Crank sensor change
 

Hello all,

My 944 stopped running ...again. It seemed to miss a bit when the engine was cold, but as it warmed up, it would run great. Long story short, I went out one morning tried to start it, but it cranked and cranked and no start. In the evening, after a warm day, voila it started. The next morning, nothing. Anyhow, I am not getting a spark or injector pulse. I do have fuel pressure. I suspect that its the reference mark sensor or the other one.

What is the procedure for changing these sensors and are they the same part?

Thanks in advance for any help,

PIA to get to. but it's pretty much unbolt and remove.

if you move the mounting bracket you will need to get the spacing correct.

use www.clarks-garage.com for process.

Over time the sensors lose their ability to 'sense' the magnetic field of the TDC pole and the teeth of the ring gear.

They are the same part. The BMW equivalent is significantly cheaper. (not sure of part number)

Did you try setting them first? Clarks-Garage has a good writeup on setting them:
http://www.clarks-garage.com/shop-manual/ign-02.htm

Very helpful and it may resolve your issue if money is short. Who knows...

Now... while you're cranking the car over and it will not start, are you seeing the tachometer move?

I'm looking to replace mine (87 na) and found a vendor http://www.*************** that sells both BMW and Porsche replacements. I used an 85 BMW 735 as a reference on the search and it returned a part # of 026121002. The Porsche part # is 026121003 and both look to be the same. Anyway, I can almost buy 3 of the BMW's for the price of one Porsche. At $51 versus $141 I think I will take the gamble. There is also an eBay vendor selling these for $75, and the part number used in the listing is 026121002 and advertised as a 'direct replacement' for the 026121003 #. Either way, I will find out if it works or the real definition of assume.

Rob

I bought (2) sensors on e-bay with the 002 part number. I gave the guy a call and he said the only difference between the 002 and the 003 is the cable length. The 002 is longer. He said he will verify this again with Bosch and will get back to me tomorrow. I will post his response.

Just replace the sensors - don't mess with the mounting plate unless you have good reason to suspect it's moved; i.e. you just replaced the clutch and had the bell housing off.
While you're waiting for the new sensors, spray the old ones down with PB Blaster. The BMW sensors should be fine with the longer wires.

Before you put the new sensor in make sure you wipe it with a dose of anti-seize. Makes getting it back out again much easier. Don't get any near the tip... just the shaft please, just the shaft. :)

Well, I replaced the sensors and no go. There isn't any tach bounce. Looks like DME replacement time. Does anyone have one for a NA 83 that they want to part with? Is there an alternate model of DME that I could get like a BMW?

I have a spare at the shop that I use for testing, I would prefer not to sell it but I could send it to you so you can swap to determine if it IS the DME. That way you don't have to drop any more $$ if it isn't the problem. Just like loaning out my tensioning tool, all I ask is that you cover shipping.

Let me know!
-Nick

Did you try swapping connectors? It is possible to plug them in opposites.

I put in a different DME and it fired right up. Thanks for all of the help guys!

kind of a wierd queston.. if the tach did bounce what would be the problem...?

No spark or no fuel.