82SC won't run after starting
 

Just did a back date of the heating system of my 82SC, removed all the original hoses and engine heater blower. Had to undo the distributor cap and removed the spark plug wires 1,2,3 on the driver side to facilitate the installation of the heater duct. Installed everything and car fired up drove it for 10 minutes and after it would turn off after stopping at traffic lights or stop sign. Engine restarts but shuts down immediately. Managed to get it home but it still starts and then shuts down.
Any ideas were to begin?Any help would be appreciated.

Double check distributor and alll wires on cap are correctly fitted. The last thing you did is typically culprit

After sitting for about an hour and starting the car, it seems to idle now but I haven't
taken out to test drive it to see if the issue comes back.
Any ideas?

Fuel pump, or fuel filter ?
Relay?
Ian

Just started it and pulled it out of the garage and let it run for 5 min, once I put it into gear and gave it throttle it turned off. The car was running well before I did the modifications. The only thing I removed was the spark plug wires the coil and the distributor cap everything else remains the same.

When engine is idling for those five minutes is it idling smoothly with no miss or back fire? What happens when you rev the engine, does it sound correct?
As Dimitri pointed out double check plug wire location, loose or incorrectly seated distributor cap. Also visually check both ends of the coil wire

Could be accidential. Must not be related to the last repair.

Check if either the spark is missing or weak - there are some ignition spark test plugs available. Be extremely careful on the super high voltages of the CDI!

Probably a dying ignition coil - for idle the power may be sufficient enough, but when trying to drive the spark is not strong enough and it's shutting down. Might also be a temerature problem of either the coil or the CDI ignition box. Do you have ice spray? Start the engine. If it stalls, cool down either the coil or the CDI box with the spray and try to restart. If it restarts - voilà.

You can check the ignition coil by measuring the resistance:
https://forums.pelicanparts.com/porsche-911-technical-forum/299530-bad-coil.html

Make sure that never ever a spark plug wire gets loose when the engine runs - this can destroy the CDI box (ignition spark backfires into the box and toasts it!).

Thomas

Could be your CDI. It's not uncommon for transistors to fail when they get hot.

Did you do anything with the vacuum lines in this work? Maybe pop one loose while doing the work and put it back on the wrong connection? Accidentally adjust ignition timing while working at the distributor?

Kind of a funny one, but maybe you bent the microswitch at the throttle--mine was bent at one time and would constantly shut off on me because it would think it was on throttle while idling.

Obvious thing, make sure those ignition wires are fully seated on the plugs.

I measured the resistance and got these numbers, my ohm reader isn't very accurate so
Primary .5
Second .690
don't know if I need to move the decimal point.

Don't get me wrong - but these numbers are worthless without any scale. If you do not know how to handle and read the values make a picture and post here.

From my very first impression - I would say there's something wrong with the coil, refer to these numbers as previously mentioned:
https://forums.pelicanparts.com/uplo...1155967959.jpg

Thomas

If he's looking at a 2k scale then that .690 would be 690ohms which is in range for that coil. I think it's 600-900 ohms. Don't know why but mine is in that same range (just had a thread about it too).

Kind of light on good information here but I'm banking on it being related to something getting dislodged during the backdate or one of the plug wires (cap wire too) not being fully seated.

So you think the coil is still good?

So set to 20K I get
.00 primary
.69 secondary

Your coil is probably okay. .5 ohm primary is good and 6.9k secondary is good.

Probably, unless you zapped it with a bad connection putting it back together. First thing before you start chasing broken parts is to make sure that you have everything back together nice and tight. If I remember my OEM plug wires right they could sometimes feel like they were on but actually took a lot more force to fully seat.

I'd say verify that you plugged everything back in properly (including vacuum lines you might have disturbed) and only then start worrying about broken components.

I've never seen a coil malfunction in this particular fashion. Usually when they fail they don't start working again when they cool down.
I'm still suspect of the CDI because that's a normal failure mode for them. They work fine when cool and then they quit when they get hot and need to cool down again.
Make sure the CDI has a good ground. They hate it when they don't have a good ground. It can fry the electronics if they lose ground while in use.

joe912/62
" The only thing I removed was the spark plug wires the coil and the distributor cap everything else remains the same."

Joe, this statement you made is where you need to concentrate your troubleshooting efforts.
If you pulled 1,2 and 3 spark plug wires off from the distributor cap then make sure you reinstalled in correct firing order.
A static ohms check on the coil is only the first check made when testing a coil, they will break down internally when engine is running. Swapping with a known good coil is the best test.

I pulled the wires from the spark plugs not the distributor.
I numbered them when I pulled them off.
But I did notice last week before doing the changes that when I started the car there was a high pitched noise, I turned it off and restarted and the sound went away. Could that have something to do with it?

The high pitched noise is from the CDI. If you hear it when the ignition is on then that's a good thing. If you don't then it's not working.
Not hearing it while the engine is running is just from the masking effect of the engine running.

Here's an easy test for you:

1. Turn the ignition to "on" with the engine cold but don't start it. Do you hear the high pitched whine? If so good.
2. Start the car and let it run until fully warm. Shut down and then try to restart. If the car is in failure mode and won't restart then again turn the ignition to "on". Do you hear the high pitched whine? If not then the CDI is in failure mode. Diagnosis bad CDI.