My S4 na has this annoying think that it cannot hold a steady idle when just off of idle, i guess under 10% throttle, the throttle movement before the aux throttle plates open. It feels like the ecu thinks the throttle is fully closed and cuts the fuel injectors for 1-2 seconds, then turns them back on. Makes it real lurchy when driving slowly down the back alley. My TPS was perfect at 1V at idle hpt seen at the ECU connector, i since turned the tps adjustment to increase the idle voltage and the throttle position this occurs is closer to fully closed idle position, i csn probably increase the tps setting mire, but it will be no where near what it should be. My idle is a steady 800rpm, with the tps adjusted correctly the idle used to hang at 1100rpm and the engine would shake, and other times would be a smooth 800rpm. Would a goofy map/pressure sensor cause this?

 

Did you set the TPS with the engine HOT? like, half hour drive hot? Mine did the same thing and it was all TPS

 

TPS was set hot, like driving home from work for 30 minutes in rush hour traffic at 30ēC hot. And I also pushed down the cold start cam so it was completely off the throttle, but since it was hot, made no difference. I gave my TPS screw another half turn for a total of 2 turns out from correct TPS setting, and my range of throttle where this issue happens is getting smaller.

Coming home from work today, driving down our back alley in 1st gear at about as little throttle as possible I was almost getting whiplash lol, and I was at about 3000RPM. The frequency is erratic, and no where near consistent.

 

Might be the tps that's shot. I have the same problem too.