RPM surge

Max abbas

hello everyone
Very few members know me here as I am only active on FB pages, and specially G pages.
I own a SC'd G37Xs, with a bulletproof trans and a few mods
I am having a problem where the car would surge after a short drive and the surge will only stop after i restart the engine.
more info on the surge and symptoms is as follows:
the surge only happens when car is driven for 5+ min, i can say operating temps.
the surge starts when the car is decelerating to a stop, before shifting from 2nd to first i can feel the car lunges slightly and i would know the surge is triggered, the rpm in gear pick up from 750 to 950 steady and remain at 950.
if i take the car out of gear to N or P the rpm will fluctuate between the 950, 2200 and the car continues to rev up and down till restarted.
once restarted it continues to drive and idle fine. until it's shut off, left to cool down for 5-10 min, start the car, drive a few minutes and the surge happens again.
the surge will never repeat iteslf once restarted and taken on a drive no matter how long until it's shut off, left to cool down for a bite or shopping etc and driven again.
this surge was a lot worst and more violent before i was able to do an idle relearn, at the time the TB's just didnt want to learn at all, so i swapped with my 350z and it resolved the higher idle which used to be 900, as well as morning start surge between 1100-2400 that used to happen until the car is at operating temps.
now when the car is a little cold the rpm's in gear pick up way too fast with the slightest tap on the pedal causing the car to accelerate fast, but will go away once it's warm.

the current mod list is as follows: Stillen kit, deleted Y intake, Full SD tune (Ecutek), 720 FIC injectors, walbro 255, berk rtps, and ARK CBE.

would appreciate any input from the OG's here as the Infiniti forums isnt as active and do not have many forced induction threads or people who have gone deep enough with the vhr engines

attempts to resolve the issue:
swapped the ABS module that was throwing a low voltage code: turned out to be the TB issue, not sure how the two are related but cool as long as it went away.
i was suspicious of the VVEL module, swapped that and it did not change a single thing.
checked all relays, Checked wiring, checked grounds. read VVEL actuator signals, Cam signal, Crank signal and it all checked fine.

ask me for any more info that i might've missed

imazman

If you deleted the Y intake did you relocate the maf sensors? And if so, i assume they are on the charge pipe? And if so, how far are they from the TB and the BPV?

/Z/

Max abbas

I am on full SD tune so no mafs

imazman

Might be a dumb question (still learning), but without mafs how is the IAT being measured for an SD tune?

/Z/

TopgunZ

If your mafs are absent and you only have a map sensor...they aren't.

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imazman

I thought a speed density tune would require pressure and temperature?

Max abbas

I am using a gtr Omni Power 4bar sensor that reads IAT's

imazman

So does that read IAT AFTER the intercooler inside the stillen plenum?!

Max abbas

Yes

imazman

Im interested, how do you hook it up to the car's ECU IAT field?

imazman

ok nevermind, i think i kind of understand. So it sounds like essentially it changes the pressure voltage it reports to the ECU based on the temp it reads...and then the tuner just tunes on pressure values? So I assume the IAT value reported be ODB2 will be n/a?