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Hey all, if you've been following my thread since 2023 (https://e9coupe.com/forum/threads/h...-legends-of-the-east.41708/page-4#post-386592) which described the strange problem I experienced after getting my car back from the movie shoot (The Big Cigar), I finally found a new problem and solution (thanks to Don's diagnosis) which might help some of you someday running EFI with a crankshaft position sensor.
In late 2022, when I tried to triage the problem with my ignition cutting out intermittently and coming back on mysteriously sometimes, one of the early swaps I did was a new coil and crankshaft position sensor. My local repair shop installed a Hella crankshaft position sensor for $40 which didn't solve anything. But I did notice from that week going forward that sometimes, after I'd wash my car, my E9 would not start up for 30 minutes or so (crank only but not ignition). I chalked that up to water getting close to the coil connections or distributor and needing to dry off. I even concluded once that water was getting in the intake system in another post but that was a red herring.
This last weekend at the Vintage, when my car wouldn't start after a long day in the humid heat (and driving through rain that morning to get to the event), @Ohmess came by and another BMW mechanic to inspect my car. They removed the coil wire to the distributor to see if I was getting spark and I was only getting one spark event on cranking. Talking with Don on the phone after that and he asked me to verify the CPS color which was full black plastic (unlike the shiny metal BMW OEM CPS shown here); he said his shop had lots of problems with aftermarket CPS not making a reliable and consistent magnetic readout of the missing tooth on the flywheel. When I grabbed the sensor I could feel it rocking slightly laterally even though the anchor bolt was fully seated. So maybe there wasn't the proper distance between the CPS and missing tooth and water/humidity made things worse? My car eventually started and I drove back to the hotel worried it may not start again.
The next morning, after bunking at Tom Baruch's house with Chris close-by, we started on the alternator repair to get my car on the road so I could head home the next day. But no go, the start up problem was back and it was a humid morning. And the CPS was still jiggling a little even though the bolt securing it was tight enough. @Ohmess thought of a new approach to put a washer on the bolt to allow the bolt to not bottom out and maybe place the sensor to its spec distance -- and that worked! Perhaps now the Hella CPS was at the proper distance it needed versus being right on the margin and things like moisture would through it off.
But I'm still going to swap in the new OEM CPS as soon as I get home even if the washer treatment seems to be working well enough for now...fyi, my fuel injection is L-Jet on 1984 M30B34 Euro high compression block with Megasquirt EFI. The correct CPS for me is 12141720857 and it cost $160.
A long time of start up mysteries hopefully resolved with the humble crankshaft position sensor! Thanks a ton to Don and Chris!
In late 2022, when I tried to triage the problem with my ignition cutting out intermittently and coming back on mysteriously sometimes, one of the early swaps I did was a new coil and crankshaft position sensor. My local repair shop installed a Hella crankshaft position sensor for $40 which didn't solve anything. But I did notice from that week going forward that sometimes, after I'd wash my car, my E9 would not start up for 30 minutes or so (crank only but not ignition). I chalked that up to water getting close to the coil connections or distributor and needing to dry off. I even concluded once that water was getting in the intake system in another post but that was a red herring.
This last weekend at the Vintage, when my car wouldn't start after a long day in the humid heat (and driving through rain that morning to get to the event), @Ohmess came by and another BMW mechanic to inspect my car. They removed the coil wire to the distributor to see if I was getting spark and I was only getting one spark event on cranking. Talking with Don on the phone after that and he asked me to verify the CPS color which was full black plastic (unlike the shiny metal BMW OEM CPS shown here); he said his shop had lots of problems with aftermarket CPS not making a reliable and consistent magnetic readout of the missing tooth on the flywheel. When I grabbed the sensor I could feel it rocking slightly laterally even though the anchor bolt was fully seated. So maybe there wasn't the proper distance between the CPS and missing tooth and water/humidity made things worse? My car eventually started and I drove back to the hotel worried it may not start again.
The next morning, after bunking at Tom Baruch's house with Chris close-by, we started on the alternator repair to get my car on the road so I could head home the next day. But no go, the start up problem was back and it was a humid morning. And the CPS was still jiggling a little even though the bolt securing it was tight enough. @Ohmess thought of a new approach to put a washer on the bolt to allow the bolt to not bottom out and maybe place the sensor to its spec distance -- and that worked! Perhaps now the Hella CPS was at the proper distance it needed versus being right on the margin and things like moisture would through it off.
But I'm still going to swap in the new OEM CPS as soon as I get home even if the washer treatment seems to be working well enough for now...fyi, my fuel injection is L-Jet on 1984 M30B34 Euro high compression block with Megasquirt EFI. The correct CPS for me is 12141720857 and it cost $160.
A long time of start up mysteries hopefully resolved with the humble crankshaft position sensor! Thanks a ton to Don and Chris!
