911SC Running Perfect to Horrible to Perfect With Cycle of The Key
 

Over the last two days I have started to have a unusual problem with my 82 SC. Starts fine and drives with full power and as good as ever but all of a sudden it will start to loose power and feel like ignition breakdown. When this problem starts from a dead stop you can barley move as if the Lambda relay is unplugged. I changed the ignition wires and thought all was fine but I have discovered I still have the problem. My new discovery is that if this problem starts I can cycle the ignition key off and on and car is back to normal operation till the next time the issue starts again and with another cycle of the key back to normal.

I do not think this is a fuel problem but more of a electrical one because cycling the key makes the problem go away. Ignition switch has been replaced so I leaning towards CDI box but wanted to see the opinions of others. I have not had much luck with the search so any and all ideas are welcome.

Jon

You're partially discharging the battery during the restart. Run for a bit, battery gets over-charged again, CDI begins self-firing, rev limiter opens the fuel pump circuit.

Just a guess.

Charging system tests normal and when I turn the car off and then on I'm not using the starter. A good example is driving 60MPH in 5th and go to accelerate and car will break up ( no lean poping ) cycle key off on as fast as you can and car is fine till the next time.

like the lambda relay was unplugged....

start there. bad relay, bad connection in the plug, crusty interior light fuse connection.
unplug it when it runs bad and see if nothing changes. unplug it when it runs good and see if it's the same condition you're experiencing. some of the replacement black plastic relays lose power to the center, 87b terminal. (2 black wires/red trace). a test light in the plug with engine running will tell you.

John I took your suggestion and when the car acted up I pulled the Lambda relay. The car actually seemed to run a bit better with the relay unplugged. With a quick cycle of the key with the relay out I did notice a change for the better and the car ran like it will with the relay unplugged. I have a new relay and tried that and car runs the same, perfect then bad, quick cycle of the key back to good. I have noticed the relay is warm to the touch.

Today I switched out the Lambda box for another known good one and still having this issue.

Maybe the coil is going?

try unplugging the over-rev relay, which is mounted by the driver side front hood hinge. black relay, white plug on the bottom. what's the CO percentage at idle?