924Board.org

[Benino]

I'm still having a starting problem on my 1980 924 N/A. Sometimes it starts sometimes it doesn’t. When it doesn't, there is no spark. (I have jumpered fuel pump to eliminate that). I've replaced the coil (no effect on problem). I checked voltages at coil with ignit on. one is 5.8V and the other is 1.8. I can't remember for sure which one is which but they are both within spec according to the book. When I try to start the car they jump around just a bit but stay around their same values. I've tried to hold the cable that goes from coil to distrib near a ground to see if it sparks when I try to start the car but nothing. I'm stumped. I wish I knew how this stuff worked. A friend of mine told me its probably my hall sender. I don't even know what that is or what it does. With the info I've provided does that sound like it could be my problem? help. I want my car to work. Any ideas would be appreciated.
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1980 Porsche 924 N/A USA
1980 Porsche 924 turbo USA
1987 Porsche 944S USA

[Smoothie]

If you had a Hall transmitter it would be inside the distributor, but they weren't used until '81, so you should have an inductive sender at the same location. I would give all the ignition wiring connections a good inspection from the distributor to trigger box on the fender, the coil, etc. It seems like you have a flakey connection somewhere.
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"..it's made in Germany. You know the Germans always make good stuff."


'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

[924RACR]

Agreed, go through and clean those connections at the ignition box, and make sure it's well grounded too - clean all corrosion off. In fact, do all your grounding points.

The ignition wiring on the distributor is real confusing, we even had 5 people looking at it once and struggled to understand. The important thing to understand other than cleaning the connections at the ignition box is that the coil receives power from one of two sources, two ballast resistors. They have different resistances, 1 Ohm and 1.5 Ohms, to reduce the battery voltage down to a level the coil wants.

Normally, when running, the 1.5Ohm resistor supplies power; it delivers a lower voltage to the coil that is sufficient for running the engine. However, since the engine is harder to start than keep running, especially when cold, power is supplied via the 1 Ohm resistor during cranking. This provides a higher voltage to the coil, resulting in a more powerful spark. Power for the 1 Ohm ballast resistor comes from the starter terminal, I think it's
indicated as a black wire, pin #16. If this connection isn't working for one reason or another, the car will be much harder to start.

Actually, again as I look at the wiring diagrams, it's further confusing... but that's how a ballast resistor system works, and I think the circuit diagrams are confusing because in this area they reverse the standard current flow and depict it as bottom to top?

At any rate, your most likely problem is a bad connection somewhere... that's always the case with intermittent problems...
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Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

[dpw928]

Thought the 80 models used measured resistance wires rather than ballast resistors. If it's not firing during cranking, the wire from the starter solenoid to the #15 post on the coil may have a bad connection at the starter or it may have been overloaded and burned through. Try measuring the voltage at the #15 post of the coil while the engine is cranking. It should have about 9+ volts.

Dennis
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81 931 5 sp
78 928 5 sp Silver
78 928 AT Euro Black

[Benino]

I think it does have resistor wires. I'm thinking the connection or maybe the wire is bad (the resistor wire from starter to term 15). which one is that at the starter end? Is that were you were saying that i't's the black one? I'm thinking of just disconnecting that and replacing it with a new resistor wire (if they have replacement ones at the porsche dealer or whatever). I hate wiring problems. btw I replaced my ground straps on the engine and on the battery maybe 6 months ago.
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1980 Porsche 924 N/A USA
1980 Porsche 924 turbo USA
1987 Porsche 944S USA

[John Brown]

Very early cars used ballast resistors; later used resistor wire. The actual diagram is identical. Yes, the 'spare' connection of the starter solenoid supplies current to the coil primary only so long as the starter is cranking the engine. Very late cars delete the dual supply to the coil as the ignition control module controls (limites) current through the coil (all the time).

Howeve, you described an intermittant no start condiction and stated that when the engine did not start there was no spark. Not that it was hard to start; but would not start and no spark when that happened. So, my first thought is bad connections in places that apply ALL the time; not just when starting.

