rb25 wont idle

[bkt808]

S1 rb25 mods are
arp head studs
greddy im
fmic
q45 tb
tomei fpr

the only way i can get it to idle somewhat is if i unscrew the iacv screw almost all the way out. then the idle will start to surge and some times it will stop surging and idle great for a few seconds then it goes right back to surging

has fuel pressure boosts fine, runs fine through all gears just the idle issue.

could someone explain to me what the air regulator does?

any help is appreciated thanks

[Dro]

Check your tps, if it's screwed up it will affect your idle.
What do you mean by a surging idle? Going from 300rpm to 1000rpm?

[2.5T_/<ouki]

I agree with above, try checking your TPS with a multimeter to make sure you're getting proper voltage. Also, make sure your coolant temp sensor is in working order.

I once had a problem like this and it turned out to be my MAF connection. It would make a good connection sometimes and work great under boost ECT, but would also just completely die on me and idle horribly. I had to open the MAF and resolder the pins inside.

GL!

[bkt808]

tps is set at .44v, yes surging like it wants to die. the only way it will stay running somewhat is if i have the iacv adjustment screw almost all the way out once i start to screw it in idle will drop surge for second and eventually just die.
vacuum leak?
what im thinking of is as im screwing the iacv screw in it causes more vacuum in the intake manifold there for sucking more air in from a leak somewhere. when the screw is almost all the way out there is less vacuum pressure on the leak/crack and the intake is getting its air through the iacv.

get what im saying? i know my grammar is cuckoo sorry guys!
any othe possibilties? iacv? cant be the air reg., it would cause a high idle correct?

edit: coolant temp is new, tried 2 different mafs both are good

[Dro]

Can you hear any leaks? Get a can of brake clean and start spraying your vac hoses to check for leaks.
Does the tps voltage change when you move the throttle? Try unplugging it and seeing how the car idles. Also see how it runs with the maf unplugged, if it doesn't change, try cleaning it.

[bkt808]

Can you hear any leaks? Get a can of brake clean and start spraying your vac hoses to check for leaks.
Does the tps voltage change when you move the throttle? Try unplugging it and seeing how the car idles. Also see how it runs with the maf unplugged, if it doesn't change, try cleaning it.

tps voltage does change, with the iacv screw almost all the way out i unplugged the tps, idle shot up to about 1500 - 2k then dropped to a surge again
i think i might hear a leak not sure though im going to try the starting fluid method

[PrimeDirective]

Is this a fresh build? Make sure its not something stupid simple like having two coil pack plugs switched.

[bkt808]

not a fresh build, is motorset from zerolift.

ok so i went to town on this motor with starting fluid and sure enough the injector to manifold o-rings were leaking pretty good so i tightened those up and pretty much idles excellent sometimes itll stumble a little coming down from revs, and hard starts are still an issue but other than that awesome.

!!!! next issue ive been having is this "toka toka toka grinding kind of sound"???? itll come for seconds up to a minute then go away and so on??? i dont think its rod knock cause as i increase revs it turns more into a grinding noise. kind of weird ill have to make a vid of it.
has anyone had a similar experience?

[fliprayzin240sx]

Take the IACV and clean it out. It might be sticking. Or you can cheat and eliminate it out completely. You can bump the idle up by cracking the throttlebody a bit. There should be a small screw/adjust that keeps the plate from closing all the way.

[bkt808]

Take the IACV and clean it out. It might be sticking. Or you can cheat and eliminate it out completely. You can bump the idle up by cracking the throttlebody a bit. There should be a small screw/adjust that keeps the plate from closing all the way.

i pretty much solved the idle issue being the injectors wasnt sealing good so now im rying to figure out this weird sound as described above