When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Sounds like the same symptoms as on my '97 M3. Was having motor stalling/cut out when acceleration while engine was cold. Problem went away after about 15 minutes (engine warmed up?). Situation got progressively worse until finally the CEL came on. Took the car to my mechanics to see what he can read from the engine error code. He readily identified the problem when I mentioned the symptoms to him, error code confirmed his diagnosis. Says that it is a common problem with the e36 and the fix was to replace the crankshaft sensor.
The simply R&R took me about two hours because it was just above/behind the starter and best to get it from under the car. Probably easy to see/get at on a car lift, but on your back...with a bit of contorting of my arm to reach around the chassis and lower control arm was finally able to get it out and in.
Pelican Part lists an OEM crankshaft sensor P/N 996-606-105-00-M14 for 993 / Turbo (1995-1998).
Finally managed to get an oscilloscope to look at the waveform generated by the crankshaft sensor.
Waveform looks ok but the voltage peak to peak seems too low.
Workshop manual mentions that it should be at least 3V and mine barely gets 2.3V
So I presume the gap between sensor and flywheel isn't correct anymore and probably is why the engine acts up while warming up.
Did someone on this forum ever corrected the gap on this sensor and is it doable without a lift or should I bring it to the shop and let them figure it out?
Great job getting the waveform. After you get the issue sorted with either an adjustment or replacement it would be good see the final waveform for comparison. I haven't adjusted or replaced one yet so can't offer any info there. Would make a good DIY if you do it yourself.
Just wanted to add a bit more after getting home so I could view this
on my computer instead of my phone.
It looks your scope is adjusted so that the vertical divisions are 0.5 V
and perhaps you have an automated measurement of Peak-to-Peak
voltage of 2.26 V or thereabouts. So your Max voltage is half that
which would be just a little over 1 V.
The copy of the 95 shop manual that I have from online
indicates a Max voltage expected (not Peak-to-Peak) and should be a
minimum of 3 V. So the situation is worse that initially thought.
Your sensor is barely putting out any voltage.
I checked the PET and Sunset Porsche Parts Hub and the sensor is the
same for the 95 and the 97. They have a PN of 911-606-217-03.
Now on my car, which is a 97, I get a Max voltage of about 20 V.
I don't see how you could adjust yours to make up the difference.
You'll probably need to replace it.
Can this sensor wear out? I tought it was more like it works or it doesn't.
The workshop manual also states that if the sensor output is less than 3V the gap should be corrected.
I will probably first try to measure and/or correct the gap before ordering a new sensor. Cheaper that way
Also check connections for signal and ground. Could have resistance somewhere. Not familiar with all the failure modes. One I read about is a failure when hot.
I did adjust the sensor gap when i put in the lightweight flywheel (different gap vs dual mass flywheel), but that was with the engine / tranmission out of the car.
If memory serves, there is an odd shaped rubber plug on the upper side of the bell housing which can be popped out to open an inspection window. The sensor gap can be checked and adjusted through the inspection window. The plug is located at position 26 in diagram below.
However, I think it would be very difficult if not impossible to do this with the engine/trans inside the car. I would be inclined to take the car to the shop and ask them to price it out, maybe they have some magic tools / special borescope for this.
Last edited by bcameron59; 08-02-2015 at 12:08 PM.
Reason: Add picture
You can get to the sensor on a 3.2 car. Having said that, the 993 May be tougher with subframe, etc. But it should be accessible. Two socket head screws. One a pivot, and the other in a small slot. LH side of motor at the top of flywheel.
Ed, you might be right with the 993 too, but pretty sure it would be a tight fit, and the install would be by feel, without visual. If I recall it was a bit tricky even with the engine out, I remember thinking it would be almost impossible with engine in. But maybe you could loosen the bolts, get the gapping tool in there and re-tighten in the space available.
OP, if you get in there, it's possible you may find the sensor has somehow got loose and lost the correct gapping position, in which case you could reset it and hopefully solve the issue. If the gap is correct and you go ahead with replacing the sensor, note there are some other replacement parts recommended at the same time - see item, 9 and the 3 items following.
Thanks for all the help.
I'm leaving on holiday very soon so the repair will have to wait untill september.
I'll probably let my mechanic do the job because I don't have a lift and access to the sensor is indeed very limited.
I will keep you updated but it will take a few weeks.
You can get to the sensor on a 3.2 car. Having said that, the 993 May be tougher with subframe, etc. But it should be accessible. Two socket head screws. One a pivot, and the other in a small slot. LH side of motor at the top of flywheel.
+1
yep, it isn't too bad to change the sensor on a 993
remove the heater tube to help clear the way...
and to the OP, see post 38 from about a year ago
You have been working on this for a very long time
07-06-2015, 10:46 PM
