Michael Maskalans wrote:
>
> On 19-May, 2010, at 07:34 , Brian wrote:
>
>> Dodge still uses speed density in all of it's vehicles.
>
> Hmm, I have no idea how the computer would know what the EGR actual vs requested is in a speed density system...
>
> They'd almost have to have a direct measurement of actuation then unless there's something that isn't occurring to me.
>
> Mike
>
most modern EGR systems have an EGR Positon Sensor... not sure exactly
how it works - probably a variable resistor or something that alters the
signal voltage... but its designed to keep the PCM informed on where the
EGR valve is, in relation to where its supposed to be. If it sends a
command to the EGR valve to open to allow more combustion gas into the
engine, (or to close to allow less) and the valve doesn't move, or not
enough, it may set a code.
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