Please Help! 82 SC Engine cuts out on Highway!

[jrolstin]

Al, great post, thanks for the info... I only have one flag terminal and am still unsure of the polarity. on the thermotime there is a longer terminal and a shorter one. Can you tell me which length is for the positive lead, or red lead?

[GothingNC]

This will help you out with the mysteries of CIS

CIS Primer for the Porsche 911

[speedy]

you would have to trace the wiring the diagram to answer that question but I do know that its part of the harness that connects to the plug at the firewall of the engine. go to lambda system. the red relay is the fuel pump relay and yes if you pull it the pump should stop the high pitch noise from the enginge bay is the cdi box and you should hear a buzzing noise which is your freg valve

[GaryR]

Check the wiring harness that comes out of the back of your ignition, IIRC part of it goes into a plug (similar to the mirror plug) that plugs into the firewall/footwell. Be sure that isn't loose, popped out on two of us racing that I know of, kills the car dead in her tracks..

[jrolstin]

Ok I cannot find any leads going to the air flow metering sensor that would tell the fuel pump to shut off... where is the connection? I need more help understanding exactly how it is supposed to work...

[al lkosmal]

Originally Posted by jrolstin

Al, great post, thanks for the info... I only have one flag terminal and am still unsure of the polarity. on the thermotime there is a longer terminal and a shorter one. Can you tell me which length is for the positive lead, or red lead?

The terminal posts on the thermotime switch are two different sizes...two different diameters, to accept two different size flag terminals. The yellow wire goes the the terminal post with the smaller diameter, the red wire goes to the terminal post with the larger diameter. (closest to you in this pic.) Look at your thermotime closely and you'll see the difference in sizes.

regards,
al

[al lkosmal]

Originally Posted by jrolstin

Ok I cannot find any leads going to the air flow metering sensor that would tell the fuel pump to shut off... where is the connection? I need more help understanding exactly how it is supposed to work...

Here is a pic, showing the safety switch connector (blue) on the front side (closest to the front of the car...I.E. hardest for you to reach in the engine compartment) of the air flapper housing. You can reach it by reaching around from the left side of the intake..........or you can remove the top rubber cover that connects the flapper intake to the throttle body and have better access.



PS: you will need to be able to read...and understand wiring diagrams...and have, and be able to use, a multi-meter to be able to debug the wiring in your car........if you are not handy at the reading/interpreting part or the use of a multi-meter.... holler for help and see if you can get somebody local to come out and help you debug. It's a bit confusing to the uninitiated...........and wiring issues are a PITA to chase down.

[jrolstin]

Al,

I am pretty handy with reading/interpreting electrical diagrams and using a multimeter, should be able to figure it out - just needed to know where to look

Thanks a lot. I will try to take a look at this tonight when I get home from work.

[jrolstin]

As for the Thermo-Time switch... If it is not connected, will it run as if it is in cold start mode all the time? This may be the cause of my performance issue...?

[dyusem]

Originally Posted by GothingNC

Do you have a Permatune box?

I'll 2nd this question...when my '80 SC had a Permatune box installed, it experienced the same issues as the OP's SC...man, having the engine cut-off on the Golden Gate Bridge is a bummer!

If I recall, the tach would sometimes wildly bounce up/down just before the engine was cutting off or it would sometimes bounce and nothing further occurred...except my rapidly increasing heartbeat...it was stressful and after Permatune replaced the box and it failed again, the SC was fitted with original equipment and all was better.

Good luck with the diagnosis and repair!

[jrolstin]

@dyusem,

Thanks for the advice. My tach does not do anything abnormal. It reads RPM signal very clearly and does not seem to be malfunctioning. I will have a look at the CDI box tonight to see what type it is.

[jrolstin]

I am going to go to a partsource tonight and try and get some new flag terminals for the thermo-time switch.

[Ron.G]

You can set up a mirror and light behind the engine so you can see better back there. look around the area were it should be plugged in.
The connector is part of the engine wiring harness so it should be laying back there some where.

The wires being off of the thermo time switch will not make the car run rich . it only activates the cold start valve when the engine is cold. so as of now your cold start valve is not working.
When the engine is cold it makes the connection between the yellow and red wires to fire the valve. when it is warm it breaks the connection. No need for extra fuel when the engine is warmed up.

[jrolstin]

Thanks Ron for that clarification. I will have to look elsewhere for my ponies... It still feels like a lot of them have left the stable...

[jrolstin]

I got my thermo-time switch hooked up, It doesn't start up as quickly cold but it definitely runs better cold. In removing the top rubber cover of the air flapper housing I decided to check full throttle. I realized I was only getting 20 degrees of rotation out of the throttle plate. I got distracted by this, adjusted it and took it for a drive. Massive improvement... I found my loss in power!

So I also looked for a while at where the safety switch is. I felt the connection, wiggled it while on etc, no avail. Connection seems good. However I can't tell how the switch is supposed to actuate? I lifted the flapper and lowered it... I don't see anything resembling a switch... Is a contact thing? I tried bridging where I thought that might be and still nothing... What do you guys think? I need help to understand the type of switch used here... I can't determine it on my own.

Thanks!

[jrolstin]

bump

[theiceman]

holly crap what a small world .... i was just doing some research on a cdi box im trying to repair and did a search and came up with this old thread ...
I was parked next to Jonathon just on the weekend at a BBQ and we were chatting about our SCs, ( he did some nice work on his ) .

Then i read through the thread and see the pic of the back of the CIS is mine . its from when i blew the airbox and took some pic for reference coz someeone wanted to see the safety switch ...


too funny ...

[jrolstin]

Hilarious... I guess to follow up on an old thread... I didn't know what I was doing then, it's all figured out now! - CDI was replaced with MSD 6AL along with a few other tricks...

[Bob Kontak]

Originally Posted by jrolstin

Where do the wires for the microswitch come from? and what is its function? Also what is the polarity of the thermotime?

I pull the most rearward relay and the pump stops running, but there is still a high pitched noise. I plug it back in and it runs again.

That is the fuel pump relay. Swap it out with the one next to it and drive it. The rearmost relay should be red. If not, buy one. It has extra goodies inside to protect your elec system.

Also, high pitched noise coming from where?

EDIT: Oh Cripes. I need to look at dates.