permatune to Bosch CDI

[Doug Steinel]

I am removing my Permatune box and replacing it with a Bosch CDI. Thought it would be a straightforward swap but ran into a problem when plugging in the connector to the Bosch unit.


The unit at the left is the Permatune; the Bosch is on the right.The connector now on my car that plugs into the unit here is too big to plug into the Bosch unit plus it has more prongs. Do i have to change the connector to install the Bosch unit?

[ruf-porsche]

Oh Oh

[Early_S_Man]

Doug,

That appears to be an 8-pin Turbo Permatune model ... are you using a magnetic pickup distributor? If so, you will probably have to remove the Permatune/Turbo connector and either use six insulated Faston connectors or find a scrapped Bosch 6-pin connector from a salvage yard. Individual Fastons will work fine if you tag each wire to match the diagram on the side of the Bosch CDI. There is an extra [third ground wire] ground in the Permatune/Turbo 8-pin harness that won't be needed!

Here is the link to Permatune's Turbo 8-pin model tech support page:

http://www.permatune.com/T-ignition-Porsche-930-8pin.html

Good luck!

[Doug Steinel]

Warren, thanks a ton.

Doug

[Doug Steinel]

Warren, Can you tell me what colored wires from the picture I have attached goes to which of the following Bosch CDI prongs:



31/1 ====>

TD ====>

31d ====>

A =====>

15 =====>

7 ====>




Doug

[Early_S_Man]

Doug,

Does that Permatune have a model number stamped on it? I assume that it is a model 930.

Is it possible to trace those wires [which appear to be a Permatune repair harness that happens to NOT match the factory colors] back to where they splice into factory wiring???

The color code may be for a Permatune Model MP unit-- except that the White wire may have aged to Gray, but the connector isn't for an MP unit, it is for a 930 unit! What is worse is that the signal ground wire from the distributor doesn't seem to be used!

The Permatune tech page for the wiring harness for 930 Turbo model is useless!

The current wiring scheme seems to be from a Permatune MP unit; here is the Permatune tech page:

http://www.permatune.com/T-ignition-Porsche-906-917.html

If the Permatune unit you have is a 930, then we can make some assuptions:

31/1 ====> Appears to be Brown/Black wire.

TD ====> Yellow wire assumed to be green coax center conductor at distributor.

31d ====> none present in Permatune harness -- I strongly suggest that termination point of Green Coax be found and run a new signal ground to terminal 31d.

A =====> Appears to be Black wire.

15 =====> Appears to be Violet wire.

7 ====> Appears to be Gray wire, may be aged/faded White wire.

Serious checking and verification needs to be done PRIOR to connecting the Bosch CDI unit!!!

1. Verify that Violet wire has +12 Volts present when ignition switch is on.

2. Verify that Brown/Black wire is chassis ground.

3. Verify that Black wire goes to coil terminal 'A' hot lead.

4. Verify that Green wire going to terminal #2 is coil ground.

5. Verify that Yellow trigger wire connects to Green Coax center conductor at distributor pickup coil! Verify that the distributor pickup coil has 600 Ohms resistance, +/- 10 % at room temperature from ground to Yellow wire.


I suggest that the missing ground shield connection be made with a new coax cable extension to the Green Coax distributor cable, and run it to Bosch CDI terminal 31d. A high-temperature rated coax such as Plenum-rated RG-58 [Ethernet cable] would be ideal ... run the center conductor to Bosch CDI terminal #7.

[Doug Steinel]

Warren,

The Permatune does not have a model number on it; it does have "Serial No. 19955" and is stamped "SC" and has been powering my '82 3.0L SC engine in my '77. I think I am going to have to do some detective work on this customized wiring harness. The colors of the wires going into it do not correspond to the SC colors.