Could my Alternator be Going?

[86 911]

I've been having a high idle issue over the past month and it all started the same time as my small under the dash electrical fire (instument lights shorted out). After I replaced the wiring, the car would simply not start. Two hours later, the car sputtered to life. For the next week I had a high idle problem where my car would constantly idle at 2K RPM. A week later the car would only idle fast in the first 30 minutes that it would be driven. After that, everything would be fine. Next, Jimmy Deering, the best Porsche mechanic around (imo) came out and gave my car a tune up. The car idled fine when cold, but after a nice hard 10 minute drive, the idle would reach 2000 rpms again. Today I drove the car for five minutes and it idled at about 1600 rpm. After shutting it off for 10 minutes and then going for a longer 20 minute drive, the car idled fine at 1000 rpms. It seems that these high idleing spurs are random . I've repaced the AAR, WUR, checked vacuum lines, rebuilt the throttle linkage, and replaced the distributor cap and rotor and koax cable. I have a feeling this "random" high idleing problem is my alternator. Is it possible or is there something else? The problem is getting better though. The car is idleing more normal as time goes by.

[ZOA NOM]

What are you doing up so late, Matt?

[86 911]

Summer vacation. Plus, it's been hot as hel! here, so night time is the best time to work on the P-car. Just finished bleeding the brakes tonight and doing some upholstery touch up. I finally got to drive it for the first time in about two weeks . It seems that the bump steer kit + turbo tie rods + sway bar bushings + rebuilt calipers make a difference! Have you finished that brake bleed on your car Rick?

[ZOA NOM]

Yep, Ag helped me run through it a couple of times at Jon's last Sunday. It still needs another go, I think.

[RoninLB]

Originally posted by 86 911
I've repaced the AAR, WUR,

is your car an '86 with a 3.0 CIS ?


if it was a CIS I'd go after the deceleration valve for a quickie info.

[86 911]

My car is actually a '76 911 with a '78 3.0 Euro SC engine. Okay here's something else I noticed:
Whenever let's say I'm in second gear and I approach a stoplight, if I leave the car in gear until the RPMs drop from the load and I let my foot off the clutch, the idle will stay ar that RPM. IE:
1) I approch a stoplight going 10 MPH in second gear
2) The tach needle is at about 1200 RPM at the moment
3) I disengage the clutch and the idle just stays at 1200 RPM

I've done this test if I bog the engine down to 900 RPM and then the idle stays there. The temporary solution: Bog the engine down to desired idle as you are approaching a stop.
What could this be? Decel valve is fine as well. Wierd...

[vash]

disconnect the decel valve for kicks. plug up both the hose and the nipple.

kill all those nasty spiders you have around there! scary!

then stick the volt meter on the battery just to see what your alt is doing.

[RoninLB]

Originally posted by vash


disconnect the decel valve for kicks. plug up both the hose and the nipple.

Bingo

We have a winner folks. It's another pelicanhead.. go figure.