RB25 Idle problem! - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

banshee_rider909 · 06-19-2013, 02:24 AM

ok so i have a rb25 swap in my s14 and everytime i start it (from a cold start) it won't start unless i step on the gas a bit. Now once it turns on, it tries to catch idle. It begins to rev up and down until it gets warm. once the motor is warm and i rev it the rpm will come all the way down (almost shutting off) and rev up and down by itself untill it can catch idle. Car idles fine when its warm, but as soon as i let off the gas quickly it tries to find warm idle....i have a feeling its the idle air control valve(IAVC) but just want others opinions before i make a final conclusion.

banshee_rider909 · 06-20-2013, 11:53 AM

really?? nobody can help me out?

NismoPlsr · 06-20-2013, 02:20 PM

You running q45 throttle body? If so, did you disable the built in cold idle throttle up?

*fliprayzin240sx* · 06-20-2013, 02:22 PM

Mine was doing this but I cheated the IACV. There should be a small adjustment screw on the TB that would crack the butterfly just enough for it to have a stable idle.

Ka-t in progress · 06-20-2013, 05:55 PM

Make sure your maf is at leasts 12 inches from the turbo,and that there is a major bend in the piping. Ran into the same problem

banshee_rider909 · 06-20-2013, 06:36 PM

Quote:

Originally Posted by NismoPlsr

You running q45 throttle body? If so, did you disable the built in cold idle throttle up?

No I'm running stock throttle body

banshee_rider909 · 06-20-2013, 06:38 PM

Yeah I've messed with the screw but no matter what, it will idle up and down. It will find steady idle if I open it up all the way but it stays idling at high rpm

Yeah the maf is 12 inch from the turbo with a 90degree bend

OBEEWON · 06-21-2013, 06:44 AM

What intake manifold do you have?
Make sure the hose that bypasses the throttle body isn't kinked. I had that issue until I re-routed the hose.

OnTheChip · 06-21-2013, 09:45 AM

Check the ECU for codes. Could be CLT sensor.

banshee_rider909 · 06-22-2013, 01:57 AM

Quote:

Originally Posted by OBEEWON

What intake manifold do you have?
Make sure the hose that bypasses the throttle body isn't kinked. I had that issue until I re-routed the hose.

Idk what hose your talking about lol ill post pics of the engine set up in the morning. It's all stock (including stock manifold)

MADE · 06-22-2013, 07:34 PM

Sounds crazy but did you check your coolant lately.

banshee_rider909 · 06-27-2013, 12:41 PM

Quote:

Originally Posted by MADE

Sounds crazy but did you check your coolant lately.

what does coolant have to do with this...

so i see that some of my vacumm lines are pluged up and a line that goes into the stock charger pipe isn't even on there...could that affect it?

driftinCleen · 06-29-2013, 07:00 PM

leaks will definitely cause for crappy idle and run out of tune. and with rb25 yes coolant level matters

06-19-2013, 02:24 AM	#1
banshee_rider909 Zilvia Addict Join Date: Oct 2011 Location: Inland Empire Age: 32 Posts: 812 Trader Rating: (15) Feedback Score: 15 reviews	RB25 Idle problem! ok so i have a rb25 swap in my s14 and everytime i start it (from a cold start) it won't start unless i step on the gas a bit. Now once it turns on, it tries to catch idle. It begins to rev up and down until it gets warm. once the motor is warm and i rev it the rpm will come all the way down (almost shutting off) and rev up and down by itself untill it can catch idle. Car idles fine when its warm, but as soon as i let off the gas quickly it tries to find warm idle....i have a feeling its the idle air control valve(IAVC) but just want others opinions before i make a final conclusion. __________________ MmmmmmTACOS

06-20-2013, 11:53 AM	#2
banshee_rider909 Zilvia Addict Join Date: Oct 2011 Location: Inland Empire Age: 32 Posts: 812 Trader Rating: (15) Feedback Score: 15 reviews	really?? nobody can help me out? __________________ MmmmmmTACOS

06-20-2013, 02:20 PM	#3
NismoPlsr Zilvia Addict Join Date: Apr 2003 Location: CT Age: 41 Posts: 690 Trader Rating: (21) Feedback Score: 21 reviews	You running q45 throttle body? If so, did you disable the built in cold idle throttle up? __________________ S12 \|\| KN13 \|\| S13 \|\| B16

06-20-2013, 02:22 PM	#4
fliprayzin240sx Man w/ CTSV & a Car Seat Join Date: Aug 2002 Location: Tampa Posts: 17,998 Trader Rating: (19) Rides Gallery: fliprayzin240sx Feedback Score: 19 reviews	Mine was doing this but I cheated the IACV. There should be a small adjustment screw on the TB that would crack the butterfly just enough for it to have a stable idle. __________________ If you think Zilvia has too many assholes... CLICK HERE!!!

06-20-2013, 06:38 PM	#7
banshee_rider909 Zilvia Addict Join Date: Oct 2011 Location: Inland Empire Age: 32 Posts: 812 Trader Rating: (15) Feedback Score: 15 reviews	Yeah I've messed with the screw but no matter what, it will idle up and down. It will find steady idle if I open it up all the way but it stays idling at high rpm Yeah the maf is 12 inch from the turbo with a 90degree bend __________________ MmmmmmTACOS

06-20-2013, 05:55 PM	#5
Ka-t in progress Leaky Injector Join Date: Oct 2012 Location: Middle tennessee Age: 36 Posts: 89 Trader Rating: (0) Feedback Score: 0 reviews	Make sure your maf is at leasts 12 inches from the turbo,and that there is a major bend in the piping. Ran into the same problem

06-21-2013, 06:44 AM	#8
OBEEWON Post Whore! Join Date: Feb 2006 Location: Hightened State of Emergency Posts: 6,054 Trader Rating: (9) Feedback Score: 9 reviews	What intake manifold do you have? Make sure the hose that bypasses the throttle body isn't kinked. I had that issue until I re-routed the hose. __________________

06-21-2013, 09:45 AM	#9
OnTheChip Zilvia Junkie Join Date: May 2013 Location: Burgaw, NC Posts: 318 Trader Rating: (0) Feedback Score: 0 reviews	Check the ECU for codes. Could be CLT sensor. __________________ NismotronicSA - Speed-Density Tuning for Nissans

06-22-2013, 07:34 PM	#11
MADE Zilvia Addict Join Date: Jan 2006 Location: Norf Norf Posts: 974 Trader Rating: (1) Feedback Score: 1 reviews	Sounds crazy but did you check your coolant lately. __________________

06-29-2013, 07:00 PM	#13
driftinCleen Join Date: Jun 2013 Location: flo-rida Posts: 19 Trader Rating: (1) Feedback Score: 1 reviews	leaks will definitely cause for crappy idle and run out of tune. and with rb25 yes coolant level matters