Trog

With colder weather approaching, I tried to adjust the idle on my 1984 –911 this weekend. With the prerequisite jumper in the correct terminals (B-C), and a RPM meter connected, no amount of turning (CW, or CCW) on the throttle body screw has any appreciable effect on the RPM setting. The RPM seems to always want to settle at 500RPM (way too low).

Anyone else experience this phenomenon? I hope I don’t have a vacuum leak!

Peter Zimmermann

1. The CO% must be set before adjustment of idle speed.
2. '84s are well known for intake manifold hardware that gets loose, which can cause gasket-related problems.

lfe132

Peter, is that the reason I can hear a vacuum leak on my 84 but can't find it, loose intake hardware??

Peter Zimmermann

That's something worth checking. Find an Allen wrench that fits the manifold nuts, and try to gently snug down the nuts, don't go past 16 lb/ft. If they're loose enough to turn you'll probably have to remove the manifold, replace the gaskets, and update the hardware (this is usually done when the main fuel line, part # 930 110 595 05 is replaced).

Trog

Thanks Peter. I see my holiday projects getting booked pretty quick.

lfe132

Thanks Pete.