Problem with cyl. 2

[Ingemar Sward]

Hi
I have 356C engine in my Porsche 356 -65 and as long I can remember I have always problem on cyl. 2, after a long parking in the garage e.g winterperiod (Sweden) the engine will only run on three cyl.
I have to change spark plug on cyl. 2 and then all works again. If the car stand for some weeks the problem occur again. I have 1720cc with weber 40IDF.
Any ideals from 356 friends

[Martin Bruechle]

Have you done a compression test or leak down ?

[Richard Shilling]

While there is a whole list of possible causes, one quick and relatively cheap possible fix is to buy a new spark plug connector and remove, unscrew the old one, install the new one and give it a try. If that doesn't work we can give you the list. Do you have access to a 356 mechanic?

[Martin Bruechle]

Maybe swap plug wires from 1 to 2 and see if the problem goes to #1 ?

[Thomas Sottile]

Check the gap on the problem plug your piston may be hitting it a bit closing the gap some.

[George Hussey]

could be that you have a gas drip when the car sits and therefore the plug fouls. Try removing the plug and switching with the one next door and try to start

[Ingemar Sward]

Some More fact on my motor, I had this problem sence 1988 with my engine and have always change the sparkplug on cyl. 2 and then it work again.

New Pistons and cylinders are installed (shasta)
Ignitor system
New ignition cabels
New dist. Cap
New rotor
Have try Bosch spark plug same problem
NGK B7HS same problem
Maybe it Will run rich on cyl. 2 ?

[David Jones]

Ingemar, next time it happens and you pull the plug take a picture or two and post here. Is the plug fouled with a black deposit or is it wet with fuel? Lots of tests you can do to narrow down the cause.
As it is Cyl #2 it would be easy to just swap #1 and #2 ignition wires at distributor and plug end before doing anything else when it fails to ignite on #2 and see if the problem transfers to #1. If it does then it is the plug wire. If not then you can suspect the plug but do not rule out an air leak that initially causes the lack of ignition, then because the engine did run and warm up the air leak closed up so a plug change was coincident with the problem cause. One can conjecture all day but logical troubleshooting is the only real solution to a real problem.
I would also suspect the possibility of a glitch in the ignitor system as because of their construction with 4 magnets passing an inductor it is possible that in manufacture one magnet could be less efficient than the others at generating the required signal to the sensor and failing to deliver an adequate spark with a cold engine and this would be especially true on a cold 6 volt system start. Try reverting to the stock ignition and see if it starts better.
You can also rotate the rotor on the distributor shaft and see if the problem moves to another cylinder to test if the rotor is functioning correctly on all cylinders.

[Vic Skirmants]

David; you mean the igniter rotor; right?

[Martin Bruechle]

I meant 1 - 2 not 3 - 4. Lol

Some More fact on my motor, I had this problem sence 1988 with my engine and have always change the sparkplug on cyl. 2 and then it work again.

New Pistons and cylinders are installed (shasta)
Ignitor system
New ignition cabels
New dist. Cap
New rotor
Have try Bosch spark plug same problem
NGK B7HS same problem
Maybe it Will run rich on cyl. 2 ?

After all that probably the carb ? Like George said ?

After sitting, you could try swapping plugs before trying to start it, to see if the issue moves to a different cylinder.

[David Jones]

Vic, I meant the sensing rotor that sits under the ignition rotor. There are 4 magnets embedded in it and if one is weak or perhaps slightly out of position it could maybe not generate enough of a pulse with 6 volts on a cold engine. Once the engine has been run even if only for a few minutes enough heat could be generated to allow a new plug to fire. The original plug could have been wetted by the incoming charge and simply replacing it may be all that is now needed to enable ignition. I may be reaching a little but anything is possible without doing a hands on diagnosis. Little bit of straw clutching here I am afraid.

[Wes Bender]

Considering that it's long distance troubleshooting, David, I think that most of the suggestions are straw clutching. There's no substitute for hands-on troubleshooting in my book. The possible reasons for a single cylinder to have a problem are so numerous that it's almost futile to guess at individual causes. The suggestions for isolating the problem by switching units around are good troubleshooting tips. Compression or leak down test is a good suggestion too. A few minutes spent hands-on can tell an awful lot about where the problem lies.

(My $.02, but I'm sticking to it......)

[Ingemar Sward]

As i wrote the problem has occur Sence 1988 so Rhen I change to new cylinders and Pistons to fix the problem but same
Problem on cyl. 2
From the besinning I had ordinarie points from Bosch and
Change to Ignitor still problem with cyl. 2

[David Jones]

Switch carbs from side to side as they seem to be the common denominator. You can start and run the engine by manual throttle application.

[Ingemar Sward]

I also have this problem with Zenith carb. on cyl. 2 and with old and new cyl. and pistons. I change carb. to Wber 40idf still same problem with cyl 2. I have seen one new idea here I will change cabels and see if problem move to cyl 1 or solve the problem
I Will give you feedback