RB25 Idle problem!

[banshee_rider909]

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]

really?? nobody can help me out?

[NismoPlsr]

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

[fliprayzin240sx]

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]

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]

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]

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]

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]

Check the ECU for codes. Could be CLT sensor.

[banshee_rider909]

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]

Sounds crazy but did you check your coolant lately.

[banshee_rider909]

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]

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