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931.606.021.00 Pulse sender, flywheel sensor? 1981 924 Turbo
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Matilda  



Joined: 17 Apr 2012
Posts: 30
Location: London, Ontario, CA

PostPosted: Sun May 06, 2012 12:40 am    Post subject: Reply with quote

We were able to get a sensor and it's in route to us now. It was purchased from some outfit in the USA. Because I'm not sure when the sensor is arriving, I 'm determined to know if the DITC box is working.

I set up a function generator and scope to the DITC. Powered up the DITC on the bench and started feeding it a small sine wave, and slowly increased amplitude and frequency to the sensor input. Pins 13/14.

Then I started getting pulses out the igntion control line (pin 3). They were in large groups followed by dead space... and then more would follow. I'm guessing it's not going to run perfectly because the signal I'm feeding it isn't 100% what it would expect, and I'm not giving it that missing tooth gap. I was also getting a signal out the tach line PIN 2.
It was constant, and proportion in frequency.

I took my setup down to the car to see what it would do. With the car back together, and the DITC being fed a signal from my function generator, we hook up a spark gap tester to see what would happen. As soon as I started feeding a signal into the DITC, the spark tester, which is sitting on the distributor, started sparking.

Then we took out the spark tester, and cranked the engine. The car started... but it ran rough simply because of timing. My fungen is pumping out a signal for the DITC, but it won't match TDC. Plus the missing tooth gap, etc....
But the point is, the car was idling..... somewhat

Thats the update.... for now.
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McGyver  



Joined: 24 Feb 2009
Posts: 354
Location: Jelenia Gora - Poland

PostPosted: Sat May 12, 2012 6:50 am    Post subject: Reply with quote

I just coming with big steps to 931 DITC world because my 931 engine come back to car... and now it works So I'm really worried about don't have spare crank sensor. How it going to check that BMW unit or any other... which is still in production. Are you sure it's impossible to get any flywheel sensors from Porsche? Sometimes they sell some hidden parts after some time. But yes... the price could be devastating.
Maybe anyone have some spare for sale... maybe in UK?
_________________
931 82' - 5000km after full engine rebuild

SOLD: 924 81' N/A- with turbo gearbox "dogleg" - great but mysterious car
www.mauser98k.internetdsl.pl - if someone like german rifles (English version avalible)
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Matilda  



Joined: 17 Apr 2012
Posts: 30
Location: London, Ontario, CA

PostPosted: Sun May 13, 2012 12:04 am    Post subject: Reply with quote

McGyver wrote:
Maybe anyone have some spare for sale... maybe in UK?


If I had a working DITC and flywheel sensor, I could determine requirements of the sensor, and pick a universal VRS sensor.

If I had the schematic for the DITC, I could also find a Hall effect sensor that could work as well.
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Matilda  



Joined: 17 Apr 2012
Posts: 30
Location: London, Ontario, CA

PostPosted: Sun May 13, 2012 12:07 am    Post subject: Reply with quote

Also, how does my porsche get a tach signal?
There is no wire at pin #2 of the DITC.
I had a drawing.... but I can't find it now

I'm still waiting for my flywheel sensing to come in.
I'm told it was shipped.
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McGyver  



Joined: 24 Feb 2009
Posts: 354
Location: Jelenia Gora - Poland

PostPosted: Mon May 21, 2012 1:43 am    Post subject: Reply with quote

Something for you:
http://www.ebay.co.uk/itm/Porsche-924-Turbo-Series-2-flywheel-sensor-/190681230737?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item2c657cad91

Like for me too expensive at this time
_________________
931 82' - 5000km after full engine rebuild

SOLD: 924 81' N/A- with turbo gearbox "dogleg" - great but mysterious car
www.mauser98k.internetdsl.pl - if someone like german rifles (English version avalible)
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stevekat  



Joined: 19 Jan 2008
Posts: 718
Location: Los Angeles, CA

PostPosted: Mon Jun 11, 2012 4:18 am    Post subject: Reply with quote

For 71 pounds, that was a good deal. They don't go cheaper, and they are usually not around when you need them. Anyone with a 931 would be well advised to pick one up at that cost for a spare when the time may come, at least until a relatively simple and inexpensive alternative solution arises.
_________________
"Never get out of the boat. Absolutely goddamn right. Unless you are goin' all the way."

