EGR Corrections

[Bruce Plecan]

-----Original Message-----
From: Terry <thartman at gte.net>
To: diy_efi at efi332.eng.ohio-state.edu <diy_efi at efi332.eng.ohio-state.edu>
Date: Sunday, July 26, 1998 2:09 PM
Subject: Re: EGR Corrections


>Bruce Plecan wrote:
>
>> Does the Diacom show the burst knock activity?.  
>>
>I'm not sure what your term busrt knock activity is referring to.
>
>>  Does it show the EGR timing addition?.
>
>No - not this just by itself.
>
>> Becomes a matter of what they call requested timing.
>
>What Diacom displays for my ECM is Spark Advance Relative to TDC
>which is the total spark advance applied to the engine's ignition
>system by the ECM.  The spark advance value is relative to Top Dead
>Center and is is displayed in degrees. 
>
>It also shows Spark Advance Relative to Reference which is the amount
>of spark advance that is being applied to the HEI module by the ECM. 
>The spark advance valve is relative to the reference pulses received
>from the distibutor and my be added to the base timing to obtain the
>total advance.
>
>Diacom shows the Spark Control Counts which is just a counter from 0-255
>that will just roll over to zero after the upper limit is reached.
>
>As far as EGR info, Diacom displays EGR Duty Cycle which is a the 
>percentage of the EGR solenoid ON time vs OFF time.   On my
>car, the EGR valve is controlled by the EGR Solenoid which in
>turn is controlled by the ECM.  When the EGR Solenoid is de-energized
>it allows engine vacuum pressure to operate the EGR valve.
> 
> 
>> > This would indeed be a bad thing as that
>> >would also imply that the data from the ECM diagnostics would be
>> inaccurate....
>> 
>> How would you figure that???
>
>By the way you presented your original statement.  My question was really
>whether the Diacom would show the total timing - and I think
>that it does.  
>
>>  Diagnostics is for fault finding, 
>
>I disagree.  I find that Diacoms' diagnostics are a good tool for
>tuning...
>
>> if it's intended to operate a certain way, then there is no error.
>
>This is true!  But "indended operation" is what I think we
>are trying to discover here.
>
>T.
>