let me start with what i have done to try and fix the problem.

i have done boost leak testing. i dont here any leaks.

i let the car warm up and i tried the ''speed adj. screw mode'' to setup the BISS and got nothing.

MODS
2.0L
built head/cams
DI manifold hypertune TB. with idle stepper motor ''iscv''

i recently went from MAF0015 to SD0015. on my way home from the tune the car idled fine. granted the car ran like crap the idle was fine.

the car has not moved since. when it got tuned it was on a jdm 3 bar. i then made all the changes to omni 4bar. at this time the idle went nuts. i was getting help from a member here but i think it was a bit hard not being inside the car to try and help out. so now i am making this in hopes to get it solved

the idle is ok on initial cold start up. right around 1200rpm. once the car starts to warm up the idle increases all the way up to 2500/2700rpm and sits there. when i rev it to see if it will drop it go's right back to 2500rpm and then starts to jump rapidly from 1500 to 3000rpm up and down over and over.

someone please help. i have not driven or enjoyed this damn car in over a year

 

I have been helping for a couple of weeks now with this issue. We have tried everything I can think of, can anyone with a DI IM and a Hypertune TB runing the stock ECU confirm they have no idle issues.

Anyone know how to test a idle stepper motor for correct operability?

 

what afr's and timing do you see during this period?

 

the wideband did not log. oops. i will have to check that.

timing is between 7 and 9.

 

log afr, timing, fuel trims, ipw, rpm and boost during idle. this should give a bigger picture.

 

i have all that. how do i post up a log??

 

did this work?

edit guess not. i dont know how to upload a log

 

Im having a lot of issues with cold start idle when I switched to SD as well. We were able to resolve the 2k stutter issue on my '03 evo8 so its just getting this cold start issue licked. Is there possibly a problem with the setting in the roms being used? My car has standard bolt-ons. Ran perfectly fine MAF but now has all kinds of issues with SD patch.

 

I'm betting if you log the idle stepper position, it is moving around a great deal in sync with the RPM changes.

My car will fast idle up to 2000 RPM then slowly fall down over a minute or so after a cold start.

I can get it to not do this with the MAP VE table, but then the car runs like *** when it's warm. I believe it is related to the fact that load is calculated off the MAP VE table and with load being used every where in the ECU, the different loads associated with the SD variables force the car into operating at portions of the map not intended for idle conditions.

 

look for leaks around the TB they are not easy to find,

is the TB gasket ok ???
might have a vac leak on the manifold

but it sounds like the ISCV is stuck open when the engine is cold the coolant temp closes off a part of the ISCV system and when the coolant temp raises it opens the ISCV system fully this is causing the engine to rev high when hot as the ISCV cannot lower the bypass air

 

some updates.

i changed the omni 4 bar out for the jdm 3 bar. oddly the car ran much much better. it was doing its best to hold a 1k idle. as the car warmed up it was idling around 1300/1400rpm. this never happen before as it used to idle 2500 to 2700rpm. as it was idling the afr's where in the 11.1 10.9 range. now the car was fully warmed up. running for a good 10 minutes. before today it would run for about 5 minutes and then jump to a higher rpm. i figured i had found the issue AND THEN i shut the car off to grab my laptop to log it. when i started the car it immediately idled at 2500/2700rpm. back to step one again.

so it was good until i shut the car off. when i restared it it went back to its bad habbit.

now what?? im going to pull the idle control valve thingy off now and inspect it. im about to let the car sit under a tree and let it rot.

 

It's all in the MAP VE and RPM VE table.

Two possible situations really.

1. Idle air control valve is opening and closing due to loads and other conditions you are hitting.

2. Valve is open enough to cause a high idle speed. Engine revs up to above the fuel cut threshold, ECU sees throttle is closed and above fuel cut threshold so it cuts fuel. Engine speed falls back below threshold, fuel turns back on...lather, rinse, repeat.

Log the ISCV channel and see if it is varying with the engine speed.
Log IPW and see if the ECU is cutting fuel.

 

odd. im going to take a picture of this thing and post it. it looks like a chipmunk was chewing on it or something.

or maybe its right i dont know

 

how does that look?? normal?? it was a bit dirty too

 

I was helping him and watched this car do some weird stuff over a remote computer session. That sensor looks OK I guess, anyone else know if that is normal or not?