1986 turbo - Troubleshooting ignition failure
 

Is there a checklist for troubleshooting ignition failure on a 1986 911 turbo?
My factory manuals only describe steps for older turbos.
My coil did not meet resistance specs, so I replaced it, but still no spark.

Which CDI do you have? Permatune, Bosch?
Green wire in good condition?
Is there power to the white "T" 2 pole connector below the CDI on the red wires? (Fuse 11 or 12 up front if not)

The delayed ignition cut-off relay is a common failure. Check that 12V goes in and back out on the way to the CD unit. Or just check for 12V at the CD unit first, then if not, back track to the cut-off relay. A jumper wire with spade terminals can be used to by-pass the relay if needed. Remove relay and jumper at it's plug.

You should jump your relays to test if they are the culprit, http://forums.pelicanparts.com/uploa...1508500689.jpg
http://forums.pelicanparts.com/uploa...1508500689.jpg
http://forums.pelicanparts.com/uploa...1508500689.jpg

Timmy2 - I have the original 6 pin Bosch. I'll have to look for the white "T" when I get to the barn.
I bought a crapload of those old style fuses to replace all of them!

John Walker,
Where is that cut-off relay on Brasch's picture?

Brasch,
Nice document!
Where can I get a full copy?

920 no start
 

If I hear the CDI squealing, does thatmean it is ok, or just getting power?

If it squeals, it's getting power, but that doesn't mean it works. No spark, probably a bad CD. Might want to send it to Ingo here on the forum or to Loren at Systems Consulting, Manhattan Beach Ca to check it.

THE yellow relay should be G on this, you can bypass all of them with jumpers which is what the blue line shows to see if it works. I got these from the boards here, used them to require all my electrics and hookup all the safeties again on my 86 turbo motor. I made jumpers from wire and some tweaked bullet connector ends, I leave a couple in the car Incase a relay goes bad http://forums.pelicanparts.com/uploa...1508528067.jpg

Looks like you still have an air pump?

If my CDI is squealing and my coil is new, does it come down to the CDI and the distributor as the possible culprits?

Are you getting power to the coil? have you checked the coil wire to the distributor? checked Rotor?

And have you checked that you are getting power to your the fuel pumps

coil
 

Is the coil constantly powered, or does it get power for each cylinder?
Coil wire to dist 'looks' great. It does not have a connector outside of the dist to test at.
I will have to trace back through the harness to see if I can get AC voltage.
I had to order a new multi-meter to read small voltages - .1V, I think is what I should see.

Power to the Fuel pumps?
I did jumper the #2 fuel pump relay for one test, but still no spark

I sent my CDI to Ingo.
If it tests GOOD, I'll have to go after the green wire, which is difficult on my engine.
It disappears into the harness, with no connector to put test leads on.
I'll have to pull the distributor for further testing.
If I need a new green wire, where could I source it? I certainly don't want to buy a new engine harness.

you can check the green wire at the connector for the CD.
should be around 500 ohms between the 2 wires, 31d and 7
the 500 ohms is the coil in the dist.

another reason I like my MSD. it has an LED on it that shows it is getting the trigger form the dist. came in handy when my coil died on the road, popped my spare coil in and off I went.

T77911S
Thanks! I'll try that today.
MSD may be in my future, but I'm trying to stay stock.
I already removed the air pump crap and put a Ruf muffler on it.
Some day I'll have to explain all the changes to a new owner.

terry

just keep the original parts.
I went with MSD because I removed all the crap from under the seat and still wanted an electronic rev limiter that was adjustable.

borla exhaust? I have one too along with a zork. that borla really sounds nice.