Not getting hot enough doesn't seem consistent with a
plugged cat. They can get cherry red when plugged,I
believe.
Steve P.
--- rws <rwsam2002@yahoo.com> wrote:
>
>
> Steve,
>
> I'm using a mechanical Vacuum Gage on in the Intake
> manifold just below
> the TB air intake unit with MAP, TPS, and IAC mtr.
>
> Here is what I read in the Haynes manual (DAKOTA
> 1987 - 1996) regarding
> their advice for checking a Catalytic Converter:
>
> from chap 6-20
> 4. Although catalytic converters don't break too
> often, they do become
> plugged. The easiest way to check for a restricted
> converter is to use
> a vacuum gauge to diagnose the effect of a blocked
> exhaust on intake
> vacuum.
> a) Open the throttle until the engine speed is
> about 2000 RPM.
> b) Release the throttle quickly
> c) if there is no restriction, the gauge will drop
> to not more than
> 2"/hg or in more above its normal reading.
> d) if the gauge does not show 5"/hg or more above
> its normal reading,
> or seems to momentarily hover around the highest
> reading for a moment
> before it returns, the exhaust system, or the
> converter, is plugged (or
> an exhaust pipe is bent or dented, or the core
> inside the muffler has
> shifted).
>
> I took temperature reading on the Cat again but
> after driving a longer
> period but not faster than 55 mph ( not driven on
> freeway)
>
> New temperature readings were 310 / 260oF (front /
> back) It's still
> not getting up to that 400-600oF range that
> Magnaflow said was the
> correct operating range. Although it is getting a
> 50oF difference out
> of the 50-100oF range.
>
> I'm going to look at the EGR valve today. NAPA said
> they are currently
> selling @ ~ $115.00 The last one I bought was about
> half that price,
> maybe 3-4 years ago (approx. < 20k miles).
>
> Why do the EGR's cost go up? Are parts sellers
> looking at high
> frequency replacements and increasing the cost? Can
> they be cleaned
> successfully and if so how?
>
> Ron
>
>
> ======================
> Re: Re: Re: Re: 94 Dak 5.2L Cat Converter Air Pump
> or Air Switch Valve?
> From: Steve Preston (steveophonic@yahoo.com)
> Date: Sun Sep 30 2007 - 17:53:37 EDT
>
>
> Just jumping onto this topic,but I think we need to
> know whether you're using a gauge to measure
> vacuum,or
> using the vehicle's map sensor signal. They work
> opposite of each other. Gee whiz,this thread lives
> on
> under a pseudonym.... :)
>
> Thanks!
>
> Steve P.
> --- rws <rwsam2002@yahoo.com> wrote:
>
> >
> > Jon.
> >
> > The Vacuum went up to 23-24"/hg when increasing to
> > 1500-2000 rpm.
> > So,I thought what Bernd said (in another post) was
> > that if what I'm
> > seeing (increased vacuum) there might be a plugged
> > exhaust system,
> > true?
> >
> > Regarding a 'Lab Scope' for automotive
> applications,
> > Autotap is using a
> > USB 2.0 port for their OSB-II Scanner, and it cost
> > $200.-- That's in my
> > price range, but for a PC lab-scope s/w and h/w
> > using my own P4 3.3ghz
> > P4 17" ws laptop.
> >
> > I'll start another thread for Auto Lab Scope for
> PC
> > ...
> >
> >
> >
> >
> >
> >
> >
> >
> > Ron
> >
> >
> >
> >
> >
> >
> >
> > ==================================
> > Re: Re: Re: 94 Dak 5.2L Cat Converter Air Pump or
> > Air Switch Valve?
> > From: jon@dakota-truck.net
> > Date: Fri Sep 28 2007 - 19:06:00 EDT
> >
> >
> > rws <rwsam2002@yahoo.com> wrote:
> >
> > > I did the vacuum test at the intake manifold and
> @
> > idle it's 19"/hg
> > > when I raise the throttle quickly it goes to
> zero,
> > if I raise the
> > idle
> > > to 1500-2000 rpms gradually the vacuum goes up
> > about 4"/hg but in
> > about
> > > 20-30 seconds drops back down to 19"/hg. There
> may
> > be a plugged up
> > > converter that is causing this, right?
> >
> > This sounds normal; at a steady rpm, your vacuum
> > should
> > eventually return to about where it was at idle.
> > When you say the
> > vacuum goes "up", do you mean that the numbers go
> > up, such that there
> > is more vacuum or do you mean that the needle goes
> > up, such that the
> > numbers are actually going down and there is less
> > vacuum? (The proper
> > response to opening the throttle should be the
> > latter.)
> >
> > > This is OT but does a lap top PC Oscilloscope
> > converter or adapter
> > > exist? I was looking at a very nice SW/HW $200
> > OBDII Scanner from
> > > Autotap.com but want it to be useful for OBD 1
> > also. Btw, they have a
> > > great tutorial on Sensors.
> >
> > Yes, they exist but from what I have seen, their
> > sampling rate is
> > slow compared to an actual scope, so they are of
> > limited use,
> > depending on what you are trying to measure. (Most
> > of them that I
> > have seen plug into the paralell port or something
> > along those lines,
> > which is why the sampling rate is rather slow, but
> > if you were to get
> > one with its own dedicated PCI card that might be
> a
> > different story.)
> > Keep in mind that I haven't looked into them over
> > the past several
> > years, so things might be different now; I'm not
> > really up on what
> > might be available. The last time I checked
> though,
> > the PC scopes
> > seemed to be limited to somewhere around 25-40
> Mhz.
> >
> > --
> > -Jon-
> >
> > .- Jon Steiger -- jon@dakota-truck.net or
> > jon@jonsteiger.com -
>
>
>
>
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