george44

Hello everybody, had un unpleasant experience while driving in the rain last Sunday, all went well for the first 20 minutes or so then it started to sputter and from what I could feel I believe it was only firing on 5 instead of 6 cylinders. It was going relativelly OK at highway speed but I felt it was not really turning normally, was hoping the spark was at least intermitent. When I took the exit to my house and slowed down, the fun started, idle was jumping all over the place, engine was not pulling, eventually it stalled but restarted, got a couple of backfires (thank you for the pop-off valve!), eventually got it home, home is less than 1 Km from the highway but was starting to get worried something may break. Seems all is OK, I started it a couple of days later, fires on all 6, noise is normal, pulls normal, everything seems OK, actually drove it for several hours this Sat and Sun and everything was normal. But I'm obvioulsy not comfortable with what happened and would like to get some input from the experienced folks on the list. I had this car (' 79 911 SC Euro) since 2000 and did not replace the ignition wires. Drove through rain before and alles OK, engine run flawlessly. I am obviouly ssupecting the ignition wires, I do not know what else to suspect. I have braided wires and I do not know how old they are. How can you check these wires, on normal wires you spray water and then look at night time to see sparks flying between them = bad wires but on these ones? another issue, checked Pelican, they offer three sets - Beru for $215, OEM Porsche for roughly $450 and Magnecor for $150. I'm sure there are camps for each of these but honestly now, I know Beru and I think they are very goood, I also read lots of good reviews on this forum regarding Magnecor, I do not know why the OEM set carries such a premium but as with everything in this world I suspect there is a reason. Would appreciate any advice you guys have for me especially on how to troubleshoot the system to figure out what is the problem in the wet. Many thanks,

George

TT Oversteer

You may have gotten water inside your distributor cap. Open it up and take a look next time you drive in the rain. I replaced my ignition wires with the Clewett set from Pelican. I like the quaility and the price was under $150. The only way I know of to test wires it to check each one with an ohm meter for the proper resistance. I'm not sure what the correct value is but I found one wire with a reading much different from the other five. Sure enough, the connector was corroded on that wire. Also I've heard the resistors inside the spark plug connectors get brittle over time and break causing poor performance. Sometimes you can get away with just unscrewing the connectors and replacing them as needed.

theiceman

George I would start with cap and rotor as they are way cheaper. BTW i have a set of ignition wires less than a year old ( non braided minus the main lead) . If you want you can borrow them for testing. I put my original ones back on for looks only. Both sets work flawlessly. This would tell you if your problem is in fact leads.

scarceller

My bet is also with water in the cap. I had a 75 911S that had a bad seal between the cap and distributor it always got moisture in the cap when it rained and acted as you describe.

To be certain, try spraying water around the cap with a hose, if properly sealed it should not get any moisture. Then if all looks well move onto adding water around the cables. When doing the cables do them at night in the dark as you may even see the arcing.

Nice thing is you can test all this in the driveway with a hose and not wait for next ride in the rain.

Good luck

EDIT: my final fix for my 75 911 was simply to apply silicone bead around the cap before it was installed, worked like a charm.

george44

Thank you guys, much appreciated! yes, I have a large driveway at my disposal, that should not be a problem. And Clive, thank you very much for your offer but when it's dry the damn thing runs like a charm and quite frankly I don't feel like testing or replacing the wires when it pours, I'd rather call the CAA for a tow. I'll start with inspecting and measuring the wires one by one and see what I find. Will also look inside the cap for any trace of moisture but that is now probably gone. If all checks OK I'll give you a shout Clive and see if your wires make any difference (will look for a rainy day). Thanks again,

George

ron mcatee

You may have a cracked cap.