idle RPM drop

[concept_R]

Hi,

I do realize this is a long shot and I am just trying to see if anyone else ran into a similar issue. I don't have a datalog right now, but please see the tune file attached.

The throttle body is fully closed under idle, so all the air comes from the IAC. I have the DIY autotune idle valve body with the correct valve and I tested the valve it works as it should.
IAC valve inlet comes from a -6AN line right between turbo and IC and outlet goes right into the manifold. there are no leaks.

Here is my problem: Car starts and idles fine, but it randomly (every 5 to 10 sec) the rpm drops to where the car almost dies for a split second. it's just a 'dip' so most of the time it stays running.
Crank/CAM signal is clean, used the DIY shielded harness.
I didn't get a sync loss error.

IAC is set to closed loop and since there is no other airflow (TB closed under idle) can the valve be the issue? I realize it's hard to say without a log, just want to see if anyone had a similar issue.


Thanks!

[kjones6039]

FWIW........................... I don't know anything about MS3 so I can't be much help, but everything I have read here or in the manual (and my own experience) cautions against starting with closed loop idle. Those resources say to get the engine idling well in open loop before attempting closed loop.

Ken