Ignition/tach Problem?
 

81 911 SC. I drove into work, a little over 40 miles, w/o any problems. Went to lunch no problem.

Leaving to come back to work the car cranked hard, didn’t want to idle and the tach wouldn’t move. Felt like it was missing. I opened up the back and it looked as if one of the plug wires had come partially off the distributor. After putting it back on a little improvement. After approximately 3 miles the tach started working.

Same symptoms coming home, except all plug wires were solidly in place. Filled her up and added some Techron to see if that would help.

I am thinking ignition issues. I have the Bentley manual but it doesn’t address the tach let alone tach/distributor interface.

Any suggestions are appreciated.

S/F, FOG

Could it be the connection from the engine wiring harness to the CDI box? For example, on my 930 there was a six plug connector that plugged into the bottom of the CDI box. On this six plug connector there was the black and purple tach wire and the green dizzy (coax) wire.

Sand,

I'll give it a shot, hopefully I'll have time tonight.

S/F, FOG

I no longer have CDI (I went to Electromotive when I had twin-plugs done), but once I did a clutch job and I didn't push that plug all the way into the CDI box...I had a few problems like you're describing. Here's to hoping it's something simple!

Sand man,

Well I tried changing out the distributor cap/rotor, re-setting the CDI connections and spark plugs. No joy.

I bought the car as a project as I’m looking at medical retirement but I’m not ready to start as I’m still active duty and I have no real pan as of yet.

Current idea now is to look at MSD 6AL or used known good CDI box for trouble shooting as an interim but…

S/F, FOG