944 S Engine Surging at high RPM

[JBrooks]

I have a 1987 944S, which is my first Porsche, so I'm learning as I go. I had a rough and surging idle and found that I had a vaccuum hose off as well as the air intake was loose and nearly off at the mass air. I fixed these problems and the idle is perfect and smooth.

After the fix I noticed the car has quite a bit more immediate torque and acceleration, which I expected, but now have a bit of surging in 3rd and 4th at around 5K RPM's. The tac is not showing any noticeable change while this is taking place but I can feel it. The car still runs extremely well, so I'm left with the thought that once the vaccuum and air intake issues were corrected I have found another problem that was hidden.

Your thoughts and experience would be greatly appreciated. Thanks.

[guru944]

JBrooks;
Check hose(s) under Intake manifold and especially to Idle air control. They tend to dry out. Spray carburotor cleaner around intake and hoses with engine running (not too hot). If idle changes or you hear sifting noise then you isolated the leak... Vacuume leaks occur more on 16V(s) than 8v heads. More surface area.
Later...

[JBrooks]

Hey thanks. I will check it out this morning.