Gone to new home: '81 924T, US version, CGT Intercooler, UTCIS-PT, Euro DITC, Greddy Trust MBC, Forged Fuchs Flat Dish 6's, Factory Recaro's.
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john h  



Joined: 06 Nov 2002
Posts: 827
Location: Wellington New Zealand

PostPosted: Fri Jun 15, 2012 3:44 pm    Post subject: Reply with quote

Silly question - was teh car working when you got it. If not don't jump straight for faulty sensor.

I picked up a 931 in the late 80's that didn'tgo and it had been in the shop for a new clutch and they had found flywheel was damaged so it was replaced. When the car was put back together it didn't run.

I brought the car for parts and pulled the engine and when stripping the motor realised the flywheel wasn't the same as the one that had been replaced when my 931 was convereted to run 937 clutch. Swapped flywheel over and reinstalled the engine turned the key and it fired up and ran like a dream. I sold it back to original owner for a slight profit and everyone was happy except the garage who had already paid out to the owner

So maybe someone has been playing and swapped the flywheel over? I can't recall if you can pick up the odd tooth on the "ring gear" by looking down the top inspection opening.Normally the 80 and earlier turbo's had spring clutch centres and the DITC units had rubber centred clutch plates - but this can't normally be seen unless you pop the motor and bell housing. Maybe you could get a boreoscope thing in the inspection plate below the slave cylinder could show what clutch is used
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Remember a Porsche is not just for Christmas,

if you take it to pieces slowly it can provide anguish all year long!
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924GT  



Joined: 14 Jul 2012
Posts: 1
Location: Germany

PostPosted: Sat Jul 14, 2012 10:40 pm    Post subject: Reply with quote

Any update, is the car working again ? I have the same problem and would appreciate your help.

Regards, Achim

Matilda wrote:
Also, how does my porsche get a tach signal?
There is no wire at pin #2 of the DITC.
I had a drawing.... but I can't find it now

I'm still waiting for my flywheel sensing to come in.
I'm told it was shipped.
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Carrera RSR  



Joined: 08 Jan 2010
Posts: 2194
Location: Somerset, UK

PostPosted: Tue Nov 20, 2012 10:14 pm    Post subject: Reply with quote

Anyone know how long since these sensors have been NLA and what price they were when available

Anyone have one for sale and what price?
_________________
1980 931 - forged pistons, Piper cam, K27/26 3257 6.10 hybrid turbo, 951 FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife
Now www.924board.org/viewtopic.php?t=34690
Then www.924board.org/viewtopic.php?t=31252
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peterld  



Joined: 10 Dec 2006
Posts: 834
Location: Noosa Heads QLD Australia

PostPosted: Sat Nov 24, 2012 6:23 pm    Post subject: Reply with quote

So......

Did Matilda get the car going? Was it the sensor?

Did Rasta ever come to any conclusion on the useability of a BMW sensor.

All these questions and no answers!
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80/81 932/8 ROW
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Dutch924-racer  



Joined: 23 Jul 2007
Posts: 1066
Location: The Netherlands

PostPosted: Wed Nov 28, 2012 11:49 pm    Post subject: Reply with quote

sold
_________________
937 trackday car
Series 2 engine
951S turbo and intercooler
937 DITC
Fast road camshaft
Forge recirculation valve + boost controller


Last edited by Dutch924-racer on Sat Dec 08, 2012 2:48 am; edited 1 time in total
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Carrera RSR  



Joined: 08 Jan 2010
Posts: 2194
Location: Somerset, UK

PostPosted: Thu Nov 29, 2012 12:33 am    Post subject: Reply with quote

Dutch924-racer wrote:
I got original sensor for sale if anybody is intrested.


