RPM drop when pressing the clutch after Turbo and Tune
 

Looking for some help diagnosing a small issue that has popped up on my 2010.

This summer I added a full return CJM fuel system, Injector Dynamics 1000's, FuelLab regulator, Greddy TT kit, Z1 Urethane motor mounts, as well as EcuTek Racerom tuned by Seb. Overall the car is running great but I have this small annoyance.

Video: https://photos.app.goo.gl/7s34BSSaL4jszJ9h1

When I drive normal, off boost, and then clutch brake by leaving the clutch engaged but letting off the throttle and then press the clutch pedal and hold it in the RPM drops to about 500 or so before catching and going back to 800. It should catch at about 1200 RPM and slowly settle to 800.

Now if I quickly accelerate then hit the clutch without letting the engine slow the car and get into vacuum it is much less likely to happen.

Yesterday I discovered no matter how I drive it will not exhibit this behavior if I press the clutch pedal and quickly shift into neutral. This makes the RPM settle as they should.

I've also found if I do a throttle position learn after an ECU reset the issue is actually more common. I know this also changes things like ignition timing at idle.

I'm not sure what to look at next. But I've replaced the MAF sensors, upstream O2 sensors, and I have new PCV valves on order. I've done through testing of the entire intake system and exhaust, no leaks at all.

Seb is looking at the logs but he can only do so much remotely. I'm thinking this has to be some kind of sensor input issue.

Any ideas would be appreciated!

I've come up with a better way to explain the problem I'm having.

Basically I see this idle drop (as shown in the video) if I leave the transmission in gear (MT) and press the clutch. If I press the clutch and throw the shifter into neutral it does not drop the RPM. So it's something changing when the neutral switch is active I guess.