Please help quick! 930 CDI diagnostic review my results.Please!!

[lendaddy]

Well I yanked the CDI box from my '77 930 after some previous tests. I will start by saying the car was very hard to start and had a miss until really warmed up. Sometimes it just didn't want to start at all. This is all very recent and never was a problem before. Anyway I have an original 8 pin cdi in it and I checked all my grounds, result good. I checked the resistance at the green wire from th dist, .6 ohm's good I believe. I checked the DC voltage at the two coil posts when cranking and even once it was running, same result 200 volts dc, Not so good I believe right? So because of that I pulled the CDI and the pins read this. pin 1 to 2--3.3 ohms, pin 1to 3--3.3 ohms, pin 1 to 6 --3.3 ohms, all good numbers I believe. Pin 2,3,6 to case--0 ohms, good again. Pin 3 to pin 8 --16 ohms, not so good right? I will be watching this thread like a hawk for responses as I need to order anything I may neeed today UPS Red. Thanks giuys.

[E Ray]

Had what I thought were the same issues back in late December, turned out to be a simple fix, ignition wires. You might try a search on "CDI+troubleshooting" lots of good info there, thaks to early s man.

Good luck

Eric

[lendaddy]

The permatune site says the resistance between pins 3 and 8 should be 250uh. What the heck is that? Is that like .0025 ohms? or 250,000 ohms? or what? Mine measures 16 ohms which I assume is bad, No?

[lendaddy]

no one knows? damn this is killing me!

[Early_S_Man]

There are typos in the Permatune documents, as well as some mistatements of fact, and and they are not intended to be troubleshooting info for the Bosch CDI-unit! The only thing I use them for is the pinouts, as they look good when printed ... and CDI-info is scarce, and your particular unit ithe the rarest of all! But, unlike Permatune's statement that '76 and '77 models were not imported into the USA because of California's C.A.R.B. restrictions (yes, that's what Permatune says) ... they are here, but not exactly rare, and the service data is NOT in the vol. 2 - 6 manuals, but rather in the Turbo supplement, which I don't have, and won't unless it is practically given to me!

The magnetic pickup coil (pins 6 & 7 back towards distributor from the connector) is supposed to be 600 Ohms ... I hope your results were from a 0.600 reading on a 1K Ohms range, which happens to be 600 Ohms!

Your last mistatement of the Permatune value of "Pin 8 to 3 = 220uF to 250uF is normal." is confusing ... F is Farads of capacitance, H is Henrys (inductance) and O is Ohms, and all units named after persons (and the abbreviations, too) are to be capitalized!!! As I said, the Permatune values for measurements made inside their box do not apply to the Bosch unit.

Do you think you could tell us in precise terms just how you measured the '200 Volts DC?' If you used an oscilloscope, fine. Anything else wouldn't be too accurate! The pulses to the coil are supposed to be 350 - 460 Volts, but they are of very short duration.

Have you tested the coil, or looked at the condition of the green coax cable as it comes out of the distributor ... your most likely source of trouble???

Incidentally ... an SC 6-pin Bosch CDI-unit or Permatune unit will replace yours with a very minor wiring change. A 5"-10" hand-built adapter harness is all that is needed!

[lendaddy]

Thanks for your response. I checked the voltage with a multimeter(a relatively good one that has a scale for up to 1000 volts dc, whether or not it can respond fast enough to properly display the quick spikes is indeed doubtful. I got the 220uF - 250uF from the permatune site, and as I stated it's confusing to me as well. I know that Fardads is a measure involving capacitance but I have no idea how to measure it. As far as the coax from the dist I believe you are correct but I am not sure I had the meter set correctly. Did I mention it is a digital meter(if it matters). Now as for testing the coil I guess I am confused there. I forget what I get across the 2 terminals, is that the only measurement to worry about at the coil, and what should it be? Thanks and I look forward to your response.

[Targa77]

lendaddy, check permatune's site again. It tells you how to check the coil. When I took my coil off of my car and performed the shake test, I noticed that coil had a dark brown substance all along the bottom of it. This used to be oil that is inside of the coil. My coil had gone bad and caused my Permatune to go bad as a result.

[Early_S_Man]

Well, if you saw 200 Volt spikes at the coil terrminals while cranking ... there's nothing wrong with your CDI-unit ... at least while you were doing that test!

The primary side of the coil is supposed to be 0.4 Ohms to 0.6 Ohms, and most under $100 meters don't rerad resistances under 1 Ohm accurately, but don't worry about that. Between the output terminal and terminal 1 (ground side) the secondary winding should be between 650 Ohms and 790 Ohms.

You should test the CDI-unit output with an assistant cranking while you have the meter hooked securely ... wiggle the green coax right where it goes into the distributor while cranking to see if the output pulses get erratic or stop.

[lendaddy]

I will check the coil tonight and hopefully that is the problem. I will post my results tomorrow. Or maybe even tonight if I get somewhere and need help. Thanks again