After two years of my car being non-running, my S4 is running again! I started it last Sunday, and I test drove it Wednesday. It started on the first pull of the key, filled my garage with blue smoke on the first start, but it has since stopped that. It now starts just fine, revs up to exactly 3000 RPM then drops to exactly 1500 RPM. The oil is at 60psi at 15000 RPM, the system voltage is exactly 13V, and it warms up just fine and triggers the thermostat right when it should.

The only remaining problem is that after warm up instead of going from 1500 to 700 or 800 RPM, the idle "hunts" between 1400 and 1600 RPM. However, it revs up just fine, and drives ok. So whatever problem is left I suspect might be minor.

Pics and vids to follow.

 

The throttle cable, including the Cruise Control, could be in need of adjustment or more likely it is a problem caused by the Fast Idle mechanism. On the rear of the throttle body you will find some linkage (closest to the passenger side). There will be an upside down screw associated with this linkage. W/the car idling try pressing downwards on the linkage that has the upside down screw. If the idle drops then you likely isolated your problem. The rod from the Thermowax should extend downward as the engine temp warms. The rod extension then presses downward on the upside down screw which then closes the primary throttle plates which lowers the idle speed.

 

Thanks for the reply satch,

I have completed the throttle body mod as suggested at:
FC3S Pro v2.0:&nbsp HOW-TO - FC3S Turbo Throttle Body Mod, and I confirmed that my fast idle mechanism is removed. So I don't think that is it, but I will recheck that my fast idle cam is fully disabled. I did take a peek and there is a slight bit of slack in the throttle cable. There is no cruise control cable.

Again, thanks. I will also check the TPS and see if that is correct. There is also the starter fluid check. In the process of working on it I did remove the UIM and replace the UIM->LIM gasket. I was VERY thorough in removing as much gasket, but maybe a little flake was left behind.