Well I finally figured out (hopefully) the Idle issue I have been having since acquiring my 86' 528e. Despite replacing everything imaginable over the years the only way I could get it to idle and run decent was to richen the AFM wheel 4 clicks. Even an old stock rebuilt AFM wouldn't run well.
After a plugs, wires, cap, rotor change I was getting a surging Idle situation that over the course of 2 weeks worsened to the point it wouldn't take more than a cunt hairs throttle and finally a no start situation. Here is what I believe to be the culprit, a fried high power resistor in the Idle Control Module. You can see it up against the red end of the case below. A slowly failing resistor sure explains the issues I've been after the past years.
I have a line on one from another member and another from eBay in case one or the other is no good, but of course I'm going to try to replace the resistor on principle. Question is, has anyone tried this before and would anyone know the values so I can find a suitable replacement ?
