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I Can't See All My Gauges!
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9XX Girl!  



Joined: 20 Sep 2009
Posts: 1617
Location: Cornish Riviera SW England

PostPosted: Sat Sep 26, 2009 9:26 am    Post subject: Reply with quote

PORSCHEV

Quote:
I haven't met a chick in MY LIFE that knew anything about a car.

Remind me never to go to Cedar Lake Nova Scotia, Canada

Question: do you let women vote in Canada

Question 2: would you consider voting for a female Prime Minister

Question 3:Who is the head of state in Canada?

If you think i am Rasta, cast your vote now http://www.924board.org/viewtopic.php?t=30398
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924 (84) N/A 2 ltr - 5 Speed - BLACK - Project (looking for 200BHP, any ideas!)
924 (81) N/A 2 ltr - 3 Speed Auto - SURINAM RED (Metallic) - Near Original Spec (sticking with originality)
BOTH ON THE ROAD, BOTH USED EVERY-OTHER DAY
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PORSCHEV  



Joined: 02 Nov 2002
Posts: 1911
Location: Cedar Lake Nova Scotia, Canada

PostPosted: Sat Sep 26, 2009 10:23 pm    Post subject: Reply with quote

We let women vote one year in Canada and they voted in a woman...Kim Campbell. She was in office for a few months and then was voted out. Our country has been in turmoil ever since. Now women are in the kitchen on a full time basis.
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1976 924
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1978-#53 "D" track racer.
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9XX Girl!  



Joined: 20 Sep 2009
Posts: 1617
Location: Cornish Riviera SW England

PostPosted: Sat Sep 26, 2009 10:37 pm    Post subject: Reply with quote

We had Mrs Thatcher but she only lasted 18 years. And as for Queen Lizzy-bet II - Lady Diana Spencer ....Well you are missing out, you should let them in the garage too. Look whet you are missing out on

http://www.924board.org/viewtopic.php?t=30398&postdays=0&postorder=asc&start=30

Check out the page 3 photos. Built by women.
Thats what i call girl power.
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924 (84) N/A 2 ltr - 5 Speed - BLACK - Project (looking for 200BHP, any ideas!)
924 (81) N/A 2 ltr - 3 Speed Auto - SURINAM RED (Metallic) - Near Original Spec (sticking with originality)
BOTH ON THE ROAD, BOTH USED EVERY-OTHER DAY
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9XX Girl!  



Joined: 20 Sep 2009
Posts: 1617
Location: Cornish Riviera SW England

PostPosted: Mon Sep 28, 2009 2:23 am    Post subject: Reply with quote

We seem to have on off topic a bit!

Anyway, does anyone know where i can get one of these?



Smiths vacuum fuel consumption gauge - Smiths part no. is VL2301-00

i will try see if the gubbings can be fitted into this



The needle will zero at the wrong end of the scale but it looks like it would deflect the correct amount of degrees

if the gubbings will go in.

has anyone taken these rev counters apart? and any pics?

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924 (84) N/A 2 ltr - 5 Speed - BLACK - Project (looking for 200BHP, any ideas!)
924 (81) N/A 2 ltr - 3 Speed Auto - SURINAM RED (Metallic) - Near Original Spec (sticking with originality)
BOTH ON THE ROAD, BOTH USED EVERY-OTHER DAY
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RC  



Joined: 25 Mar 2007
Posts: 2523
Location: Coffs Harbour, Australia

PostPosted: Mon Sep 28, 2009 3:28 am    Post subject: Re: I Can't See All My Gauges! Reply with quote

9XX Girl! wrote:
Hi All

l, I'm new to this forum and i don't see many women here so please go easy on me.

Now this clock has extra pins on the back as it also incorporates a "econometer"! (an naturally i want this to work). I can imagen the responce right now "mad woman - 924 N/A is mechanica fuel injection so can't be done!"
But i do like a chalange.

I can sort the rev counter bit.
i.e.
unmarked pin = (-) ground
pin 2 = +12v feed (ignition switched from radio relay)
pin 6 = pin 1 of coil

see... (part 4 page 2)
http://www.pelicanparts.com/944/electrical/944_electrical_diagrams.htm

It's the "econometer" marked in MPG that I need to know more about.
This appears to make its calculation via the 4 square wave pulses that come from the Hall Effect Transducer on the back of the speedo (or should i say odometer), and blend "other info" with it, to display Miles Per Gallon. Luckily my speedo (being an 84 924) has a Hall Effect Transducer on the back. Just needs connecting to pins "HG" and "H+" of tacho/econometer.

