Pulling out the sensors and looking at them isn't your next best step right now. I'd test the signals at the DME first. See below. If you have good signals, you can move on to other things. If you have a bad signal, then it's time to look closely at the wiring. If the wiring is good with no fraying under the rubber boots, then it's time to physically inspect the sensors. Yanking them out before knowing if they are the problem will just add another variable since you may change the gap in the process.

If you are not handy with electronics, you may be able to find someone to loan you a Carmonia. I made a small batch a while back and, sadly, don't think I even kept one for myself but will look. In the meantime, you should consider becoming a Rennlist Member.


I'm not a huge fan of this test, but if you are handy with a multimeter, this video shows you a way to do a simple test to see if there's any life coming from your sensors.

 

I wish I could take credit, I'm a helicopter pilot and one of our mechanics recommended this technique. I had tried everything too but you can't get any leverage on the darn things given their location, they came right out with this technique.

 

As long as you don't remove the bracket, you won't have to re-gap the sensors. I think replacement sensors are $40 a piece (they are the same) from Pelican Parts. Not a major expense but you'll have to wait a few days to receive them, might as well test while you wait as recommended. I wasn't that savvy and I figured this was more likely an issue than wiring. It was the last thing to easily replace for me and it finally got my car running. I purchased my car non running...

Speaking of becoming a member...I was trying to find the directions the other day with no luck, can you direct me to where I can do that? Thanks.

 

True enough about re-gapping if you can leave the bracket alone, but I'd still argue there usually not much to learn looking at the sensor. Once in a while, you'll find some visible damage, but testing electronically is much more informative absent fairly rare physical damage to the sensors. Nice video on the vice-grip slide hammer. I'd imagine that's a better technique when you've already committed to replacing the sensors -- seem like you could break or damage them if you get too violent with that thing?

Re membership, look at the top of the page. Right under the top blue rennlist banner, there is a black menu bar that starts with "Forums"... Membership info is in the middle of that black menu bar.

 

True, not much if anything to learn from looking at them. Thanks on the video. They actually come straight out so it's pretty hard to damage them unless the top rips off, but you can get a good grip with the vice grips. Pretty sure mine had never been replaced given the condition of my car. I had soaked them overnight with PB Blaster, I could not get them to move and they came right out with slide hammer. keep the old ones in case you do ever need to remove the bracket. Old ones can be re-used to set the gap. I don't remember the exact size, but you can glue a washer to the bottom of the old ones, then tighten down the bracket. Here is a good video on how to do that:
Membership, got it! Thanks. Hidden in plain sight. I should have joined long ago but never seem to get around to it.

 

One of the vendors for Porsche parts that is on line has a nifty plastic gauge set up that you can use to set the sensor height. They were pretty cheap if I remember correctly. 25-30 dollars for both gauges..There was a video out about how to use them..might be on U tube.

 

Be prepared if you do try and remove the sensors that this job can turn into one of the lower levels of purgatory. When I did mine, and I had my intake, cylinder head, AOS, AND brake booster removed, it was still a huge P.I.T.A. The front sensor finally gave way after fighting it for several hours only to leave half of it firmly stuck in the bracket. To remove the bracket I had to cut out the alignment piece between the bracket and the bellhousing using a Dremel and a large 2" diameter cutting disc. You can't just remove the bolts holding the bracket to the block and expect it to come out. That would just be too easy and make complete sense. Some here have said they just hammered the bracket with a chisel to destroy it in place, but don't do that because there's a 50/50 chance you'll crack the mounting ear on the block as well. After all is said and done though, installing a new bracket and getting the sensors adjusted really was a non-issue as long as you use the dowel pin for the FRONT sensor, not the back. I had to turn the crankshaft a few degrees aft to get it to show up. I had a breaker bar on the front of the engine operated with one hand, and a finger down the hole with the other. Just rotate a little bit until you feel it at your finger tip. I used an old sensor with a piece of card stock of the right approximate thickness stuck on it.

 

Thought I'd throw out an update on this, in a nutshell, the car is fixed. Found a local garage who had experience working on 944's thankfully. After testing all pins on the ECU and some time of diagnosis they did find that is was as most of you had thought, the speed / crank sensors, apparently they were a pig to get off as you also had advised on - there was cutting of the bracket involved! Apparently they had been rubbing on the flywheel (not sure why that came to be) and were cream crackered. Anyhow some new ones went straight in and a new bracket installed and bob was then your uncle. Starts on the first turn... every time. Happy days.

So thanks for all the help much appreciated! Now onto the other to do jobs...

 

I'm way over my head here, but has someone written out
a troubleshoot sequence for the prehistoric Bosche Motronic??