high idle of 1500rpm consistent?

Information on the naturally-aspirated KA24E and KA24DE engines.
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USMCgetsome
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high idle of 1500rpm consistent?

Postby USMCgetsome » Fri Jan 23, 2009 2:38 pm

Ok so i read the iacv sticky and dismantled and cleaned throughly. I then reassmbled and used a good rtv to seal it.

started car and it goes to 1500 still.

So then i pinched off the iavc hose at the intake. No change. I then pinch the smaller hose that goes to the intake manifold directly behind the throttle body. Viola my idle goes to 800rpm and stays consistent.

wtf does that mean? I did take off the throttle body and found that there was a small nipple that was not capped that led to the small hole which is right before the throttle plate.

I will post up results tomorrow. Thanks for reading and feel free to throw out ideas at me.

btw this is on my ka24de. not my rb25det


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USMCgetsome
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Re: high idle of 1500rpm consistent? (KUILLIN_DRIFTER)

Postby USMCgetsome » Fri Jan 23, 2009 5:29 pm

got 2 cel codes

infamous 34 and 41

34 knock

41 air temp sensor

think this is also causing an issue with my idle. ill have the throttle body installed tomorrow. update u fellas then.

NISSAN240SX12
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Re: high idle of 1500rpm consistent? (KUILLIN_DRIFTER)

Postby NISSAN240SX12 » Fri Jan 23, 2009 7:49 pm

im having the same issue. If i pinch the little tube going to the intake the rpms go down too. I jerry rigged mine up so it idles at 800 rpms. let me know how that turns out. thanks!

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Re: high idle of 1500rpm consistent? (NISSAN240SX12)

Postby USMCgetsome » Sun Jan 25, 2009 9:23 am

no change. Still idles at 1500 rpm. Did you get any cel? I don't think it's a vacuum leak. I need to pinch off that air regulator today. I'll post back up in a few.

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Gabes13
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Re: high idle of 1500rpm consistent? (KUILLIN_DRIFTER)

Postby Gabes13 » Sun Jan 25, 2009 12:57 pm

check your tps.

When my tps was no bueno I had some retarded high idles like that.

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Re: high idle of 1500rpm consistent? (pandapants)

Postby USMCgetsome » Sun Jan 25, 2009 4:38 pm

thanks for the info. I researched it as well and will trouble shoot it tomorrow.

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Re: high idle of 1500rpm consistent? (KUILLIN_DRIFTER)

Postby kpodj61240 » Sun Jan 25, 2009 11:42 pm

this may help you this may not. the guy that did my swap never hooked up the coolant lines on my iacv which was causing my high idle. because my car always thinks its trying to warm up when it already is. plus i cleaned my iacv. i just fixed this weekend i went from 1600 down to 880.

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USMCgetsome
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Re: high idle of 1500rpm consistent? (kpodj61240)

Postby USMCgetsome » Mon Jan 26, 2009 4:50 am

coolant line to iacv? The one i got doesn't have that at all. Mine doesn't even have that epoxied screw. I only have the idle screw and the 2 solenoids. Ohhh and that big vacuum hose.
Modified by KUILLIN_DRIFTER at 12:36 PM 1/26/2009

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USMCgetsome
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Re: high idle of 1500rpm consistent? (KUILLIN_DRIFTER)

Postby USMCgetsome » Mon Jan 26, 2009 11:21 am

ok scored me 2 used tps at the junk yard. No luck for a knock sensor. Going to ohm them out then attempt to install.

Also found that if i capped that smaller line that sits right behind the intake manifold my throttle sits at 700 rpm with the iacv fully closed.

Was running pig rich earlier but after driving it 30 miles today seems like the ecu corrected the fuel.

Now i figure this has to be an issue with the throttle body itself or tps.

Also, pinched off the air reg and no change. I pinched off the iacv line and barely a change like 100rpm gave it a little throttle and i can feel it stop sucking air. Any ideas?

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Re: high idle of 1500rpm consistent? (KUILLIN_DRIFTER)

Postby USMCgetsome » Tue Jan 27, 2009 12:04 pm

ok new tps installed and calibrated using volt/ohm meter to .50 volt. No change in status. I did notice that the crappy gasket maker i used is worthless. The throttle body has a good leak. Ordered new gasket kit. I'll keep you guys posted.

I did notice today that if i pinched the iacv hose that it did drop down in rpm today. Seems like it's responding now. but the little air hose next to it changes the idle drastically.


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Re: high idle of 1500rpm consistent? (KUILLIN_DRIFTER)

Postby USMCgetsome » Sat Jan 31, 2009 6:56 pm

did some cleaning and treating today. Cleaned connectors and pins for maf, tps, coolant temp sensor, pulled dizzy cap and cleaned the corrosion off the contacts. I see that my dizzy moved to a fully advanced position due to a crappy short bolt being installed.

My idle is now at 1100rpm. vacuum at 23hg. Running better but i'm still going to take the manifold apart. I saw some hose that were connected to the iacv metal tubing dry rotting.

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Re: high idle of 1500rpm consistent? (KUILLIN_DRIFTER)

Postby USMCgetsome » Mon Feb 02, 2009 8:20 pm

Found a good amount of discrepancies today.

Pcv valve = no bueno. Allowed a little bit of air back the other way.

Found some bolts loose on the intake manifold bolted to the head. Most were torqued but there was a few that were easy to remove(no torque, hand tight)

Plenty of caked sludge from a bad valve cover gasket leaking all over the intake side of the block. Cleaned it up throughly.

Found dry rotted hose on the pcv lines all 4 of them.

Iacv solenoid is no good. It's internals are not assembled correctly and not staying retained in the solenoid. The small black plum and spring fall out very easily.

Oil soaked harness for the iacv and knock sensor. gotta clean and treat.

taking apart the intake manifold next and cleaning up all the sludge. I'll keep ya posted. I do believe that the main reason for my bad idle is the air regulator and the iacv. Everything else looks ok.

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Re: high idle of 1500rpm consistent? (KUILLIN_DRIFTER)

Postby USMCgetsome » Thu Feb 19, 2009 4:22 pm

PROBLEM SOLVED! Replaced PCV valve. Also, replaced the hoses of the pcv system with new worm grove clamps.

Removed and tested both iacv and air regulator. Watched manually for the air reg to close with 12vdc applied and proper ohm resistance. Iacv also checked with 12vdc, ohms good, solenoid acutates properly.

Removed that iacv, air reg harness and cleaned and treated all connectors.

Replaced all vacuum hoses and worm groove clamps. Some had small cracks and splits also a little loose with those spring clamps.

Replaced intake manifold gaskets x2.

Started her up and she fires and idles at 750 rpm no adjustments made to iacv at all (fast idle screw is half way)

Fellas my idle problem was an air leak. Plain and simple. I just wonder which one of these fixes did the job.

My suggestion to all of you is to just do all that i did and replace all hoses and clamps and clean up that intake manifold.

Good luck!

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Re: high idle of 1500rpm consistent?

Postby 1990Poo40SX » Wed Feb 21, 2018 9:02 pm

I know this is a really old thread but thanks for this big write up!! I have a high idle and no matter how much I change the idle speed screw the idle doesn’t change, it’s not super high it’s about 1k but still annoying. I’m going to try all of this thanks for the ideas an things to check.


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