Rb25 Wont Catch Falling Rpm

[Jarrrrrrrrrrod]

hey guys

i am almost track ready with my rb25 s13 build but i have a few issues that need sorting first.

the main problem is the engine isnt able to catch the falling rpm when coming off the throttle. the engine will idle all day but when i blip the throttle the rpm will increase then fall past the idle and the engine will stall.

what voltages should i be seeing coming from the brown and purple plugs for the AAC valve?

i have done all the wiring needed for the conversions and believe it could be electrical, if anyone else has an idea of where to look please tell.

[StevenCJR31]

Sounds like a vacuum leak

[Jarrrrrrrrrrod]

my boost/vacuum guage shows around 24 in hg vac at idle and increases when I let off the throttle.

my bov is venting to amostphere and I read this causes problems however the bov came off my old rb25 r31 which didn't have the idle problem.

[StevenCJR31]

Was the ecu in the 31 aftermarket?

[Got a Pulsar]

Plumback the BOV and see what happens.

Even if it fixes nothing, at least it will be as it was designed.

[DR3AMN]

When i bought an aftermarket BOV that vented to atmosphere i got told to keep the standard one that vents back because if it doesnt then it will stall after getting off the throttle. So change the BOV to a recirculating one and see how you go.

[Jarrrrrrrrrrod]

shit ay, thanks for the input

the 31 was running a standard rb25 ecu which is why I kinda ruled out the bov being the problem. unfortunately ill have to weld a tag onto my intake pipe and tap a fitting in so I can recirculate the air.

[R.3.2.G.T.R]

can you block off the bov all together to see if this changes the behaviour? a plate of some sort, before you start welding

[Plattsy]

BOV.

sorry mate. blocking it should do the trick.... cut up a coke can.

unless its auto. then plum back is the only way!

[Jarrrrrrrrrrod]

before all of this iv

just got another question. what gives the signal to increase the rpm at idle when electircs start to get turned on like headlights/high beams and my electric cooling fans? at idle I can switch both fans on and the head lights and the idle will drop. I believe iv

missed something when wiring up all sensors.

[Jarrrrrrrrrrod]

and am I posting in the right spot? sorry guys

[blind_elk]

What ECU are you using in this build?

[Jarrrrrrrrrrod]

I'm using a stock rb25det auto ecu, but my transmission is 5 speed.

[Plattsy]

I'm using a stock rb25det auto ecu, but my transmission is 5 speed.

plumb back bov, or get manual ecu

[Jarrrrrrrrrrod]

if anyone's interested, I have blocked off the bov with a coke can gasket and it's hasn't help much. I did however find that my tps was missing one the two bolts that get undone when adjusting the sensor.