I took my first crack at adjusting my TPS and idle screws on a JDM S5 Turbo engine but I'm not sure if I did it right. I tried to warm up the engine, but when moving the throttle I noticed it still held up a little on the cam that hits the white nub I think is thermowax driven for holding the throttle open when cold. So to get the TPS readings at throttle full closed I propped that cold-idle cam with a screwdriver.

With the throttle fully closed, the TPS resistances were a bit high so I adjusted the main throttle stop screw (fire-wall side of engine) until the full-range sensor (pin E-D) came into the 0.6-0.9kohm range specified (set to 0.85kohm). The JDM BAC valve doesn't have an adjust screw so this probably messed up my base idle speed but I wanted to see if it would idle any smoother with the TPS calibrated. With the idle resistance set, the WOT resistance also fell into the specified 3.4-5.1kohm range (about 3.5kohm).

With the full-range sensor set, I then used the two-LED method to set the narrow-range sensor with the TPS adjust screw (radiator side of engine). When it was set for 1 of the 2 LEDs on, I checked the resistances for the narrow-range sensor and they were pretty close to spec, about 0.95kohm idle and 4.9kohm WOT.

I unpropped the cold-idle cam and started her up and the idle seemed fairly stable, a little high at about 1000rpm so I thought I had at least got the TPS set correctly, but when I held the engine in neutral at higher rpms, anywhere from about 2000rpm to 4000rpm, I would get a repetitive dip of about 500rpm every second or so. Revving above 4000rpm seemed stable again. This stayed happening even after driving around a bit to make sure it was fully warmed.

I checked for codes, but there were none. Did I screw up the TPS settings?

 

uhhhh wtf. im going to have to read this tomorrow 8)