[T3] MPS calibration

Tue Jan 4 17:13:26 PST 2011

Not screw, its an inverted hex... the screw screws into it... and you want
the screw to move IN it not move IT.

Keith

Top Notch Restorations
topnotch at nycap.rr.com 
http://www.a383ina68.addr.com/radiorest/main.htm
71 Squareback "Hothe"
65 Notchback "El Baja Rojo"
65 Squareback "Eggcrate"
87 golf "Winterat"
93 RX7 "Redstur"

-----Original Message-----
From: type3-vwtype3.org-bounces at lists.vwtype3.org
[mailto:type3-vwtype3.org-bounces at lists.vwtype3.org] On Behalf Of Bryon
Garvin
Sent: Tuesday, January 04, 2011 4:39 PM
To: type3 at vwtype3.org
Subject: Re: [T3] MPS calibration

Is the inner screw the one you should not touch?
I'm not doing this procedure, I was just curious.

 - Bryon

On Sun, Jan 2, 2011 at 3:21 PM, Keith Park <topnotch at nycap.rr.com> wrote:

> Ahh... well, now you have touched that inner stop adjustment your totally
> Boned.
>
> First off, you cant really adjust these with inductance reading except to
> get in the ball park, and you NEVER want to touch that inner stop
> adjustment
> as its made for a particular unit to keep your car from spiking too lean
> under certain light throttle conditions because If you do you can burn up
> the engine on the highway. 1/16 turn makes the difference between right
and
> spiking too lean....
>
> You start by prepping the unit for adjustment and that means epoxying the
> inner stop adjustment in place so you can adjust the main mixture without
> touching the inner stop adjustment.  You must also realize that that cap
> screw is actually an outer stop adjustment for full throttle enrichment
and
> is CRITICAL for the longevity of the diaphragm and engine.
>
> The only way to truly get it right is mount a wideband O2 sensor in the
> correct location (right side end of muffler)and start the process... get
> the
> main mixture right, then make sure the inner stop doesn't let you lean out
> more than say 15 or so, then the outer adjustment and yes, they all
> interact
> with each other and it's a long process and totally dependant  on
> everything
> else in the system being in PERFECT condition.
>
> I have the adjustment dimensions for a stock 007 miked out, they will get
> you started, but you need the AFR meter to get it right and yes, you can
be
> wrong and everything will seem fine till you have a hole in #3 on a hot
day
> pulling a long hill.
>
> I went thru all this on setting up my 2056 and when I put the stock motor
> back in I was amazed at how much better I could get it running by tweaking
> out the stock pressure sensor with that AFR in place.
>
> There is a PhD stickey on this on the Samba, read thru it all... its
really
> enlightening.
>
> Keith
>
>
> Top Notch Restorations
> topnotch at nycap.rr.com
> http://www.a383ina68.addr.com/radiorest/main.htm
> 71 Squareback "Hothe"
> 65 Notchback "El Baja Rojo"
> 65 Squareback "Eggcrate"
> 87 golf "Winterat"
> 93 RX7 "Redstur"
>
>
> -----Original Message-----
> From: type3-vwtype3.org-bounces at lists.vwtype3.org
> [mailto:type3-vwtype3.org-bounces at lists.vwtype3.org] On Behalf Of Bryon
> Garvin
> Sent: Sunday, January 02, 2011 4:04 PM
> To: type3 at vwtype3.org
> Subject: Re: [T3] MPS calibration
>
> Hi all -
>
> Well my friend showed up today to take the inductance readings from my PS
> and then attempted to adjust his so that they match.  His '71 Fastback
> MT/FI
> has not been running all that well.  It died on a long trip and a pressure
> sensor from a late 60's model was installed at a shop and got him running
> again....but not great.  He limped home and has been trying to figure it
> all
> out ever since.  Because the "C" sensor would no longer run his car, and
> the
> one the shop put in did allow him to drive, he started by looking at the
> sensor.
>
> He came today and we pulled MY working sensor (we both have 71 Fastbacks
> MT/FI).  First thing we did was use an inductance meter to measure the
> values on both inner and outer pins at zero vacuum.  We then used a hand
> vacuum pump to take readings again at 4 inHg and 15 inHg.  We were
> following
> the instructions on this site:
>
>
>
http://members.rennlist.com/pbanders/manifold_pressure_sensor.htm#Adjustment
> s
>
> We then took HIS sensor and removed the screw.  With me holding the
