel causing the high idle and this P0507 code. The common symptoms besides surging are poor gas mileage, hesitation, cutting off and hard long starts after the engine warmed up.
Testing your vacuum leak should be your top priority which you can easily do using either a propane or water bottle sprayed on suspected area like throttle body gasket, intake manifold and egr valve. If this spraying is done at high idle, the rpm should go down as soon as the vacuum leak is sprayed. One great technique used by a lot garages involves removing the dipstick from the dipstick tube and installing a vacuum gage. Also, the pcv valve is removed and pcv hole plugged in the valve cover. With engine running on idle, there must be no vacuum leak. If there is a leak, the engine has an intake manifold gasket leak.
Beware that this P0507 code can be caused by uncontrolled fuel supply. Examples are if the fuel injectors are plugged and defective, this can cause havoc in your fuel mixture. This can be checked by unplugging the injectors one at a time and observe a drop of rpm. When there is no rpm drop, that fuel injector last removed is the culprit. Another method is to check the vacuum hose for the fuel regulator. If remove, the engine rpm should go up otherwise, the fuel regulator itself is a suspect. This can be verified by checking the fuel regulator diaphram for signs of rupture or smell of gas leak.
Therefore, the 2 main issues that could cause this code is an vacuum leak which will cause the computer to compensate or too much uncontrolled fuel which also has the same effect: rich fuel mixture.
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