So, determine if and where in the primary side (I would guess) of the ignition something is intermittant. A test light would be probably handiest.
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John
80 931 - #931 44Cup
99 Escalade - tows track cars
gone but not forgotten: original 924.org car - 82

[Benino]

this is true. I see no spark at all when the car doesn’t start. . .. but I have never had the car stall or sputter at all once its started and running. This is why I was thinking that it was the resistor wire from the starter. I'm not sure how ignition module knows when to power the coil. the one from the starter provides power when the starter is engaged right? the ignition module? . . .. what triggers that one?

extra info:
-in every case before when I try to start the car and it won't start. . . that's it. I can't get it to start and I have to leave it. I have wiggled the wires going into ignition module and to coil but still no start. . . The last time that I tried it and it wouldn't start, I pulled a bit on the wires going to the starter and then tried it again and it started right up. (btw. the starter always works) Could it be that the resistor wire from starter is flaky and also that my ignition module isn't doing what its supposed to do during cranking but does once the car starts??

also. . . how do Identify which is the resistor wire at the starter end? John Brown you said "the 'spare' connection of the starter solenoid" how do I know which one that is?
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1980 Porsche 924 N/A USA
1980 Porsche 924 turbo USA
1987 Porsche 944S USA

[John Brown]

I'm gonna be cranky and say just forget the current supply from he starter solenoid to the coil. That ONLY works to give a hotter spark during cranking and then completely is disconnected. It works by an 'auxillary' contact on the solenoid that is normally open and closes when the solenoid is engaged. If you get NO spark at ANY time (including cranking) spend your diagnostic energy on the main ignition wiring and function.

Which wires that go to the starter did you wiggle? Where, exactly are they located and you wiggled them?

IIRC, the 80 na feeds power to the ignition module via a black wire that comes from A12 or A17 on the back of the main fuse panel. From the module then a clear wire with a stripe goes to the coil 15. Another clear wire with a stripe also connects to the same coil 15 and this second connection comes from the starter solenoid. You could remove the wire from the solenoid to the coil and the car should still start and run and show spark. Perhaps you should do that just to simplify the troubleshooting.

The Haynes diagnostic section for ignition is really pretty good. Use it. Also, do you have a wiring diagram? If not then we are way too deep into this.

Good luck.

PS: the starter solenoid is almost impossible to work with unless you drop the starter or pull the alternator. At least for these old eyes. But, there are 2 or 3 connections. One LARGE connection is from the battery to the solenoid and is for starting motor current. One SMALL connection is from the starter switch and activates the solenoid; I believe it is either red or red/white. A second small connection is either blank or wired to the coil with, I think, clear with a purple stripe.
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John
80 931 - #931 44Cup
99 Escalade - tows track cars
gone but not forgotten: original 924.org car - 82

[Lizard]

try this, when you have no spark take a smal piece of wire and run it over to the + side of the coil and touch the other end to the + side of the battery, see if it starts, as in a few of the cars that I have seen the ICM doesnt tend to get ANY power when in the start position and it requires the booster wire from the starter to start and then when the ign returns to the run position the ICM takes over,
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3 928s,

[Benino]

I thought that was supposed to take somewhat less than 12V? does that matter? nothing will be harmed?
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1980 Porsche 924 N/A USA
1980 Porsche 924 turbo USA
1987 Porsche 944S USA

[Lizard]

[MunkPuppy]

I had this issue with my 931. The fix was pretty simple, but it took a long time to isolate the cause.

It turned out that a connection within the fusebox had either corroded or burnt out. I simply ran a jumper wire behind the fusebox to bypass the path inside the fusebox. Unfortunately, I do not remember which connections it was that I jumpered.

After I did this, the car stopped having this problem altogether, and functions just as it is supposed to. Get out your manual, and find out where the ignition switch source goes into the fusebox, and where it goes out to the Transistor Ignition Module. Bypass that and you should be rollin in no time. (provided that is your problem, of course).

Sorry I can't be more helpful. I left my manual out in the rain and it developed mold, so I'm hesitant to lay hands on it.
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'80 931 FOR SALE

"It's a shame that stupidity isn't painful"
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