Now the "other info" bit! Some of that info will be revs (but that is done internally so no worry there!)

pin 4 of the tacho/econometer gets info from the coolent temp sensor (so no worry there, just link a wire from back of temp gauge)

pin 1 of the tacho/econometer is a different story. On thre 944 it gets a signal from pin 11 of the ECU. Considering the tacho/econometer is coping with Mathematics in an electronically jiggery pokery sort of fashion. This might be (at a guess) a +5v TTL supply???? Any info would help!

pin 5 of the tacho/econometer - this little puppy gets pulses from the injectors. OK easy on the 944 cos it has electronic fuel injection.
924 N/A has mechanical K-Jetronic (nice) so... i need to make a way of getting some "injector like" pulses up to pin 5.

Any ideas welcome. I was thinking along the lines of the way the D-Jetronic worked in the 1960s Porsche 914 "Speed-Density" Fuel Injection system.

Other D-Jetronic Cars

Early Merc. 280E
Early Merc. 300
Early Merc. 450/450E
Porsche 914E
SAAB 99 EMS
Volvo 1800E, 164E
VeeDub Types 3, early 4.

D-Jetronic uses a simple Vacuum pressure sensor to calculate correct injector pulses from the changes in inlet manifold pressure. After all, this is how the timing is avanced and retarded during acceleration at the dizzy.

I was thinking of using a "pre ignition vacuum sensor" or MAP sensor such as a 19204S found on modern cars such as
VAUXHALL / ALFA ROMEO / VOLVO / GM / CITROEN / RENAULT / KIA / HYUNDAI. These sensors can be found on eBay for only a few English Pounds. (Cheep as Chips!)

http://cgi.ebay.co.uk/RENAULT-MAP-SENSORS-GM-TYPE-BARGAINS_W0QQitemZ180407508563QQcmdZViewItemQQptZUK_CarsParts_Vehicles_CarParts_SM?hash=item2a01201e53&_trksid=p3286.c0.m14

It will fix to the bulkhead in the engine bay and get a vacuum feed from a "T-fitting" that i will splice into the existing pipe between the Throttle Body and the Dizzy.

The sensor listed above has three pins. (don't have pin out-data yet)
Supply Voltage 5.0 +/-0.5 VDC
Ground (-)
Output Voltage 0.25 to 4.85 VDC (5VDC at full excitation)

So any ideas and info are welcome as to how i will turn this signal into injector pulses to drive my eco-gauge.

Thanks muchley

Paula


Hi Paula, (or Paul, or James, or Tom, or Dick, or whoever). It`s good to have some stimulating conversation and even some action around this board. Bored with the usual noobs that start off with "my 924 has trouble starting when warm" or "I`m gonna shave the head and fit a K&N filter and blow off 12 sec Hondas". If you actually are a chick, thats a real bonus as you can shame many guys around here.

Perhaps you`re having so much entertainment you don`t really want to get this thread back on topic?
It`s quite an interesting and difficult question you pose here. We`ve had the typical lazy & simple US responses. Surprised that no-one has suggested fitting a simple vacuum gauge yet.

As you correctly deduce the input from #11 on the DME is the critical signal to this econogauge`s operation. The easiest and preferable option is to scope this signal and see what it really looks like, shape, amplitude, frequency and duty cycle. Then see how it changes with engine variables. My guess is a square wave following the injector open pulse width. Very likely a nom 5V TTL as suggested but with Bosch or Porsche may just as easily be a variable analogue voltage.

This is the schematic of the 951 DME which is larger and clearer than the 944 circuit:




And the 911/944 circuits:



DME connector pin #11 feeds from pin #3 on IC S400 0127. So WTF is that? Google doesn`t help here, but leads to the Pelican boys who don`t know either:
http://forums.pelicanparts.com/porsche-911-technical-forum/327832-alternative-fuel-injectors-8.html#post3751656

Maybe some info in that thread though. That IC doesn`t appear to be a generic type 74 series 127 either but possibly something similar.

Your idea of a MAP sensor may work. It is relatively easy to use a varying voltage or resistance to control the frequency or duty cycle of a square wave pulse generator. Am happy to give some circuit design ideas. As the 944/ 924S used an analog AFM perhaps that would give a more direct correlation to fuel flow. Easy to fit and adapt the output to a varying square wave. IF in fact that is what this econometer requires.

