'86 930 CIS Ignition Issues Seemed To Start When Alarm Issues Started

[spoke]

Fuel pumps are running. If I short out the alarm the pumps will run as long as the key is in the ON position.

I've tried putting the Permatune in the freezer to see if heat is affecting it and when out it seems to run good then starts deteriorating. The tach will at times jump a bit, maybe a few 100 RPM or more. At times the car will stall where the tach drops like a rock and the engine dies.

Can I buy a schematic for my '86 930? I have a schematic named "Wiring Diagram Type 911 turbo Model 86 but I've found a few places where the schematic definitely does not match the car.

One thing I think I want to check is the power to the Permatune. It looks like it's powered through a relay called the "Delay Action Relay". I wonder if the power to the Permatune is steady or not.

[T77911S]

trash the permadoom!!!

if you put it in the freezer and it runs good then gets worse, defiantly trash it.

put in an MSD.

[spoke]

Originally Posted by T77911S

just get the basic 6al. about 250.

The MSD 6AL comes in several flavors as well as the coil. The 6425 is offered here on Pelican. Which flavor of 6A and coil would you suggest.

Also, I still have the broken vacuum advance can on the distributor. Any advice on how to get this corrected?

Many thanks for your help.

MSD 6AL2 6421
MSD 6AL2 64213
MSD 6AL 6425 - Offered on Pelican
MSD 6AL 64253
MSD 6AL2 6530 - programmable
MSD 6AL2 65303 - programmable

Coils offered on Pelican:
8200
8202
8207 - Different shape than the can type
8203
8222

[T77911S]

I think I have the 6425.
it has a dial for adjusting the rev limiter and it has an LED to show you are getting signal from dist. can be very helpful in times of stress.

the blaster 2 coil is what everyone suggests.

programmable will get around the broken can, but then you have to program it.
whats wrong, does it leak?

[JFairman]

Another good thing about MSD ignition parts is almost every auto parts store in the USA has some of their stuff in stock or can get it in a day or two. That can be a big help if you're on the road traveling.

If you want to mount a MSD coil in the original place on the fan housing the epoxy filled MSD high vibration coil is probably best. It's black and the same size as the Bosch coil and you can peel the MSD sticker off if you don't like it.

[spoke]

Originally Posted by T77911S

I think I have the 6425.
it has a dial for adjusting the rev limiter and it has an LED to show you are getting signal from dist. can be very helpful in times of stress.

the blaster 2 coil is what everyone suggests.

programmable will get around the broken can, but then you have to program it.
whats wrong, does it leak?

Yes, the vacuum side with the larger hose from deep inside the intake is leaking. I can't provide enough vacuum with a brake vacuum pump to make the can advance the plate.

I'm leaning towards the programmable MSD 6AL-2 assuming I can't find a working vacuum advance and a new distributor is $1800. I think I'll post a WTB to see if there's any unused vacuum cans around.

[spoke]

Originally Posted by JFairman

Another good thing about MSD ignition parts is almost every auto parts store in the USA has some of their stuff in stock or can get it in a day or two. That can be a big help if you're on the road traveling.

If you want to mount a MSD coil in the original place on the fan housing the epoxy filled MSD high vibration coil is probably best. It's black and the same size as the Bosch coil and you can peel the MSD sticker off if you don't like it.

Thanks. So what's the difference between the high vibration Blaster and the Blaster 2? I do plan on putting the coil in the original location on the fan housing.

[JFairman]

Most ignition coils are filled with oil to cool the wire windings inside. An ignition coil is sort of like a type of step up transformer.
Mount one upside down on the fan shroud like Porsche did subjects it to vibration and heat cycles. An oil filled ignition coil may eventually start to slowly leak out the oil when it's mounted like that and then the engine stops when it fails. It happened to me. It was a Bosch coil made in Brazil that leaked out oil and burned out.
Epoxy filled coils are more durable in high vibration environments when mounted upside down and will probably tolerate the heat cycles for a longer time too.

If I remember correctly Permatune replacement coils are epoxy filled too.
Mount the coil(s) over on the left longitudinal or somewhere away from engine vibration and an oil filled coil will work and last just fine.

[spoke]

I was using the standard Bosch blue coil with the Permadoom. It's about 3 years old. I swapped it with the standard Bosch blue coil on my 914/4. The 914 is running great and the 930 is still having issues.

[spoke]

I'm checking the voltage at pins 31 and 15 at the CDI connector. First start today the engine fired right up, stumbled a bit, then idled at about 1500 RPM. I have the idle screw way out from the earlier loss of idle. Voltage was rock solid at 14.05V. Ran the engine for a couple of minutes and had no tach jumping.

Came out 1/2 hour later and started it up. Ran great but the voltage was now 11.8V. After 10-30 seconds, the voltage went to 14.05V but bounced around slightly 14.05-14.00 and the tach was jumping a very little bit like less than 100 RPM. Now I'm thinking the relay driving the CDI is suspect. On my schematic it's called Delayed Action Relay.

The bouncing voltage was measured with a voltmeter. I think I want to pull the DAR and inspect, as well as put my oscilloscope on these pins to see exactly what is happening.

[spoke]

Checked in the incoming voltage to the Permadoom today. Trying to make sure the failure to start/run and running poorly is the CDI and not other things.

I put the oscilloscope on the pin 15 (VBAT) to pin 31/1 (GND). The first attempt started then died. It is shown below. The baseline is the bottom line, volts/division is 2V, and time base is 2sec/division.

