High Idle on Rb25det

[240sxed]

After putting on my greddy intake manifold, it seems I have an unusually high idle, sometimes at around 1800-1900 rpms. It there always when its cold, but sometimes when its warm it will also be idling high. And sometimes it feels like 1000-1200, then sometimes its about 800-900, but i've never gotten it to go back to 650-700 like stock? Any ideas? There doesn't seem to be any boost leaks or they're miniscule, The car never dies out, could it be a boost leak? or is it an IACV IAV issue maybe?

[AxiOn419]

Exact same problem but with an rb20det, any ideas?

['90_240sx_Lover]

just a guess, the computer could be sending more fuel becuase it senses more air coming in more freely. Just an idiot guess. Lol, adjust the idle screw

[narfdanarf]

the smallest hole or crack in the intake system, anywhere past the TB will cause the car to idle high, and will also make it harder for your turbo to spool and it will be less efficient. Just make sure the gaskets are all on and you got everything tight.

A piece of the gasket came out of the intake on my talon and it idled at like 2200-2500, and it wasn't very big at all.

[240sxed]

Hmmm but sometimes it idles almost normal?

Also... it wouldn't cause my car to die out ? or is that if its before the throttle body?

[GTR Shop]

My $$ is on airlead.. Spray CRCof similar at all flanges and joints etc and see where th idle rises.

[narfdanarf]

Yeah, sometimes my talon would idle around 1200, but it would go up to 2500 at other times too.

I agree with GTR shop, spray some Carb cleaner around the IM and see if the idle jumps up for a second. That will tell you were the leak is.

[goofynick6]

Check the TPS if you messed with it at all. If the idle switch isn't making a connection it will idle high and want to stall out..

Nick

['90_240sx_Lover]

My car's rpm jump around when i turn the a/c on

[240sxed]

Check the TPS if you messed with it at all. If the idle switch isn't making a connection it will idle high and want to stall out..

Nick

It idles high but never wants to die out/stall out

Other thing is its hard to tell/hear the motor since it revs at like 1800 so, Its hard to hear for vac leaks and listen for motor rev change.

Idle adjustment screw, on the ecu and on the AICV valve? or is it the air something or other valve, theres two of um, one on the manifold, and one below.

[Slo_240sx]

Sounds like a simple vaccum leak. ECU will readjust back and fourth to try to get the mixture perfect, but theres a leak so it will fluctuate. Spray carb clean and check all vaccums lines for destination and cracks or rubs.-Alex

[240sxed]

Sounds like a simple vaccum leak. ECU will readjust back and fourth to try to get the mixture perfect, but theres a leak so it will fluctuate. Spray carb clean and check all vaccums lines for destination and cracks or rubs.-Alex

I've done a quick spray today, but it revealed nothing... The idle is constant, like my boost pressure doesn't vary, niether does the needle. It stays at whatever high idle its at. Usually inbetween lights when the needle comes back down after Im breaking is when it changes, its not like the thing is stuttering. Usually im pretty good about finding vac leaks.

[cvc9216]

are you using a q45 TB? pull the fast idle system off the TB. do you have coolant hoses hooked up to the TB? I'm guessing no?

[240sxed]

are you using a q45 TB? pull the fast idle system off the TB. do you have coolant hoses hooked up to the TB? I'm guessing no?

Yeah I am using the Q45 TB, Im not sure what the fast idle system is?

I do not have the coolant hoses hooked up, greddy's diagrams show that it does'nt need to be hooked up. The coolant passages that used to go up to the manifold have "plugs that you put in them" ?

[240sxed]

Anybody?

[9240sx]

Sounds like a TPS problem to me.

[240sxed]

Sounds like a TPS problem to me.

Switched the RB tps onto the q45 one...same issues...

[cvc9216]

remove this arm and spring (circled) from the TB that the plunger pushes on (arrow). that will fix it I promise

[240sxed]

remove this arm and spring (circled) from the TB that the plunger pushes on (arrow). that will fix it I promise

cool...im guessing it has something to do with the coolant heating the spring and...it becomes less/more tense causing the little thing that would be at "0" percent throttle to stay at 1 or 2 percent?

Gonna check it out 2m.

[240sxed]

fixed that problem nicely.

[KoshiLe]

i took off the spring, did spray test, and still have a high idle. I believe it might be electrical? Because i only have one of the two harnesses from RB25 SII hooked up to the Q45 TB.

Any Ideas?

[marshallpre1]

Bump. Maybe when it's warming up I have the similar issues.. Sometimes it will idle for 20 minutes @ 1500-2000rpm before it starts hovering around 1100 rpm. Sometimes it drops to 700 rpm sometimes not, very very weird. However, I only have the stock manifold...

[marshallpre1]

Fixed mine. Found a loose hose... Tightened and now fixed...