83 sc start/ idle problems

[911-m5]

Help,
I just bought it 2 days ago and it was fine for the first two days. The guy I bought it from had the oil changed and the idle set up on it before I picked it up because it was a little rough at start up. So, I got in it last night and it didn't want to idle at all. It turned over and seemed to have spark but I could hear it sputtering and coughing when I tried to give some gas to stay running. Also, I noticed some white smoke come out of the tailpipe. It only smokes if it's been sitting for several hours-never while at speed. And the idel is all over the place sometimes it's at 500 sometimes it dances between 1000 and 2000 sporadically. However, once it is up to operating temp it idels at 1000 and seems to run fine. What's the deal? Throttle linkage sticking, flooding at start up, loose plug wires? I don't know. Any suggestions welcome.

Allan

[pbs911]

Sound like there is a problem with the warm up system. Could also be the fuel mixture. Check the motor to make sure all vacuum lines are connected and everything electrical is connected. How are you starting the car? You do not touch the gas when starting. Be sure to get a pop-off valve installed right away. It prevents against destroying the airbox in the event of a backfire.

Some smoking on start up with the flat air cooled motor is common. The oil drips down while sitting and comes up on start up. It's when you have smoke after the motot runs for a few minutes or it changes color that you have to start worrying.

[911-m5]

I did notice that it seemed a little rich the last time I got out of it.

Thanks for the info Paul.

[nostatic]

the white smoke after sitting is likely condensation (VA a bit humid these days?). It should be only at startup though.

As for the rough when cold, it could be a number of things. Mine was rough and it turned out that fuel pressures needed to be tweaked. Other classic problems are bad warm up regulator (WUR), auxiliary air regulator (AAR), and vacuum issues as Paul mentioned. When the car is up to temperature and idling well, take off the oil filler cap. The idle should drop with the loss of vacuum. If it doesn't, that is a quick and dirty indicator of a leak somewhere.

Also take a look here:

http://www.pelicanparts.com/911/technical_specs/911_cis_troubleshoot.htm

[911-m5]

Thanks Nostatic.
More than a bit humid. Pretty nasty.

I'll give the oil cap a try.