ideola

For some time, us 931 S2 guys have been hampered with failing crank reference sensors, which are NLA from Porsche. We've been doing some digging over on 924board, and a couple of astute guys there noticed that the 944 and 928 "timing mark senders" as they're called in PET have the same sensor, albeit with a shorter lead. After doing some searching in PET, what I've learned is that the part number is 911.606.108.00, and was used on all 928s from 1984-88 and all 944s from 1984-onward.

Unfortunately, the 928/944 part is also NLA.

What are you guys doing when your crank sensors fail? If it's not a problem for you now, it soon will be. Maybe we need to pool our collective efforts to find a way to get these back on the market? Thoughts?

hacker-pschorr

Bosch part #0 261 210 002

Also found in a few BMW's

ideola

Thanks for the quick reply. However, I don't think that's the same part. Here's the one I'm referring to:
From a 944

From a 931 S2


When I did a search on that part number, it comes back with the sensor with the much longer nose on it, which won't work, at least not bolt in. Like this:


I'm not worried about the length of the lead or the electrical connector...those are both easy enough to remedy with off the shelf parts. It's the sensor end that's the bugger. Even if the Bosch unit above sends the correct pulse, rigging up a new mounting system with adjustability would be a PITA in situ...

Lizard928

Erik,

Dan is talking about a different part.

Dan,
The sensor you are looking for is the TDC reference sensor. This was for a factory tool that I have never seen.
It is not required for any of the 928s and is found on all 1985+ 928s.

So essentially these sensors in the 928s are never used, and have never been used.

That said. I do believe that the standard CPS for the 928s that Erik refers to could be fairly easily adapted to do the job. However you will need to cut the factory wire off the origonal sensor and you will need to put a femail 3 pin Bosch EV1 plug onto the end of the factory wire. This will also help with not having to try to pull the sensor wire through the firewall when changing the sensor is required.

hacker-pschorr

Hmm, I don't remember coming across one of those on my 944S

ideola

I need to get a really good look at how the CPS mounts onto the S2 931. It's been a while because my boy is driving the one S2 I currently own. I'm picking up another one next weekend, which will give me opportunity to noodle over this, and maybe using the idea you mentioned on 924board about a spacer sleeve. Just need to make sure there's ample room to rig it and make sure it can be adjusted. Changing the ends and extending the cable for the 931 is no big deal. Just need a reliable way to measure how the 944 version works vs. a known good 931 version. Going to need to invest in an oscilloscope, I guess.

Lizard928

The signal will be the same from VR to VR. It is the shape of the teeth that should vary it.

If you have a dead S2 sensor mail it to me, I will look into making a spacer for you.

ideola

OK, I think I have one, I'll dig it out today. Has your address changed from when I came out a few years back?

John Speake

The same flywheel speed sensor is listed in PET from 84 through 95.
944 606 115 00 (Bosch 026 121 000 3) So what's the problem ? Is PET incorrect ?

ideola

No, that's not the same part I'm talking about...

...apparently, the "timing mark sender" to which I'm referring was only used as a diagnostic sender on the 944 and 928, and from what I've learned is non-essential to the running of those cars. It is also NLA from Porsche. I was hoping we could still get it and modify the harness end for use on the S2 931. Looks like we'll have to go with the 944 sensor instead and machine up a spacer to mount it correctly.

WallyP

Since they are not necessary on the 928, Mark Anderson at 928 International might have quite a few of them available. Perhaps you should buy all that he has...

ideola

OK, I've purchased from him before for my Euro Shark project...I'll check in with him, thanks for the tip.

John Speake

I believe that that other sensor was used with a piece of VW test equipment that required a TDC signal.

So on a 931 S2 it is required for the engine to run ?

Lizard928

Yes, it controls the DITC (ign) brain.

And Yes Dan my mailing address has changed.

John Speake

Thanks Colin !