I know someone who needs one and I'm reluctant to sell mine. I can put you in touch via email if you pm me your price and details
_________________
1980 931 - forged pistons, Piper cam, K27/26 3257 6.10 hybrid turbo, 951 FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife
Now www.924board.org/viewtopic.php?t=34690
Then www.924board.org/viewtopic.php?t=31252
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JohanE  



Joined: 28 Dec 2012
Posts: 1
Location: Netherlands

PostPosted: Fri Dec 28, 2012 10:05 pm    Post subject: Reply with quote

Is there any news on the BMW sensor?

I have a 931 from 81 with the same problem, one day the car wouldn't start, no spark, no fuel pump. It turned out the flywheel sensor was broken. First I went to the local Porsche Dealership to get a new one. I heard it was sold out. Then I tried several junkyards and Porsche parts specialists in the Netherlands, also none available. Finally I have been to the Porsche museum in Stuttgart, in the museum is the classics division I talked to a specialist who told me the original manufacturer refused to make the sensors for Porsche. The complete stock at Porsche was bought by a company which charged me a ridiculous amount of money for this sensor. At that time I was not prepared to pay that much for the sensor because it is a standard VR sensor and I was convinced there is a cheaper solution. I found a standard VR sensor with 1 kohm resistance for 40 euro's which unfortunately is 22 mm wide so it doesn't fit. Due to a lack of time the project was frozen for a couple of years.

I have heard there is replacement sensor available in the US, does anybody know about this sensor? In this thread I saw information about the BMW sensors, does anybody know the size of these sensors?
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Johan

'81 931
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McGyver  



Joined: 24 Feb 2009
Posts: 354
Location: Jelenia Gora - Poland

PostPosted: Mon Apr 15, 2013 5:12 am    Post subject: Re: 931.606.021.00 Pulse sender, flywheel sensor? 1981 924 T Reply with quote

Matilda wrote:

On my unit, I'm measuring the following:
pins 13 to 15 0.46 ohms.
pins 13 to 14 8.47 ohms.
pins 14 to 15 8.68 ohms.




That's look that Porsche 81 Service manual had one mistake with showing sensor...
15 is definitely ground
13 to 15 should be higher resistance (regarding to 81 Porsche Service manual)

But it looks:
15 to 13 is first small coil (0,5ohm)
13 to 14 is second bigger coil (8,5ohm)
and 15 to 14 should give booth coils (so about 9 ohms)

If that scheme from manual is correct we will have strange situation... because 15 to 14 will be first coil and 15 to 13 will be second coil and they booth connected in the middle (term 14)... so measuring 13 to 15 should give resistance of booth coils and we have other measurements... which I noticed above.
_________________
931 82' - 5000km after full engine rebuild

SOLD: 924 81' N/A- with turbo gearbox "dogleg" - great but mysterious car
www.mauser98k.internetdsl.pl - if someone like german rifles (English version avalible)
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stevekat  



Joined: 19 Jan 2008
Posts: 718
Location: Los Angeles, CA

PostPosted: Thu Jun 13, 2013 2:40 am    Post subject: Reply with quote

Going to resurrect this old thread for a moment. I am having a similar no start issues that I believe is ignition based on a car that has previously behaved flawlessly.

This was a great thread, but no one circled back to close the circle.

One of my questions is can a DITC sensor read somewhat nominal, 8.5 - 9 ohms on two of combinations of pins, and .05 - 0.7 on the last combination, but none the less have failed?

I have a spare sensor, but would like to avoid a needless effort if possible.
_________________
"Never get out of the boat. Absolutely goddamn right. Unless you are goin' all the way."

Gone to new home: '81 924T, US version, CGT Intercooler, UTCIS-PT, Euro DITC, Greddy Trust MBC, Forged Fuchs Flat Dish 6's, Factory Recaro's.
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