Rb25/30 Won't Idle Properly

[crispyvl]

could not find anything on this topic for days so here is my problem

it will rev to 2000rpm and back to 1500rpm

rb30det w/ S1 rb25de head and std internals

rebuilt std vl turbocharger

rb25det exhaust manifold

S1 rb25det ecu. tried s1 rb25de ecu and s2 rb25det ecu

nizpro hidden intercooler

has anyone had a similar problem?

here is a video

http://www.youtube.com/watch?v=I0G05z-7mIU

Edited March 11, 2012 by crispyvl

[KiwiRS4T]

I think you will need some kind of tuneability - Nistune, PFC or Link etc.

[Moodles2]

I think it might be intake related, in particular AFM reversion if the stock "accordion-style" intake has been replaced.

[DVS JEZ]

Idle motor or throttle not closing properly.

Crimp the airline going to idle motor

[GTSBoy]

Something like the IAC valve sticky would cause that too. Check fault codes too. There might be something crook.

[The Mafia]

did you use a turbo block and pistons or NA block and pistons?

You haven't given much info.

But a factory ECU isn't going to run a different capacity engine, and different turbo very well.

[bubba]

did you use a turbo block and pistons or NA block and pistons?

You haven't given much info.

But a factory ECU isn't going to run a different capacity engine, and different turbo very well.

Stock ECU or maps has idled fine on all my 30's, I would be looking for a vacuum leak or checking the afm connections.

[crispyvl]

non turbo block. i have tried changing back to non turbo injectors and trying a different 'idle valve'?

[GTSBoy]

What does the question mark in your post signify?

[crispyvl]

What does the question mark in your post signify?

was unsure on what it's called

[GTSBoy]

OK. I wouldn't have worried about non-turbo injectors, as going smaller is hardly going to help. If you've tried a different IAC valve, let's just be sure we're talking about the correct valve. There's two involved in the idling of the car. The IACV is the one at the back end of the plenum that is motor controlled by the ECU to control the idle speed at all times. The other valve is hidden under the plenum and is the cold start valve. It's electrically heated and is open when cold. As it warms up it closes off the extra air that it lets in for a cold fast idle. You don't want to play with that one, it's the IAC that's important. If you've changed the IAC with no change, are you sure that the wiring and connector for it is sound?

Also, do go look at the codes. You might find the answer right there.

[crispyvl]

i put a whole different top half inlet manifold on, no change

[bubba]

Checked all cooler pipe connections and vacuum hoses?

Does unplugging the AFM make any difference?

[crispyvl]

Checked all cooler pipe connections and vacuum hoses?

Does unplugging the AFM make any difference?

checked them all and un-plugging it makes it stall

[DVS JEZ]

I had the same issue when i cleaned my throttle bodies in my first GTR.

Also in my old r31 but that was due to dud iac valve (idle motor)

Try crimping the hose that feeds the idle motor to see if the idle drops.

Make sure the throttle cable isnt over adjusted. Make sure throttle plate is fully closed.

Make sure idle adjustment screw is wound all the way in.

Make sure cooling system is bled

[crispyvl]

I had the same issue when i cleaned my throttle bodies in my first GTR.

Also in my old r31 but that was due to dud iac valve (idle motor)

Try crimping the hose that feeds the idle motor to see if the idle drops.

Make sure the throttle cable isnt over adjusted. Make sure throttle plate is fully closed.

Make sure idle adjustment screw is wound all the way in.

Make sure cooling system is bled

will it matter with no coolant because it doesn't have any in it what so ever

[DVS JEZ]

Yes it can.

[crispyvl]

sorry but that is hard to believe

[kitto]

Sounds like a wiring issue to me.

I'm pointing straight to the AFM for the time being. I have seen similar things with dud AFMs / No AFM connected / Incorrectly wired AFM.

Because VL's wiring is SOOOO gay, and most people dont know how to correctly wire up RB's, most people miss the fact that some of the sensors have a separate power feed fed by a brown wire, and most people dont even both wiring up the crank signal, most of them run like shit.

I'd check the AFM, if you are not electrically minded, get a mate that knows RB's wiring WELL. Check for the obvious too, IE, vacuum leaks.

It is possible that the IACV doesn't even have power to it, one pin should have +12V when the ignition is on. The 0V for this valve is controlled by the ECU.

[crispyvl]

the weird thing is it ran fine as just an rb30de..