[urq] "Doesn't Need Distributor Signal"

[Cody Forbes]

It's also possible, Steve, that the ignition rotor is just on the edge  
of it's usefull contact range and with belt slop or whatever is moving  
to where the spark cannot find the correct contact on the cap.

-Cody (mobile)

On Mar 25, 2010, at 2:08 PM, "urq" <urq at pacbell.net> wrote:

> Craig wrote:
>
>
>
>
> Good point, however the urq doesn't need the distriubutor signal  
> after start
> up.
>
>
>
>
> . and you say this because you know that you can pull the cable off  
> the Hall
> Sender while the engine is running (on an urq, 5kT, v8q, ???) and  
> the engine
> doesn't stop running, correct?  Yes, I have done that test too, and  
> have
> been tending to agree .
>
>
>
> . but it is also well known that should the distributor timing get  
> too far
> out relative to the crankshaft the engine will cut out and die . in  
> fact
> this was one of my first findings when I got my urq way back when.   
> Ned
> Ritchie printed this info in a QQ issue when I asked about a 4k RPM  
> cut out
> I had many, many years ago .
>
>
>
> Both these statements can't be true . and I now realize what is  
> missing in
> the first statement.  The Hall Sender has two states, and in some  
> ways you
> can think of it just like a set of points in an older car.  When you  
> remove
> the connector from the Hall Sender it is as though the "points" are  
> open all
> the time, and I agree that in this condition the engine will  
> continue to run
> (I too have run this experiment).  The thing is, if you then  
> simulated the
> points being closed by grounding the Hall sender signal to the ECU the
> engine will stop running.  I have not yet run this experiment, but  
> since I
> know the circuitry on the ECU gates the reference pin signal with  
> the Hall
> Sender signal, the "closed points" will stop the reference mark  
> signal .
> this also explains the second fact.  If the crank to cam timing gets  
> to the
> point where the Hall Window no longer matches up with the reference  
> pulse,
> the "closed points" prevent the reference pulse from getting to the
> computer.
>
>
>
> This mechanism was intended to ensure the ignition was synched to  
> the proper
> TDC mark (which is more important on an engine with an odd number of
> cylinders), but it also provides some protection in cases where the  
> timing
> belt jumps teeth.  Of course it won't help much if the timing belt  
> breaks .
>
>
>
> Steve Buchholz
>
>
>
>
>
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