> inductance meter probes on the pins, he turned the inner and outer screws
> and made the values match what my PS readings were.  When we were done,
his
> values were exactly like mine.  It took some time as each screw affected
> the
> other and we had to go back and forth.  This brings me to something Jim
> said
> one time and I wanted to ask you, Jim, what you meant:
>
> ".... the 3 adjustments will have to be done in some particular order to
> work.
> The problem is that the adjustments affect each other, so I need a
> proceedure that gets it right in a finite amount of time."
>
> Now that I have tried to do this, why does it all have to happen in a
> finite
> amount of time?  I don't understand that.  Can you elaborate?
>
> We put the sensor in his car, and well....it didn't run the car.  It
barely
> started and it sure didn't idle.  So he went home with the newly "tuned"
> sensor in his hand wondering why it all didn't work.  I'm no help!  I was
> just watching and helping take readings.  So, he's kind of back to square
> one.
>
> But I did want to post our procedure and results for anyone that was
> interested.  And Jim I'd love to hear your thoughts on what we did and why
> it didn't seem to work.
>
> One other note of interest....I have 3 "C" sensors that are on my shelf.
>  Since Larry was here with his measuring equipment I figured I'd put them
> thru the tests and see what the values were.  Months ago, they all seemed
> to
> hold vacuum when I sucked on them with a new piece of hose.  One of them
> clearly was worse-off than I thought.  With a hand pump, we applied 15
inHg
> and it slowly dropped in a matter of 8-10 seconds back to zero.  But the
> other two held strong.
>
> Out of the 2 that DID hold vacuum, one had inductance values nearly
> identical to the values of the working sensor in my car.  The 2nd one had
> values that were nearly HALF of what the unit in the car read.  So, what
> does this mean?  I have no idea :)
>
> Anyway, our findings are in this spreadsheet if anyone wants to take a
> look:
>
>
>
>
https://spreadsheets.google.com/ccc?key=0AmRobzkiJkYhdGx1aVF3TXpHV2xoaEVFS21
> oZlZpSnc&hl=en&authkey=CJucx48O
>
> Thanks,
>
>  - Bryon, '71 Fastback
>
>
> On Tue, Dec 28, 2010 at 8:01 PM, Bryon Garvin
> <spinningrooves at gmail.com>wrote:
>
> > Hi all -
> >
> > I'm trying to help a friend who wants to attempt calibrating his MPS.
He
> > believes that his needs adjusting even though it holds vacuum.  He is
> > consulting this website:
>
>
http://members.rennlist.com/pbanders/manifold_pressure_sensor.htm#Calibratio
> n
> >
> Curves<
> http://members.rennlist.com/pbanders/manifold_pressure_sensor.htm#Cal
> ibration+Curves>
> >
> > He's got a 71 sensor (Bosch 0 280 100 007) which is not listed here and
> I'm
> > asking to see if anyone happens to have the data for this sensor, like
is
> > listed below in the table, so that he can do the 0 in.Hg, 4 in.Hg, and
15
> > in.Hg measurements and make calibration adjustments.
> >
> > He lives an hour away and would like to come take the measurements from
> my
> > sensor since I have the same one...but if this data is out there, it
> would
> > be a lot easier to just get him the information.  Additionally, who is
to
> > say that my sensor is even going to still be "spec"?
> >
> > Below is the table, I hope that it comes thru the email looking correct.
> >  If not, it's in the link above if you scroll down to "Calibration
Values
> > Table".
> >
> > Any help greatly appreciated.  And I believe he is still on this list
> (not
> > totally sure) so he might even see the replies, otherwise I will get the
> > info to him.
> >
> > Thanks very much for any help,
> >
> >  - Bryon, '71 Fastback
> >
> > Calibration Values Table
> >
> > *Bosch p/n*
> > *0 280 100 027**0 280 100 037**0 280 100 043* *0 280 100 049*
> >
> > *Application*
> > Not sure 1973 2.0L 9141974-1976 2.0L 9141970-1973 1.7L 914
> >
> > *Sampling*
> > based on 1 good OEM non-rebuilt unit based on 1 rebuilt unitbased on 2
> > rebuilt and 1 good OEM non-rebuilt unitsbased on 1 NOS unit *Vacuum
> Level*
> >      0 in. Hg1.32 H 1.44 H1.39 H1.34 H4 in. Hg 1.17 H1.26 H1.18 H 1.15
> H15
> > in. Hg0.72 H0.72 H 0.71 H0.71 H
> >
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