Can they do that?.....

[fred cook]

A couple of days ago my SC started running poorly. After doing some investigating, I discovered that the "whine" had disappeared from the Bosch CD box. I thought that when the CD went out that the ignition would be totally dead. So, my question is, can the ignition on a SC deteriorate without completely dying?

As usual, any and all ideas, suggestions, spells or incantations will be welcome!

Thanks,

Fred Cook
'80 911SC coupe

[fred cook]

I can't believe it! Over 100 "looks" and not a single reply. Surely someone has had this experience with a Bosch CD unit before!
Come on folks, talk to me! I need to know "the rest of the story"!

Thanks,

Fred Cook
'80 911SC coupe

[rvanderpyl]

Try a more descriptive title, I looked to see what this was about, but I have no experience with what you are asking. And those people who do may not have bothered to look since you didn't say what it was you needed.

[47silver]

fred
when you say running poorly..
does it start easily?
is it a lack of power throughout the rpm range or just a certain range?
does it back fire?
does it bog down or shut off?
electronic devices (especially older ones with paper type capacitors can degrade over time and not fail all of the way) the newer integrated chips usually fail and do not degrade.
my thinking though is that the car will not run if the cd is bad so i would examine the points (mine had a wire that was rubbing on the distributor cam and caused intermediate problems, i replaced with a pertronix electronic device and the problem went away).

gary

[plain fan]

Fred, when my CD went bad in my 78 SC it went down quickly. It started out as a jumping tach and ran a little bit rough. It then seemed to start running fine only to return to the jumping tach and rough running. On the way home from work on the same day the lights(driving) flickered, the tach bounced and finally nothing at all. The engine died and I coasted to a stop. Replaced the CD unit with a permatune and replaced the wiring harness that attaches to the CD unit. The harness finally degrades over time, mine was literally burnt, melted in some places.
Hope this helps!

[Vipergrün]

When the CDI box in my SC went out, I would get a stumble at 4-5K under acceleration. I have terrific luck with the MSD unit in my current SC.

[fred cook]

Thanks to everyone that responded! The symptoms that I am experiencing (or actually the CAR is experiencing) are as follows: Starts easily but idles at about 400 rpm, reduced power throughout the rpm range, occasional bucking or mini-backfires and (this is the big clue, folks) no whine from the CDI unit. All this plus the fact that it happened suddenly seems to indicate that a component in the CD box lost it's magic smoke and went to the big electronic scrap pile in the sky. I have checked the coil for shorts or out of range resistance on both primary and secondary sides. The resistance on both sides are normal (.7 ohms on primary and 700 ohms on the secondary). There is no indication of the coil overheating or leaking. The wiring from the CDI unit appears to be in good condition. Even the infamous "green" wire that goes to the distributor is showing no cracks and is still flexible. I checked the master plug for corrosion on the connectors and found none. The power wire that feeds the CDI is reading 12 volts. The plug wires are nearly new and when the engine is running there are no crossfire arcs visible. Also, I haven't noticed any tachometer erratic behavior. No jumping around or failing to work. Anyway, that is just about everything that I can say about the situation. Maybe some Pcar owner can offer a reason/solution/explanation for this strange behavior!

Thanks,

Fred Cook
'80 911SC coupe (we will serve no whine.....)

[Vipergrün]

Fred, I have a good working spare CD box from my 80SC I'd be willing to let you borrow and swap in to see if that solves the problem. I'd just ask that you cover shipping and make sure it comes back in good condition Let me know.

-b