RB25 Idling way to high

[Darth & Vader]

Hey Guys, just getting around to finishing up my build and was anxious to see if she would start, so i fired her up! Runs well, but the only problem im having is that my idle is about 3-4k (so the cluster says). Waiting for my air filter to arrive so i started it up without a filter on the end of the MAF. Would that be the problem? I didn't have another to check with so couldn't test it out myself.

S1 RB25
Q45 TB w/ TPS

I've tried adjusting the screw on the IACV but it didn't do anything.

Thanks for the help.

[b00stinbmx]

i made the same problem too bro, you have to remove the coolant fast idle mechanism from the q45 tb, cause right now your throttle is actually cracked a little. serach it online and you'll find out what im talking about, once you do that it'll idle normal around 1200 till warm up then 800ish at normal operating temp, might have to do some adjustments with the iacv and make sure your timing is set correctly as well.

[Darth & Vader]

i made the same problem too bro, you have to remove the coolant fast idle mechanism from the q45 tb, cause right now your throttle is actually cracked a little. serach it online and you'll find out what im talking about, once you do that it'll idle normal around 1200 till warm up then 800ish at normal operating temp, might have to do some adjustments with the iacv and make sure your timing is set correctly as well.

Hrmm....I looked at my Tb and i don't see the little "plunger" that the i believe you were thinking of is saying to remove. Here is a pic of my Tb.


http://i1084.photobucket.com/albums/j401/rb24s14/Parts4sale024.jpg

[Sileighty_85]

Tach is gonna be wrong, needs to be recalibrated

either Vac leak or cable is too tight causing the TB to be cracked open.

usually the first start up is gonna idle kinda high maybe 1500-1800 but should die down after a few mins

[Darth & Vader]

Tach is gonna be wrong, needs to be recalibrated

either Vac leak or cable is too tight causing the TB to be cracked open.

usually the first start up is gonna idle kinda high maybe 1500-1800 but should die down after a few mins

I'll make sure to check both of those. I'll get back to you in the morning.

Thanks for your help.



UPDATE: Checked the cable and it closes all the way. I guess I'll have to do a boost leak test.

If for some reason the purple plug on the IACV wasnt making a good connection, would it act like this?

[Darth & Vader]

No boost leaks on my system! It's like cruise control all the time! :bite:

[Sileighty_85]

did you plug the Vac ports on the under side of the Intake Manifold?

[Darth & Vader]

did you plug the Vac ports on the under side of the Intake Manifold?

Not all are plugged.
1 and 2 are plugged
3 is vacuum for FPR
4 is vacuum for BOV

and wastegate actuator is straight to hotpipe nipple.

[240sxrb25]

Q45 tb has a high idle adjuster deal on it to enhance warmup on the automatic q45's but that wont cause that big of an idle issue. Maybe 500rpm in some cases. Check all injector grommets for vacuum/boost leaks too. Check idle air control phillips screw and also the flat head throttle plate adjustment( kinda tough to reach but its underneath there somewhere)

[Darth & Vader]

Q45 tb has a high idle adjuster deal on it to enhance warmup on the automatic q45's but that wont cause that big of an idle issue. Maybe 500rpm in some cases. Check all injector grommets for vacuum/boost leaks too. Check idle air control phillips screw and also the flat head throttle plate adjustment( kinda tough to reach but its underneath there somewhere)

Odd! I've checked the IACV philips screw and it did nothing. Do i have to have unplug the TPS THEN mess with the screw? I had the TPS connected and car was on while i was adjusting iacv screw and it was having no effects what so ever.

I will also check the injector grommets as well since i had JUST put the stock injectors back into the greddy intake and it was a PAIN getting the gromets in as well as the injectors into the grommets!

The puple iacv plug sort of snapped when trying to put it on and im thinking of the wires is not making a great connection since it broke at the connector...Would it cause it to be acting this way if it werent making a connection?

Thanks.

[Darth & Vader]

Disconnected the MAF while the car was running and it completely died! I thought it should still run, just not idle or rev past 2500.

I hope to get this fixed, it sucks :(

Thanks

[Sileighty_85]

IACV might be stuck open, Pull it off and blast it out with some MAFS cleaner

the Purple plug is the idle up for the A/C so its not really needed and shouldnt affect unless the A/C button works.

engine should still run might have to blip the throttle to keep it alive if you unplug it while its running.

[Darth & Vader]

IACV might be stuck open, Pull it off and blast it out with some MAFS cleaner

the Purple plug is the idle up for the A/C so its not really needed and shouldnt affect unless the A/C button works.

engine should still run might have to blip the throttle to keep it alive if you unplug it while its running.

The AC button DOES work. Tho i do not have AC in my car, the unit itself does actually work & it is always pushed in. :o

I will remove the IACV this weekend and blast it out. I really appreciate the help man.

[Sileighty_85]

well if the A/C button works and lights up and the purple plug is in then the idle will raise to compensate for the load being put on the engine. Just unplug the purple plug

[Darth & Vader]

Well, here is a video of my engine idling at around 3500-4000RPM.....
I have checked to make sure the TB is shutting all the way and that the cable is loose.
I've tried adjusting my IACV with the TPS disconnected and nothing is changing.

Would me not having an oil catch can hooked up be causing my engine to idle this high? I'm really tired of trying to figure this out....

http://i1084.photobucket.com/albums/j401/rb24s14/th_Parts4sale025.jpg (http://s1084.photobucket.com/albums/j401/rb24s14/?action=view&current=Parts4sale025.mp4)

[Sileighty_85]

Vids not working for me (maybe cuz work PC)

But it really sounds like youe having a Vac leak on the Intake Manifold.

check all the ports on that thing.

there should be 6 ports IIRC theres a really big one for the PCV valve under the IAVC
http://www.enjukuracing.com/isis-intake-manifold-nissan-rb25det-pi-8596.html

[Sileighty_85]

That Vac port on the top left side of the TB is open , you need to plug that one as well

Also check the little allen screw adjuster maybe whoever modded it maladjusted it
http://i73.photobucket.com/albums/i235/Neil_85/Miyukis%20Silvia/DSCN5318.jpg

Check to see if the TB is actually completely closed
http://i73.photobucket.com/albums/i235/Neil_85/Miyukis%20Silvia/DSCN5319.jpg

[Darth & Vader]

That Vac port on the top left side of the TB is open , you need to plug that one as well

Also check the little allen screw adjuster maybe whoever modded it maladjusted it
http://i73.photobucket.com/albums/i235/Neil_85/Miyukis%20Silvia/DSCN5318.jpg

Check to see if the TB is actually completely closed
http://i73.photobucket.com/albums/i235/Neil_85/Miyukis%20Silvia/DSCN5319.jpg

It's the middle yellow marked one correct? I will most def check that out as well as plugging up that port.