A lot of work for little benefit IMO but like a challenge too. Have you considered fitting EFI and getting more benefits than a correctly modulated output signal to drive the MPG meter?
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9XX Girl!  



Joined: 20 Sep 2009
Posts: 1617
Location: Cornish Riviera SW England

PostPosted: Mon Sep 28, 2009 4:30 am    Post subject: Reply with quote

RC You have been busy.

According to the UK Radio Spares Catalogue
IC S400 0127 is a 12 Bit A to D converter.

http://uk.rs-online.com/web/search/searchBrowseAction.html?method=retrieveTfg&binCount=1&Ne=4294957561&Ntt=IC+S400+0127&Ntk=I18NAll&Nr=AND%28avl%3auk%2csearchDiscon_uk%3aN%29&Ntx=mode%2bmatchallpartial&N=4294955315&Nty=1

Click here for the DATA SHEET http://docs-europe.origin.electrocomponents.com/webdocs/04fd/0900766b804fdf5b.pdf

I need to do some reading but pin 3 of this IC seems to be Chip Select. Active low logic input. This input provides the dual function of initiating conversions on the chip. Also frames the serial data transfer.

Quote:

The easiest and preferable option is to scope this signal and see what it really looks like, shape, amplitude, frequency and duty cycle.


Do you have a 944 and a battery powered scope or Ö.a mains scope and a dyno would do?

Let me do some reading (Iím trying to cook sausages in batter at the mo) and I will get back. Thanks and hope these links make sence.
_________________
924 (84) N/A 2 ltr - 5 Speed - BLACK - Project (looking for 200BHP, any ideas!)
924 (81) N/A 2 ltr - 3 Speed Auto - SURINAM RED (Metallic) - Near Original Spec (sticking with originality)
BOTH ON THE ROAD, BOTH USED EVERY-OTHER DAY
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v8carreragts  



Joined: 05 Sep 2003
Posts: 591
Location: Wheaton, IL

PostPosted: Mon Sep 28, 2009 6:48 am    Post subject: Reply with quote

Here is a picture of inside the tach, the small metal can is the MPG gauge.

[img][/img]

as for the signal, all you need to do is just look into the factory manual. It tells you what the signal is. (volume 4 pg. 90-2)

The hall sensor in the speedo gives a square wave 4 pulses per tire revolution. Less than on volt to over 6 volts. Termals 5 and H+ have ign on 12v. HG is the pulsed signal.

I will be using this (mulitplied) for the VSS for the injection on my v8.
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9XX Girl!  



Joined: 20 Sep 2009
Posts: 1617
Location: Cornish Riviera SW England

PostPosted: Mon Sep 28, 2009 6:55 am    Post subject: Reply with quote



Ok this is what i think is happening here






The tacho/econoguage gets a signal (pin 5) from the injectors in order to make its reading.

pin 1 of tacho/econoguage sends a signal to pin 11 of the ECU which is connected to pin 3 of IC S400 0127 (12 bit A to D converter).

This signal is a closed loop feedback system as it is dependent on injector frequency, road speed (via hall transducer),
coolant temp and coil pulses, resulting in the ECU making
small changes to the injector signal.
(see above diag)

In other words pin 11 of the ECU is sampling the falling edge of
the analog output of the tacho/econogauge which is a sum of
injector pulse frequency, road speed, coolant temp and coil pulses.
(Whatever that looks like but it will include a lagging power factor because all are inductors exept temp which is resistive)
IC S400 0127 is converting this analogue signal into a digital signal that will easily (and safely) interface with microprocessors.
Donít forget, fuel injectors, hall effect transducer and ignition coil
are inductive devices so there will be plenty back EMF inherent in
the system that you donít really want the microprocessors to see.

I just need to simulate injector pulses that are inversely proportional
to vacuum and fire it up pin 5 of the tacho/econoguage and forget
about tacho pin 1 that feeds ECU pin 11.

Quote:
Have you considered fitting EFI


er why fix what is not broken. When the K-Jetronics fails and it is
beyond economical repair I will have to give it a go.

But realistically, the K-Jetronic may out-live the engine and
I end up replacing it all with some sort of hydrogen cell in
another 25 years.

