Coil head scratcher

Jyet · 04-26-2023, 03:05 AM

Hello all,
I have a 83 Row 911 SC with a 76 Row 3.0 Carerra engine that I installed a Bitz Racing efi kit in. I was having an issue getting it to start up. I knew I had fuel so it was a spark issue. I tried the original Bosch coil, a new Bosch coil and a MSD coil with no luck. Just for kicks I grabbed my VW bus blue Beru coil and the 911 fired right up. I know the Beru is not the correct spec. Any ideas what the issue might be? I know the spark isn’t going to be as hot as the correct Bosch coil and don’t want to try to run it with the Beru. Thanks in advance for any help you can give.

deemsriddle · deemsriddle's Garage

Welcome to the wonderful world of coils. When an old coil goes bad, a new coil may not work either. I know because it has happened to me.You might try to find an old black Bosch coil that tests good. You should get a number of responses on this site from people that are more knowledgeable than me

GH85Carrera · GH85Carrera's Garage

Quote:

Originally Posted by deemsriddle

Welcome to the wonderful world of coils. When an old coil goes bad, a new coil may not work either. I know because it has happened to me.You might try to find an old black Bosch coil that tests good. You should get a number of responses on this site from people that are more knowledgeable than me

This. You can go buy 4 brand new coils from the Porsche dealer and 2 or 3 will be garbage non functional trash, with no guarantee the 4th works. They are all the silver coil made in Brazil.

I have a 85 and it is the 3.2 engine with no CDI box. I had to buy a used 35 year old Bosch black coil to get a good reliable coil. To find a new coil, that is the proper voltage, and will work 100% of the time is just a sad challenge.

Good luck!

917_Langheck · 917_Langheck's Garage

After finding that the beru coil worked, did you confirm that the other three in fact didn't work by trying them again, assuring that their failure wasn't the result of an inadvertent wiring condition change as a result of the installation of the beru coil?

Yikes, that's a long sentence...

Jyet · 04-26-2023, 05:14 PM

Thank you for the replies

I do have what I believe is an original Bosch black coil along with a new Bosch black coil. All test properly on a multimeter. The Beru which if my research is right has a weaker spark but fires the car up straight away. I don’t want to try to run with this coil if it will harm my engine.

917-Langheck,
I did replace the Beru with the original coil to see if it was just a fluke but still no go. I put the Beru back in and the car fired up straight away again.

deemsriddle · deemsriddle's Garage

I am restoring a 1971 911T Coupe and will be installing a 1973.5 CIS T engine. When I took the 2.4 engine out, it was running OK but it's running on its 3rd new coil. A few month's back I bought an older black coil on this forum.The seller is someone most will recognize. He had tested it and I trust him. I will install the old black coil at the time of install. There is a long thread on the issues with Bosch coils, new and used, on CIS cars but I couldn't find it. You would think Bosch would make better coils than the ones they are currently producing.