when coiming on stop and putting car in neutral, afr leans out at 16-17, rpm drops and car almost stalls. recovers to normal 14.7 and 900 rpm very slowly. does it quite often but not always.

my question is, can it be something rom related (96530706) or mostly the mechanical issue ? knackered o2, bad idle stepper motor, boost leak or something ?

havent had this issue, only began 2-3 days ago

 

Fuel pump? How old is your pump? I just went through this scenario.

 

nearly 2 years old, wallbro

don't think it's faulty. pumps strong at higher rpms and doesn't lean out

 

Who tuned it?

 

myself

 

Vacuum leak?

 

Mine leans out sometimes when coming to idle. Its as if the ecu is too slow in making adjustments.

 

oups!

 

Did you found the issue?

 

no, problem still remains

 

I have the same problem, it started last week. I increased the desired idle rpm during drive and neutral and it helped a little but there is still something weird about that.

Did you check your IAC in the throttle body?
Are you running in psi-based boost control?

 

i had this same exact problem..i cleaned out my egr valve, my throttle body and changed my throttle body shaft seals and works wayy better now...my AFR stays at 15.2 at idle!!! i know i know very stable..lol

 

also are u bov to atmosphere or rec?i think you also have a boost leak too so you might wanna do a boost leak test.

 

this happened to me. my idle is set at 1500 because it wanted to stall but that didnt help. i'm vta now with an hks.. im pretty sure it isnt leaking but ill try the vaccum test and ill try cleaning the throttle body and see how that works

 

Most of our evos 8 & 9's have the weak throttle body shaft seals from factory...thats why it leaks under boost pressure Stm has them for 35 bucks i think..i bought mine and believe me a biggg difference!