Plus, I'm not really into electronics. I like mechanical stuff!
_________________
924 (84) N/A 2 ltr - 5 Speed - BLACK - Project (looking for 200BHP, any ideas!)
924 (81) N/A 2 ltr - 3 Speed Auto - SURINAM RED (Metallic) - Near Original Spec (sticking with originality)
BOTH ON THE ROAD, BOTH USED EVERY-OTHER DAY


Last edited by 9XX Girl! on Mon Sep 28, 2009 7:38 am; edited 4 times in total
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9XX Girl!  



Joined: 20 Sep 2009
Posts: 1617
Location: Cornish Riviera SW England

PostPosted: Mon Sep 28, 2009 7:07 am    Post subject: Reply with quote

Thanks v8carreragts that does help.
I could get the gubbings of a 52mm Vacuum gauge in there which is one way of doing it.

It is not as easy as you say with my set up.
as well as a connection from the hall effect transducer to pin 5
you need a feed from the injectors as the gauge need to know
how much fuel is being used.
Easy with EFI but not so with my mehanical K-jetronic 924 N/A

See diag above.

This is why 924 tachos only have 3 wire
and 944 tachos have 6 wire
_________________
924 (84) N/A 2 ltr - 5 Speed - BLACK - Project (looking for 200BHP, any ideas!)
924 (81) N/A 2 ltr - 3 Speed Auto - SURINAM RED (Metallic) - Near Original Spec (sticking with originality)
BOTH ON THE ROAD, BOTH USED EVERY-OTHER DAY
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9XX Girl!  



Joined: 20 Sep 2009
Posts: 1617
Location: Cornish Riviera SW England

PostPosted: Mon Sep 28, 2009 7:23 am    Post subject: Reply with quote

The smiths vacuum gauge i was looking at went for over £70 inc postage
on ebay just!

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=320425426562&ssPageName=STRK:MEWAX:IT

looks like its gonabe a home made
vacuum dependent injector frequency generator then

my head is hurting now!
_________________
924 (84) N/A 2 ltr - 5 Speed - BLACK - Project (looking for 200BHP, any ideas!)
924 (81) N/A 2 ltr - 3 Speed Auto - SURINAM RED (Metallic) - Near Original Spec (sticking with originality)
BOTH ON THE ROAD, BOTH USED EVERY-OTHER DAY
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RC  



Joined: 25 Mar 2007
Posts: 2523
Location: Coffs Harbour, Australia

PostPosted: Mon Sep 28, 2009 1:10 pm    Post subject: Reply with quote

9XX Girl! wrote:
RC You have been busy.

According to the UK Radio Spares Catalogue
IC S400 0127 is a 12 Bit A to D converter.

http://uk.rs-online.com/web/search/searchBrowseAction.html?method=retrieveTfg&binCount=1&Ne=4294957561&Ntt=IC+S400+0127&Ntk=I18NAll&Nr=AND%28avl%3auk%2csearchDiscon_uk%3aN%29&Ntx=mode%2bmatchallpartial&N=4294955315&Nty=1

Click here for the DATA SHEET http://docs-europe.origin.electrocomponents.com/webdocs/04fd/0900766b804fdf5b.pdf

I need to do some reading but pin 3 of this IC seems to be Chip Select. Active low logic input. This input provides the dual function of initiating conversions on the chip. Also frames the serial data transfer.


Not sure how you got onto that IC but its not the right one. Its not an ADC or even a DAC. My guess is a pulse shaper or a custom injector driver/ current limiter as proposed by the Pelican guys. 944 & 951 injectors are low (mid) impedance peak & hold type. Also IC S400 is a 14 pin DIP.



Must have been more tired than I thought last night since I overlooked that S400 is the component identifier, S being IC`s (what`s IC in german?) See how the 5V reg is S300 and the op amp(s) are S800\A, S800\B, ......... Regardless, still can`t find any info on XX0127. Nor can the Pelican guys:

http://forums.pelicanparts.com/porsche-911-technical-forum/398595-calling-motronic-experts-ic-information.html

Quote:

Quote:

The easiest and preferable option is to scope this signal and see what it really looks like, shape, amplitude, frequency and duty cycle.


Do you have a 944 and a battery powered scope or Ö.a mains scope and a dyno would do?


