I am sure the 1984 911 did not need CDI

I installed Pertronix and Nology wires and coil in my '73 911 12 years ago and it made a difference. The CDI with that same confuguration minus the coil and CD-1 coil instead made a BIG difference,

I have no experience with anything but my 1973 2.7 MFI engine with this CDI. I am not surprised that the '84 did not need it. In my mind the 1973 needs it.

wwest....do they make a trinaural switch for CDI?

"I think what we conclude here is that the older points CDI could be improved. And we have 2 choices: electronic triggered CDI or inductive and either would be an improvement."

The 911SC CDI (6 pin) has this feature, i.e. a magnetic pickup.

Seems like the 73-83 cars could use some ignition help and CDI is readily cheap available option to replace the expensive stock system. It's just to bad I have not seen any decent drop in units with electronic pickup and small ECU to just run a inductive coil. Back in the 80s I had a 75 911 2.7L and I did buy such a electronic triggered unit with simple coil. I can't recall who sold it but it worked very well and replaced the points, the cdi box and the coil. It came with simple hardware that replaced the points with a plastic trigger wheel and a simple LED with a optical pickup on the opposite side of the trigger wheel. But you don't see these simple systems any more.

The Bosch CDI in my '78 Targa has only failed me once(***), and in that instance it was the over-voltage battery charging that caused the failure. That module now has a voltage input limiting circuit, a high wattage resistor in series with the input and an "amplified" zener diode in parallel with the CDI internal circuitry.

***About three years ago and with over 100,000 miles.

The question becomes: are the old CDI systems that used the points compatible with a magnetic sensor, etc, without some sort of signal pre-processing. Were I having to address this issue I would be searching for a used or refurbished Bosch CDI module that was shipped with the magnetic sensor.

The later inductive system would be best but that requires a flywheel gear tooth timing sensor, 2 actually.

This is what I often see as response when there is no intelligent, substantive, rebuttal possible.

NO its what your get when you state: "Now that's showing a bit of unjust ARROGANCE! One person's opinion vs teams of highly educated, skilled engineers over the decades."

You had me at ARROGANCE. For me that ended the intelligent debate I thought we had going on.

"Seems like the 73-83 cars could use some ignition help and CDI is readily cheap available option to replace the expensive stock system."

The 911 ignition systems are being confused. From 1966 thru 1977 the 3 - pin CDI with points
was used. From 1978 thru 1983 the 6 - pin CDI with a magnetic pickup was used.

Dave,
So the 78-83 system would most likely resolve a lot of these issues?
Also is it possible to replace the points in 73-77 with some sort of electronic trigger? Like maybe a Pertronix aftermarket trigger that then triggers the CDI? Something like this:
Ignitor
They actually list these for the 73-77 911 cars as part #1867A.
Has anyone ever tried something like this?
Thanks for pointing out the differences.

If the shoe (glove) fits.....

This might well be a most excellent product, certainly could be...

But.....

Features...

A.) "delivers twice the voltage to the spark plugs...."

Very, even extremely, remote possibility...

They're referring, of course, to the continued use of the Kettering inductive ignition system in which the condenser is removed. In standard use that condenser primarily serves to slow the voltage rise time such that the points can reach fully open without an arc across the points themselves.

So, no doubt, the risetime would now be limited only by a snubber circuit/network in place of the condenser to protect the new solid state switching device.

Not limiting the coil primary's voltage rise time will not substantively increase the peak secondary voltage, most certainly not by a factor of two.

B.) "2:1 improvement over points in current fall time for increased coil output."

May I say....Huh?

Why, how, would the spark plug arc sustainment time/period be increased? If the now removed condenser was serving any purpose at all in the sense of spark sustainment it was providing a circuit "resonance" effect thereby extending the spark sustainment period.

Remove it, and.....

C.) "Stable timing ...no need for any adjustments."

Agreed ....in the long term sense.

