rb20 r31 dies after revving (idles fine and no sputter)

[particlewav]

Hey, I have a rb20 w/r33 turbo swapped r31, the car runs, and idles fine with no issues, however whenever its revved to above 4-5k+ rpm when you let off the throttle it goes down to 0 rpm and stops running, it doesnt sputter or make and unusual noises just falls and doesnt recover. If you blip the throttle to catch it when falling its fine and goes back to idling normally. Wondering if anyone can help me out here, I really don't know what I'd be looking for on this. After fiddling with the AAC valve it seemed to fix but when I tried it again a few hours later still was doing it. Perhaps the AAC adjustments didnt do anything and instead once its warm its fine (yet to test this).

Any help appreciated.

[GTSBoy]

Probably need to properly clean the IACV. If it is dirty and sticky it can be slow to catch the idle on the way down from a rev.

[particlewav]

On 08/09/2022 at 2:40 PM, GTSBoy said:

Probably need to properly clean the IACV. If it is dirty and sticky it can be slow to catch the idle on the way down from a rev.

I'll give a good one and update, thanks.

[Duncan]

Do you know if the ECU is standard? If it is flashed or aftermarket it could also be an idle control issue in the tune

[particlewav]

Its got a nistune ecu in it

[joshuaho96]

On 9/7/2022 at 11:01 PM, particlewav said:

Its got a nistune ecu in it

Make sure the TP limit settings are sane for your load scale, I don't really expect it to have been messed with but you never know.

[EndZee]

Broooo have exact same issue. Did you solved it? Please answer 

[niZmO_Man]

On 25/09/2024 at 6:23 AM, EndZee said:

Broooo have exact same issue. Did you solved it? Please answer 

You've given zero info about your setup.

Step 1: make sure all the standard equipment are working as they should. If they're not, go investigate why.

Step 2: Make sure all your wiring is done properly. Know which RB20 you have, most likely "silvertop" a.k.a R32/A31 anything after 1989.

Step 3: make sure your ECU is tuned properly. Standard will barely run in this situation.

[EndZee]

Sorry for late answer but here’s my spec:

Series 1 1994 r33 gts25t AT converted to MT using r32 rb20det gearbox.

Custom self made clutch pedal

os giken twin plate clutch

two pins connected to let engine start

speedsensor from AT connected to wire harness but didn’t fit to gearbox So it’s somewhere inside in the car so I can add km to tachometer after I measure distance with gps. Don’t want to pay 150€ for sensor if I probably will change gearbox with adapter to bmw one. Car barely runs and winter is coming so no point right now 

engine after rebuild

Stock automatic ecu and at tachometer

Aftermarket oil cooler with separate sensor so oem oil pressure is unplugged 

koyo 53mil radiator 

Mods which may cause the issue:

600x300x76 front mount intercooler

Cone air filter blitz

Removed recirculating valve

Slighty bigger maxspeedingrods turbo

adjustable manual boost controller (didn’t set it but last time I checked on aftermarket gauge it was 0.4bar, asaik oem is different unit 7(unit) don’t want to rev it too high bcs it made max 70km after rebuild

Fuel pressure regulator set to idk 30-32psi at iddle

dw300 fuel pump

stock injectors

check valve right in front of fuel rail

i thinking sth wrong with afr it getting too much fuel and too less air or it needs that recirc valve?

on warm engine it took 5-10 seconds to start it. After I put way bigger battery, battery terminals and new ecu coolant temp sensor problem is gone

my old turbo spill 150ml oil into intake so cleaned it. 
 

I checked for error codes and it given me 55 - all good. I bought consult so will plug in soon to check if it give me better feedback. Also I will install oem recirc valve tomorrow. Small hose going to manifold but where should go 30mm pipe from this valve? I’m front of turbo inlet, after maf/ right after turbo outlet / or it doesn’t matter?

actaully can install it in these two spots (blue circles)

 

 

 

 

 

[EndZee]

here’s link to photos bcs can’t add it here

blue spots - I can install recirc valve hose there and in general everything air intake related so you can spot of anything wrong here

[EndZee]

https://imgur.com/a/wC4y8ro

[EndZee]

After I unplug maf car dies, won’t start. Same with iacv valve - two connectors mounted behind manifold

[EndZee]

Coilpacks Ngk  vag with modified igniter. It was running this way before engine blow

[joshuaho96]

57 minutes ago, EndZee said:

here’s link to photos bcs can’t add it here

blue spots - I can install recirc valve hose there and in general everything air intake related so you can spot of anything wrong here

Stock ECU with no recirc valve is a bad, bad combination. Hot wire MAFs cannot deal with reversion, even if you don't vent to atmosphere it will shoot back out when the throttle snaps closed all the way out the compressor inlet and MAF before getting sucked back into the engine. It double-counts the air, the engine runs way too lean and stumbles if it doesn't die outright.

[EndZee]

2 minutes ago, joshuaho96 said:

Stock ECU with no recirc valve is a bad, bad combination. Hot wire MAFs cannot deal with reversion, even if you don't vent to atmosphere it will shoot back out when the throttle snaps closed all the way out the compressor inlet and MAF before getting sucked back into the engine. It double-counts the air, the engine runs way too lean and stumbles if it doesn't die outright.

 

Thank you. Can you please check where should I add hose in intake pipes? From recirc valve back to intake? I upload photos on imgur. 
 

 In front of turbo inlet, after maf/ right after turbo outlet / or it doesn’t matter?

https://imgur.com/a/wC4y8ro

 

 

[MBS206]

Recirc valve goes from plumbed in just before the throttle body, and returns to between the AFM and turbo.

You'll want a vacuum source too for it from the inlet manifold.