Hi i thought i would post this in case it helps anybody else out, recently i had a problem with my 1986 3.2 carrera refusing to start at first i thought it was the well known DME relay problem so i ordered a replacement and when i fitted it there was still no signs of life, after checking all the fuses etc still no joy, looking on youtube i found a video showing how to test the operation of the two crankshaft sensors one reads that the engine is running and triggers the fuel pump to run and the other tells the ignition system where TDC is and when to fire, (both sensors are identical and are mounted next to each other on the flywheel caseing which you get to by removing the nearside rear wheel) the method for testing them is to remove the big plug from the ECU under the passenger seat and use a multi meter to test for resistance on the correct pins in the plug, ( sorry i cant remember what the pin numbers are ) when i did this i found that one of the sensors was completely dead and needed to be replaced and working on the theory that they had probably never been changed (i have owned the car for 23 years ) i thought it best to replace both, so i started looking for some and it quickly became apparent that they were not easy to get and very expensive, uk based PORSCHE specialists were asking around £200 each for genuine Bosch ones and altho there did seen to be some pattern ones shown they were all out of stock in the uk and still being shown as between £70-80 each, which still seemed like a lot of money so i decided to spend a bit of time cross-referencing part numbers firstly the porsche number to the bosch number which led to a cross with a BMW number (same sensor used on mid 80s 2.3 M serise engine) which led to a cross with many other sensor manufactures data which led me back to bosch and a sensor that they make for Alfa Romeo (unfortunatly i was unable to figure out which models it related to) a search for what i believe is an Alfa part number led me to a business seller on ebay who is based in Barcelona and had the genuine Bosch sensors in stock for 30 euros each the picture of them looked the same as the images i had seen of the porsche ones and the resistance was the same so at that price i thought it was worth giving them a try, so all in all with the postage and import VAT they arrived at my door costing £77 for the two of them, they arrived in genuine bosch boxes with the number
0 986 280 797 on it which i believe is an Alfa part number,
they were a bit of a nightmare to fit as my old ones were completely seized in their mounting bracket and the cap head bolts that hold them in snapped off when i tried to undo them but fortunately i was able to remove the bracket with the sensors in place and put it in a vice and drive them out with a drift and clean out the holes with sandpaper wrapped around a piece of dowling, fortunately i have quite a selection of taps and drills and was able to drill out the broken bolts from the bracket and drill right through them so i could rethread them and use slightly longer bolts to get a good bite on the threads, (i believe that these mounting brackets are available to buy for around £240 and if you do not have tools/skills to try and fix it yourself buying one is probably the way ahead for you, i had the tools and nothing to loose so i gave it a go and it worked out ok) putting it back together was easy enough and the car started up straight away and runs perfectly so what could have been an expensive repair turned out ok in the end, in hind sight if i was doing this again i think i would just cut the wires on the old sensors and remove the bracket with them still attached and drop them in a pot of penetrating fluid for a few days before trying to undo the cap head bolts which may prevent you from breaking them and save you from having to repair or replace the bracket, another point to note as these sensors are identical it is possible to plug them in to the wrong sockets in the engine bay don't worry too much about this if you get them the wrong way round like i did the car will start but will misfire when you try to rev it just turn it off swap the plugs around and it will be fine ( of course you could mark the plugs first to avoid getting them wrong way round but with all the drilling and tapping i had to do i was just in a rush to put things back together and forgot to do it )
i hope this helps someone and the moral is if something sounds expensive just because it says its for a porsche its always worth looking to see if its used by someone at a more sensible price.
0 986 280 797 on it which i believe is an Alfa part number,
they were a bit of a nightmare to fit as my old ones were completely seized in their mounting bracket and the cap head bolts that hold them in snapped off when i tried to undo them but fortunately i was able to remove the bracket with the sensors in place and put it in a vice and drive them out with a drift and clean out the holes with sandpaper wrapped around a piece of dowling, fortunately i have quite a selection of taps and drills and was able to drill out the broken bolts from the bracket and drill right through them so i could rethread them and use slightly longer bolts to get a good bite on the threads, (i believe that these mounting brackets are available to buy for around £240 and if you do not have tools/skills to try and fix it yourself buying one is probably the way ahead for you, i had the tools and nothing to loose so i gave it a go and it worked out ok) putting it back together was easy enough and the car started up straight away and runs perfectly so what could have been an expensive repair turned out ok in the end, in hind sight if i was doing this again i think i would just cut the wires on the old sensors and remove the bracket with them still attached and drop them in a pot of penetrating fluid for a few days before trying to undo the cap head bolts which may prevent you from breaking them and save you from having to repair or replace the bracket, another point to note as these sensors are identical it is possible to plug them in to the wrong sockets in the engine bay don't worry too much about this if you get them the wrong way round like i did the car will start but will misfire when you try to rev it just turn it off swap the plugs around and it will be fine ( of course you could mark the plugs first to avoid getting them wrong way round but with all the drilling and tapping i had to do i was just in a rush to put things back together and forgot to do it )
i hope this helps someone and the moral is if something sounds expensive just because it says its for a porsche its always worth looking to see if its used by someone at a more sensible price.