Have a few scopes, hand held & mains, but no 944 or a DME. And only wish there was a dyno in the garage. Perhaps if you have access to a function or squarewave generator it may be interesting to feed in a max 5V PP signal to meter pin #1 (as from DME pin #11)

Quote:
The tacho/econoguage gets a signal (pin 5) from the injectors in order to make its reading.

pin 1 of tacho/econoguage sends a signal to pin 11 of the ECU which is connected to pin 3 of IC S400 0127 (12 bit A to D converter).

This signal is a closed loop feedback system as it is dependent on injector frequency, road speed (via hall transducer),
coolant temp and coil pulses, resulting in the ECU making
small changes to the injector signal.
(see above diag)

In other words pin 11 of the ECU is sampling the falling edge of
the analog output of the tacho/econogauge which is a sum of
injector pulse frequency, road speed, coolant temp and coil pulses.
(Whatever that looks like but it will include a lagging power factor because all are inductors exept temp which is resistive)
IC S400 0127 is converting this analogue signal into a digital signal that will easily (and safely) interface with microprocessors.
Donít forget, fuel injectors, hall effect transducer and ignition coil
are inductive devices so there will be plenty back EMF inherent in
the system that you donít really want the microprocessors to see.

I just need to simulate injector pulses that are inversely proportional
to vacuum and fire it up pin 5 of the tacho/econoguage and forget
about tacho pin 1 that feeds ECU pin 11.


Sorry, but I disagree with that hypothesis. The "signal" at meter pin #5 is DC, fed via B on the injector B+ line and switched through the FPR. Remember the DME is earthing the injectors to fire, via T402 darlington driver.

The ignition signal is not fed to the DME but rather from it via D on pin #1. The DME also controls the ignition timing and the dwell. Running 2.5mm2 wire from DME pin #1 to the coil - the DME is earthing the coil to fire. See here:



So I still believe a signal from DME #11 is required and that it is proportional to the injector pulsewidth. A MAP signal will give a reasonable approximation of fuel injector flow, an AFM signal will be more accurate. However from others opinions the MPG gauge is inaccurate and vague anyway. Either will require a modulated pulse signal and will involve some electronics.

Quote:
Iím trying to cook sausages in batter at the mo


That helps explain how you get so fat.
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9XX Girl!  



Joined: 20 Sep 2009
Posts: 1617
Location: Cornish Riviera SW England

PostPosted: Wed Sep 30, 2009 9:57 am    Post subject: Reply with quote

I am now the proud owner of a yellow 944 Speedo, rev counter and, temp / fuel warning light cluster.

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=220484446444&ssPageName=STRK:MEWAX:IT

will fit all three when they arrive and then the work will start getting the econometer working.

Plan is to send a range a bunch of different signals up pin 1 with a signal generator to find out what type of signal
gets the econogauge working, then build a vacuum powered device to feed the econometer those signals

Found some signal geny software http://www.nch.com.au/tonegen/index.html

So i will be using an old laptop to fire it up.

Watch this space
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924 (84) N/A 2 ltr - 5 Speed - BLACK - Project (looking for 200BHP, any ideas!)
924 (81) N/A 2 ltr - 3 Speed Auto - SURINAM RED (Metallic) - Near Original Spec (sticking with originality)
BOTH ON THE ROAD, BOTH USED EVERY-OTHER DAY
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Jakkq  



Joined: 29 Sep 2008
Posts: 807
Location: Norfolk, Nebraska

PostPosted: Fri Oct 02, 2009 7:12 am    Post subject: Reply with quote

RC wrote:




Are these the blueprints to the Gaza Prison?
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9XX Girl!  



Joined: 20 Sep 2009
Posts: 1617
Location: Cornish Riviera SW England

PostPosted: Fri Oct 02, 2009 7:22 am    Post subject: Reply with quote

I'll give you Gaza prison - Cougar bait!
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924 (84) N/A 2 ltr - 5 Speed - BLACK - Project (looking for 200BHP, any ideas!)
924 (81) N/A 2 ltr - 3 Speed Auto - SURINAM RED (Metallic) - Near Original Spec (sticking with originality)
BOTH ON THE ROAD, BOTH USED EVERY-OTHER DAY
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Rich H  



Joined: 10 Jun 2007
Posts: 2665
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PostPosted: Fri Oct 02, 2009 7:36 am    Post subject: Reply with quote

I got very lost trying to trace the gauge wiring on VDO gauges, they seem to be boards for every gauge in one board and wire in the bits they need.
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