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kidporsche

G'day,
The other day while I was driving to work the back cover fell off my alternator. The car starting missing very badly and I pulled off to the side of the road. Put the cover back on and roll started the car and got home. Now my car won’t start, it turns but does not fire. I have no spark at the plugs. The plug wires, cap, rotor button and coil are all fairly new. Battery is charged and it turns over quickly. Voltage at terminal 15 of the coil is >5V. Voltage at terminal 4 of the control unit is ok. Voltage between term 1 on the coil and ground is ~2V. It does not have ballast resistors, how do I locate the resistor wires? Sensor resistance and terminals 1 and 2 of the control unit is ~8Ohms (Haynes says should be 890-1285). The Haynes suggests a new distributor to fix this problem. My question is, do distributors just die, or do they give some warning first? Is it more likely that I have a bad connection/short somewhere else in the circuit? Any other suggestions for solutions?
Thanks in advance.
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Chris
1981 924 - RoW (Australian) spec

Eturbo924 · Joined: 09 Nov 2002 Posts: 2212 Location: Londonderry NH

Well the first thing that comes to mind when you say the alternator cover fell off is that the alternator ground circuit also fell off. It is attached to the alternator with the same bolts that hold the cover on. So if the cover fell off you can be sure that the ground wire fell off. Get under there and see. If there is a braided wire just sitting out in the middle of nowhere... that is likely the issue.

Eric
eturbo924@yahoo.com
_________________
1982 924
1992 968
2003 C4S
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augidog · Joined: 03 Mar 2003 Posts: 1360 Location: New Jersey

I bet your cover shorted the alternator to ground.
I'm not sure what damage may have been done but I bet your wires went red hot and soldered themselves somewhere so you now have a fault to ground.
_________________
1978 924 95 mile daily driver.
Audi TB/POR174M/High Flow Cat/2.25" exhaust
I knew that positive thinking thing wouldn't work.

kidporsche · Posted: Tue Jun 21, 2005 11:37 am Post subject:

Thanks.

Alternator ground is in place, but I'm thinking that augidog may be right. Seeing as I have roll started the car since, is it likely that something in the starting circuit is gone? Any suggested things to check first, or am I pretty much going to have to get into the rat's nest that is the harness and see for myself?
_________________
Chris
1981 924 - RoW (Australian) spec

Ozzie · Posted: Tue Jun 21, 2005 5:15 pm Post subject:

There is a wire running from the starter to the coil via a resistor or wire resistor.
Is this has been melted, shorted etc it can cause problems.
It is for providing a higher coil voltage when cranking.
Worth a look as I had to rewire the entire loom to the starter on my girl.
_________________
Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance

Eturbo924 · Joined: 09 Nov 2002 Posts: 2212 Location: Londonderry NH

The ground would have been the first thing to check... then of course the wire loom. Much of the time that wire assembly gets melted by the exhaust heat and rusted out heat shields. I believe Performance products used to carry a nice replacement wire assembly that includes the wires to the starter and all the way back to the battery.

All with nice new shielding on it to protect it from the exhaust heat. It used to be in the older catalogs... just not sure if it is in the newer ones. Might be worth a call to them dirrectly.

Eric
_________________
1982 924
1992 968
2003 C4S
Parts Parts Parts and More parts.
E-mail me for parts you need!
Drive Fast!