Accelerate, slow down, clutch in, idle dips, stalls.. When the compressor is activated, the idle drops a little. I am guessing that the FICD isn't kicking in when it is meant to and not raising the idle. Engine wiring harness is new and no corrosion exists on the FICD pins. Worth cleaning or replacing? Also, what is the ideal idle speed for a TT converted to manual (auto ECU still)?
The FICD Valve, is solenoid operated therefore it is either open or closed. When power is applied there should be an audible "click". There is a spring & plunger inside the valve housing, it's possible the plunger could be stuck. What is the current idle speed?
Did the new engine harness use a "Quick connect" connector for the FICD? I found that the FICD connector is too close to the IACV connector for the "Quick Connect" type of plug to sit properly. If it is one of these, you can try taking off the metal clip and trimming/bending the plastic "ears" a bit to see if it helps the plug seat properly. I had to do this a few times and in the end pushed the plug on with a screwdriver with the engine running and AC on to the point it worked. Plug is now staying put because the bent plastic tabs are holding it to the adjacent plug. Otherwise, replace with an older style connector (see Carcraze). That's my next job.
Think mine did something similar right before the aircon compressor seized... extra pressure on the pulley/belt I guess, maybe turn it by hand and make sure yours isn't getting tight/about to seize?
Mine did that for about two years and now you mention it I don't think its done it since the aircon compressor seized and was replaced.
Turned out my IACV was faulty. The ECU didn't have any control over the idle. Replaced it and now the idle increases perfectly with the AC switched on.
