Great info guys, thanks.
I will find out a bit more about the Explorer, thought it was a mid 80's,
but I'll check.
sc
"Jim Warman" <mechanic@[EMAIL PROTECTED]
> wrote in message
news:0XsTj.469$Yp.100@[EMAIL PROTECTED]
> The "negative feedback" term is with the way the EGR valve operates
> internally... this http://tinyurl.com/5ehap9
probably explains it better
> than I can (with pictures added for clarity, no less 8^) ). The feedback
I
> am referring to isn't feedback on valve position to the PCM.
>
> The OP didn't say ground electrode but did mention the "element"... I
may
> be wrong, but I am assuming that this is the centre electrode he is
> referring to... At the same time, it is common for some erosion to occur
on
> the ground electrode, especially on plugs at or beyond their expected
> service life... And we must also consider what motors are fitted with a
> wasted spark system... The "ground" electrode will suffer more erosion
than
> the centre electrode on the negative side plugs. But here is where
careful
> inspection is required... Is the electrode eroded or is it melted away?
>
> Erosion can occur from oxidation, corrosion, fuel quality (perhaps even
fuel
> additives) or even the metallurgy of the plug itself. A spark plug with
a
> burned away electrode could be because of pre-ignition, detonation or
faulty
> EGR operation. or any other cir***stances that keep the spark plug
hotter
> than intended.
>
> Remember, the spark event typically lasts for 1.5 milliseconds (most COP
> systems are now "multi-striking" at idle)... during this time, the spark
> plug is at it's hottest and, depending on the system, one electrode or
the
> other is being bombarded by a stream of electrons... and this can create
the
> condition...
>
> HTH.
>
>
> "Happy Traveler" <happy_traveler@[EMAIL PROTECTED]
> wrote in message
> news:4MmdnXrciJmYo4PVnZ2dnUVZ_gWdnZ2d@[EMAIL PROTECTED]
> > Hi Jim,
> >
> > Thanks for the compliments!
> >
> > A couple comments:
> > 1) I still have one of those mid-80 Fords (to be donated to a
> > not-so-well-off friend, as soon as I can replace the worn control arm
> > bu****ngs). The EGR is not a negative feedback type, but uses a
position
> > sensor - a potentiometer mounted on the top.
> > 2) In my humble experience of repairing my own vehicles for the last
30+
> > years, I have never seen a ground electrode that's totally burned -
not
> > even close. So what else would cause such thing?
> >
> >
============================================================================
=================
> >
> > "Jim Warman" <mechanic@[EMAIL PROTECTED]
> wrote in message
> > news:mb9Tj.251$Yp.126@[EMAIL PROTECTED]
> >> HT, you have a very good grasp on the subject of pre-ignition... A
gold
> >> star for you 8^)
> >>
> >>
> >> For the OP.... it is normal for spark plug electrodes to suffer from
> >> erosion... Pre-ignition will tend to leave deposits on the ground
> >> electrode if it is severe or has been left unattended for any length
of
> >> time...
> >> If this vehicle is, indeed, a 1986.... IIRC, Ford used a "negative
> >> feedback" type EGR valve... There is a small ****t inside the valve
that
> >> can carbon over and this would have the effect of having the car
"nose
> >> over" on light acceleration...>
> >
> >
>
>
|
