CDI problem

[aztec7]

Hello all, I need some advice. My 1973, 911 powered Fiberfab Aztec 7 needs a new CDI. Can anyone recommend an affordable replacement. Help would be apprecuiated.
Mike

[tonythetarga]

Not only is this a discussion board, but Pelican actually sells parts for Porsches!
Check the parts section for your year/model and engine size and you should find what you need.

[Early_S_Man]

Mike,

Welcome to the board! Pics of your Aztec and engine would be nice.

Most problems with CDI ignition can be traced to bad connections or points/distributor problems ... hence, here are the things to check before declaring your CDI unit dead:

1. Check that the points are opening and closing properly by connecting a 12 Volt test lamp between the trigger terminal on the side of the distributor [leaving both wires connected] and +12 Volts at the 3-position fuse block on the electrical panel that was on the left side of the engine compartment. Turn the engine over with the ignition on, and the test lamp should blink.

2. Pull the coil wire to the distributor out of the coil and connect a spare spark plug wire and new spark plug, or KD Tools 2756 or 2757 Test Spark Plug, and be sure the spark plug body is grounded! Be sure the ignition switch is on. Pull the two wires from the distributor trigger terminal, and repeatedly touch the Black wire terminal to ground as if it is a telegraph key. You should get fat blue sparks at the test spark plug!



3. If the above does not yield good sparks, remove the engine electrical panel. Remove all ground straps and clean thoroughly, both strap ends and the locations where they terminate. Remove the CDI unit from the panel. Degrease & clean the three tabs A, B, & C. Remove and clean the 'D' terminal above the special 3-pin connector with Brakleen ... wire brush the CDI body where the ground lug 'D' terminal is fastened. I suggest a bench test as shown in the Bosch Test Instructions in the 3rd or 4th link below ... the 'telegraph key' method can be used to trigger the CDI unit. If there is any corrosion on any of the terminals ... then both female Faston terinals and male tabs should be cleaned with 9% pickling vinegar and Q-tips, followed by a rinse with distilled water and blow-dry with compressed air. Slightly crimp the sides of the female Fastons with needle-nose pliers ... don't close the gap -- the intent is to just tighten the grip on the tabs slightly!

4. Even if the CDI unit is dead ... it can be repaired and brought back to life for a fraction of the cost to replace it. It is of conventional, discrete solid state analog and pulse circuitry ... transistors, SCRs, Zeners, and capacitors & resistors ... nothing exotic,magica,l or mystical about it! I have posted the Bosch parts list, and circuit variations, as well as a test document. There are several different board layouts, but the '73 model is the one that is best documented. If you have any electronics experience, or have a friend who is ... the repair shouldn't be difficult, though you probably won't find all of the repair parts at Rado Shack!

5. If your coil is leaking or has brown ooze around the cap ... a Bosch Blue coil or MSD High-Vibration epoxy-filled coil will work just fine!

Here are some resources that have given some Pelicans enough information to repair their CDI units ... you may want to peruse and print out in a binder for reference:

distributor lube...

Ignition Troubleshooting??????

Perma-tune CD or Bosch CD?

History of Bosch CDI ... toubleshooting info, parts list changes, and schematics ...

Here is what your '73 CDI should look like inside, single-sided pc board & point-to-point wiring to chassis-mounted discrete components ... almost looks like an old Heathkit project: