[DML] Re: Fuel pressure & RPM Relay

["Harold McElraft" <hmcelraft@xxxxxxx>]

I believe some are expecting far too much from the technical 
information shared on this forum. Diagnosis from information in 
these messages should be viewed as suggestive rather than 
authoritative and should be applied at the users own risk. As any 
engineer or technician will concur I'm sure, actual problem solving 
can be as much of an art as a science and really requires hands-on.

In any event, the best description about the idle, lambda, and spark 
is, in my opinion, best done by combining the reading of the 
Workshop Manual AND the Technical Information Manual. Reading those 
together gives a fairly complete picture of the workings and theory 
of operation of these systems. Further information can be had from 
the official Bosch manuals on K-Jetronic systems which, last I 
looked some time ago, were still around from Bosch.

Harold McElraft - 3354



--- In dmcnews@xxxxxxxxxxxxxxx, "Matt Spittle" <supermatty@xxxx> 
wrote:
> 
> 
> --- In dmcnews@xxxxxxxxxxxxxxx, "endotex23" <endotex23@xxxx> wrote:
> In this example all the owner had to do is study the diagram to 
> answer his own question.  Learning how is not difficult and basic 
> auto electrical theory is something anyone who wants to work on 
cars 
> should learn. 
> 
> So Greg,
> 
> I studied the diagram to answer my own question, and I wasn't able 
> to; not even with a background in electrical engineering.  
> 
> Part of my original question was if the frequency valve was 
supposed 
> to run while the key was in the ON position.  So I look at the 
> diagram...it looks like the frequency valve is powered by the 
lambda 
> relay, which is powered by the RPM relay.  If this all happens, 
then 
> whether the frequency valve turns on or not is determined by pin 
15 
> of the ECU.  Do you have a schematic for the ECU, because it's not 
> obvious to me what it does? 
> 
> Second, it's also not obvious WHY the RPM relay only should 
activate 
> for "about a second" when the key is on the ON position.  The 
> service manual clearly states that it will, but why?  What 
controls 
> that?  If my frequency valve is buzzing and my fuel pump is 
running 
> when I put the key in the on position for more than a second, 
> perhaps this is a failed component somewhere (capacitor in the RPM 
> relay?)?  Do you have a schematic for the RPM relay?  
> 
> So this is why I asked the list.  Please correct me as to where I 
> should have looked if my "homework effort" was inadequate before 
> posting.  
> 
> thanks,
> 
> Matt
> #1604








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