Surging at idle with electrical load

[A Man Eating Duck]

Car:
1997 Golf Mk3 VR6
Automatic
127,000kms

Problem:
When the car is up to running temp, air fan on 1 or more, headlights on and the indicator is going. After about 5 seconds stopped at an intersection the cars revs raise 50 - 150 rpm and begins to surge (you can hear the engine and feel the surge through the pedals and steering wheel) to the click of the indicator, the rev gauge moves only slightly up and down (+-50rpm). If i turn off the headlights or indicator the surging stops. This only seems happens when the car is up to running temp and the car angled so the drivers side is higher than the passengers side. This problem has been happening for over a year.

What has been looked at:
Checked for codes with VAG-COM, none found.
Car has been load tested, passed.
Car has been put on a scope, no problems found.
Indicator relay replaced, no change.
Replaced all indicator bulbs, no change.
changed headlight bulbs, no change.
MAF has been replaced about 4 months ago.
throttle body has been clean 4 months ago.

I have the car booked in this Friday so if anybody has any ideas on what could be the problem i would be very grateful to hear them.

[The_Hawk]

From what I understand this problem is common in BMW's too.
Basically the alternator is too sensitive and senses a voltage drop, compensates by increasing the revs, then the indicator flashes off so it drops the revs... Repeat...

Not sure there is a solution short of permanently bumping the idle.


Sent from my iPhone using Tapatalk

[Mrk_Mickey]

Not sure there is a solution short of permanently bumping the idle.

Is it possible to get a beefier alternator perhaps?

[A Man Eating Duck]

Is there a chance it could be the voltage regulator on the alternator or would that have been picked up on the load test?