Date: Sun, 15 May 2016 04:44:23 -0400
Reply-To: David Beierl <dbeierl@ATTGLOBAL.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: David Beierl <dbeierl@ATTGLOBAL.NET>
Subject: Re: Miss at idle?
In-Reply-To: <BAY175-W24617CE11A39E5009E6E83C6760@phx.gbl>
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At 01:08 AM 5/15/2016, Steven P Smith wrote:
>How about pulling off a fuel injector connector. I did this recently
>on mine and discovered that the problem (exactly as you describe)
>was an intermittent bad connection inside the connector. Replaced
>the connector with a GoWesty kit and problem went away, hopefully
>for a long time. It had been an intermittent problem for at least
>the last 20 years. No one was able to find it. I was lucky.
I'm leary but I don't see any warnings against it. Disconnecting the
ECU connector is forbidden, but the injector connectors apparently
not. It's an inductive load that will kick (generate a voltage
spike**) if it's disconnected while an injector pulse is in process,
but that's what happens anyway when the pulse ends, unless the driver
has pulse-shaping circuits that give a slow turn-off. Also the
presence of the other three injectors will tend to mitigate the
effect to some extent.
I just replaced the connector on my Temp-II sender, which has been
plaguing me for five years, and previously replaced one of the
injector connectors. I think the Temp-II connection fails far more
often than the sender itself does.
**inductance in a circuit limits the rate of change of current in the
circuit because it causes energy to be stored in magnetic
fields. When you close the circuit current builds up [more] slowly
because of the energy going into expanding the field. When you open
the circuit all that energy comes back as the fields collapse, and
the voltage can briefly rise extremely high in order to maintain
current flow as an arc across the widening gap. This is why
inductive loads are rough on switches. If it's a transistor doing
the switching there's no arc, but a corresponding voltage rise that
can punch holes in the semiconductor. When you see a relay in one of
these circuits with a resistor across the coil, that's one of the
techniques to limit stress on the transistor controlling the
coil. If the relay is switching an inductive load related techniques
may be necessary to prevent contacts welding together as they bounce on open.
Yrs,
d
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