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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