The voltage rises from zero to 12V as the key is turned on the the fuel pumps run for a second. As the engine is cranked, the voltage drops initially to about 6V then rises to about 8-10V as the engine is spinning and starting up.

As the engine started and ran ok for about 1 second, the voltage rises to almost 14V. The engine started chugging at a very low RPM and the voltage drops down to 12V or so. The hash observed are negative going spikes as the CDI fires. After about 4 seconds, the engine dies and the voltage is a steady 12V until I turned the key off and the Delayed Action Relay turns off.



After a couple of unsuccessful tries to start the car, I sprayed a bit of starting fluid in the intake and the car started up and ran for several minutes.

Again after turning the key to ON for 1 second, I started the engine. The voltage drops instantaneously to about 6V then recovers to about 8-9V before the engine fires up. During the first second the engine stumbles then idles nicely at about 1500RPM. The idle screw is still screwed way out. The voltage at pin 15 is about 14V minus the negative spikes.



Here's the voltage at pin 15 expanded to 5ms/division. In this picture, there are 3 pulses in 43.5ms. This comes out to 1380RPM. The voltage when the CDI fires drops to 12V. The little quick humps in between may be from the alternator as each phase of the stator is energized.

The voltage drops to 12V may not be all that bad although it's not reassuring to see this. This may be resistance in the wiring and the relay.



After running for a few minutes, I turned off the engine and let it sit for 10 minutes while I did some other things. Came back and restarted the engine. Started right up but after a minute the tach started jumping a bit then the engine started struggling and eventually stalled.

I was able to catch some of the last few CDI firings. This trace is when the engine was just about stalling. Notice how several of the firings are missing. The engine won't run well if the CDI is not firing the spark plugs.

This testing shows the supply voltage isn't all that bad and the CDI starts having significant trouble firing the plugs.



After the engine stalled, I tried starting it right back up. Now the time base is set to 2sec/division. The engine starts up then begins to struggle and eventually dies.

After running for about 1 second, the engine starts to die, then recovers for another second but then really struggles and eventually stalls.

[spoke]

The next test I'll do is to monitor the signal from the distributor to make sure it is always firing. This way I can be sure the CDI is at fault. For this test I'll use 2 channels so I can see both the distributor signal and the supply voltage.

[Jonny H]

Spoke, stick one of our CDI+ units on it with a Bosch black coil. Plug and play. Multi spark to 10000 RPM, fires 3 times faster than MSD. Made by 911 folks specifically for the 911.

You won’t be disappointed!

[Bucketlist]

Originally Posted by Jonny H

Spoke, stick one of our CDI+ units on it with a Bosch black coil. Plug and play. Multi spark to 10000 RPM, fires 3 times faster than MSD. Made by 911 folks specifically for the 911.

You won’t be disappointed!

Being the spert in this area I thought you would help Spoke analyze his info.......not just try to sell your product.

[Jonny H]

Originally Posted by Hot Euro

Being the spert in this area I thought you would help Spoke analyze his info.......not just try to sell your product.

He's already on it, either green wire or CDI box.

As was pointed out earlier in the thread he has the wrong coil. He needs a Bosch black coil and most likely an ignition box

What is wrong with recommending my own? I designed it as an enthusiast in the first place. Yes I make some $ out of it just like Spoke makes $ out of LED conversions.

[JFairman]

Originally Posted by Jonny H

Spoke, stick one of our CDI+ units on it with a Bosch black coil. Plug and play. Multi spark to 10000 RPM, fires 3 times faster than MSD. Made by 911 folks specifically for the 911.

You won’t be disappointed!

Then advance the timing a hair to compensate.

When I've watched in car video during Nascar races I've seen MSD ignition units on the dashboard over on the right side. If it's good enough for them it's good enough for street cars and they have good phone and email support.

[spoke]

Originally Posted by Jonny H

He's already on it, either green wire or CDI box.

As was pointed out earlier in the thread he has the wrong coil. He needs a Bosch black coil and most likely an ignition box

What is wrong with recommending my own? I designed it as an enthusiast in the first place. Yes I make some $ out of it just like Spoke makes $ out of LED conversions.

I'm ok with your recommendations. Like most owners with Porsche troubles, I'm happy folks with more knowledge than I are chiming in to help out.

I checked out your products and they look very well designed. Also checked out the video wrt performance. Very thorough work.

One question about your setup: As observed in my measurements there is considerable resistance between the voltage source and the CDI. You use a lab supply in your bench testing. Do you have resistance in series between the supply and the CDI to simulate the resistance observed in the vehicle?

Many folks recommend the MSD 6AL CDI. How does the 6AL compare to your CDI?

[spoke]

Looked at the CDI input voltage as before and now I'm monitoring the signal on pin 7 from the distributor on channel 2.

In the first trace the signal on channel 2 from the distributor peaks at just less than 20V and bottoms out at -10V. Engine running steady, no jumping on the tach.

Then like a switch was thrown, the engine stumbled at bit and the idle slowed down as shown in the 2nd trace. Notice how the distributor signal dropped a lot; hardly a signal now. Within 20 seconds the engine stalled.

After this I tried removing the CDI and measure the signal from the distributor as Johnny H suggested. Now I don't see any signal at all.

[itsme]

Have you checked the resistance/ohms of the distributor internal coil when it runs and then when it doesn't? Also " I sprayed a bit of starting fluid in the intake and the car started up and ran for several minutes" makes me wonder about it being ignition related. When it dies does it always start with starting fluid?

[Jonny H]

^. Where are you measuring this ‘considerable resistance’?