Short term...the hall effect signal output waveform will change with RPM. Does the new switch trigger at the same engine rotational point as the sensor output waveform changes due to RPM...?

And lastly....

D.) "Use with Flame-Thrower 40,000 volt coil for optimal performance"

This "Ignitor" is, no doubt, a break-through product, addressing the exact problem faced by the Porsche design engineers back when the CDI was first introduced.

Then, "Optimal", OPTIMAL, performance ONLY with the Flame-thrower coil....

The way I see it the use of the base product, the IGNITOR alone, results in substantially improved Kettering design ignition system PERFORMANCE!

And just what system needs 80,000 volts, assuming we can believe the vendor statements...

Well, maybe this is the problem
 

Another chapter in the saga.

I had put in the new cap and distributor the other night and got things fired up. I did have to push to tighten the coil wire before it started... that should have been a clue.

After work yesterday I headed across town. I was driving toward a major intersection where I wanted to turn left. I had a few backfires as I approached the red light and at the light it stalled. I tried a few times and did not get it to start. Crank no start. Then the decision was to push into or across five lanes of traffic, call my wife or call AAA. Or, hop out and fix this thing.

I jumped out and went to the coil wire pushed it into the coil and into the distributor. I went back to try and got some life, not enough. I went and pushed the wire again, tried to start and got it to fire. There were backfires, but got it through a u-turn and down the road. I got it through the next intersection without incident and it seemed to be "normal" the rest of the way home.

At this point, my suspicion is the coil wire. I thought I needed to make a run to the local auto parts store to see if I could find a replacement. I was hopeful to get it right away, or else I would have ordered from our host.

I went to pull the wire out of the car, and got a bit of a surprise. The engine was hot and it took a little tugging. I got the coil end out with not much issue, then wiggled the distributor side and gave it a pull. That's when I was left with the wire in my hand and the plug was still in the distributor. I pulled the rest of the cap off, shook my head and thought that this crappy wire could have been the issue from the beginning.

I was successful in finding a part, it will arrive at the parts store early this afternoon.

I'll let the group know what the performance is after I connect the new one.

Here are photos:

http://forums.pelicanparts.com/uploa...1397230157.jpg

http://forums.pelicanparts.com/uploa...1397230227.jpg

"So the 78-83 system would most likely resolve a lot of these issues?
Also is it possible to replace the points in 73-77 with some sort of electronic trigger? Like maybe a Pertronix aftermarket trigger that then triggers the CDI? Something like this:"

That will work just fine. Many on Pelican have done just that. Some, though, don't
like it became they claim the magnets aren't perfectly aligned on the shaft resulting
in uneven timing. Others use an optical system as has been recently posted on Pelican.

Here's the link for the optical trigger;
http://forums.pelicanparts.com/porsche-911-technical-forum/805185-how-i-use-crane-optical-trig-bosch-cdi-3-pin.html

IGNITOR, good, possibly EXCELLENT, product gone bad, REALLY BAD!!!

But not nearly as over-hyped as:

Ignitor III

Wholly unsupportable claims by Marketing...

I'm not proposing using this product as intended, I'm wondering if it could be used just to trigger the 73-77 CDI box. Simply replacing the points with it but keeping the CDI stock.

I like this optical solution even better.

The one wwest mentions is the later version which does some 'trick' things.
The one you referenced works great as a points replacement or as an actual
coil driver for an inductive discharge system.

Given my history of using, mostly unsuccessfully so, optical position sensors in industrial environments, pulp mills, saw mills, etc, I would ALWAYS choose a magnetic sensor over an optical one.

Great! It looks like you had an intermittent connection due to breaks in the wire, hope that is it and you can get back to enjoying you car. I'm not really sure if anyone else is paying attention still.

No, my derogatory statements were regarding the ignitor for use as switching source for a Kettering system, not the II or the III.

I suspect the Ignitor will work fine as a trigger for a CDI system that is designed to use the points.