Need helping with s90 throttle body
 

Been having this problem with idle when my 05 evo 8 is warming up. Once the car is hot and ready to go it stops. But when I first start it, the rpms with jump to around 2kish then down to 1kish and it just bounces up and down until it goes down so low in rpms it shuts off. I start it right back up and it does the same thing. I usually just hold my foot on the gas and hold the line at around 2kish rpms until car is hot. I've read that I need to adjust the idle screw in my s90 but dont know where its located (heard its a pita to get to). Was wondering if someone would help out and shed some light

The S90 has a BISS screw, and and throttle stop screw to adjust the idle.

If the car idles steady once warm, this sounds more like a tune issue, or an issue with the ISCV.

Tune

Interesting. I just got it tuned not to long ago. By a very reputable shop. 99% of his clients are evo/dsm owners. Hard for me to believe there's something wrong with his tune.

I found a test on here i can do for my iscv and hopefully that'll fix that issue. Whats interesting is it doesn't do it all the time as well. It is a weekend car and sometimes when I first start it it runs and idles just fine

An unstable idle that goes away as the engine warms up... is generally the tune. Sorry to tell you your tuner isn't a god and may need to spend a bit of extra time on your car. The S90's are fickle to tune because the idle air bypass ports are not the same size as factory, so they generally require more work to dial in the idle and make the car behave, especially on cold starts.

like others have already said, its probably the tune. Here is a thread about the startup process and how to tune it. If you read it im sure you will recognize at what stage of startup your having problems. You can try fixing it yourself too.

https://www.evolutionm.net/forums/ec...cv-tables.html

i have the same problem when its cold out but once it warms up it idles fine my tuner who is erkel from e spec said i would need to leave the car in the cold, because by the time i drive to him its fine. I have the S90 3in, 74mm throttlebody