Cold idle and warm idle/accel problem

[m3tal]

Hey all, just acquired a GTS-T yesterday, having some idle and accel problems. When I first startup after its been sitting for a long time and is dead cold, does the usual 1500'ish rpm, then settles down to 8-900 while still cold, and gradually will start having trouble and stall from there unless I give it a tap on the gas to keep it alive. After giving it just a tap, it goes back up to near 1000 and stays steady then slowly starts dropping back down to where it wants to stall. This tends to happen until the car is warmed up, so I've observed. Am I right in guessing that cleaning the cold idle adjustment would likely help this?

Another problem I have, that is kind of random and doesn't happen 100% of the time, but maybe half the time is that my idle sits up around 2000rpm, and when off throttle and decelerating, the car will lurch every few seconds seemingly as if I'd be giving it a slight tap on the gas. Now when the car isn't doing this, its idling normally etc. Possibly a problem with the TPS?

I took off the MAF and cleaned that today, and reset the ECU. The only code I got off the ECU was the "54 - Auto signal to ECU". I'm assuming that has something to do with an auto tranny, as the car was originally an auto, swapped to manual. If it doesn't, anyone know what it means? I suppose tomorrow I should pull the idle control , cold idle, throttle body, and just give everything a good cleaning to see if it helps. Any other suggestions?

[m3tal]

May have figured something out today, didn't get a chance to clean anything, but does anyone know the water temps where the AAC will take over from the IACV? It seems like the high idle at 2000 and the associated problem on decel happens before 170*, but once it gets near there, idles fine, so it seems...

[plankworx]

just pull both valves and clean them. should be done problems or not because eventually they will clog up.
they are also adjustable, so that may help if trouble continues after cleaning

[Skym]

Sounds like TPS is not set on idle contact (ECU doesn't switch to idle tables), engine overfuels and bogs and stalls. Startup tables are already rich at factory, so misadjusted TPS that adds more fuel doesn't help. Especially when engine is modified.

If auto engine ECU, need to adjust gear change ignition tables to be the same (on manual ECU they are the same) and using manual ECU ignition timing settings. Nistune for stock ECU with consult cable, laptop with Nistune tuning software will allow you to adjust these tables.

Auto signal to ECU means there's no communication to stock autotrans ECU, which auto ECU tells engine ECU pull ignition timing during gearchanges or when autotrans kicks down gears. Earthing that wire on ECU loom should turn this error code off (ask a autosparky how to do this). Also I think can be turned off on ECU side via tuning software, but can't find it.

[m3tal]

Didn't get a chance to take the stuff apart until today. Just to confirm, this is the IACV?

[Skym]

That's the IACV or cold idle valve.