High Idle

[JustinP]

Is this because the carby cleaner is eating the seals for the butterfly shaft? If so thanks for the heads up as I was about to clean mine out in a similar fashion! Although mine is a RB25 Neo so not sure if the single butterfly (and TCS one) is different to the ITB's on the RB26.

Did u clean the throttle bodies with carby cleaner? I did this to my 1st rb26 and had similar symptoms. I had to replace the throttle bodies.

Check there is no air leaks at the throttle bodies either. Can also try blocking the idle control valves air pipe. If it idles fine then u need a new idle control valve.

Last but not least disconnect all of the throttle linkages from the main linkage and see if the idle is fixed they might be over adjusted

[rondofj]

I was just guna create an idle related topic then saw this.. My problem is a high idle of 1200-1400rpms, mostly 1400rpms upon startup esp when its cold. It takes its time, roughly 10mins or so, or even more once the motor has warmed up before it reaches 800rpms. Quite annoying, this is not normal, is it?

Done quite a few searches. Pointers are clean aac(is this also called the idle control valve?), clean afm, check for vac leaks ( how do i do this?), and now im readin bout tge idle air regulator thingy? I know mines temp related, can anyone please advise??

[rondofj]

The engines the rb25det neo

[Jap_Muscle]

Air is getting in there somehow, 2min and a set of long nose pliars, squeeze the hoses to the plenum. Could be a brake booster, clutch booster, pcv, charcoal canister, or one of the two idle control motors.

We have already pressure tested the inlet side and there is no leaks what so ever. But from what others have said it may be one of the other things u mentioned.

Is this because the carby cleaner is eating the seals for the butterfly shaft? If so thanks for the heads up as I was about to clean mine out in a similar fashion! Although mine is a RB25 Neo so not sure if the single butterfly (and TCS one) is different to the ITB's on the RB26.

Its only a issue if you dont re-coat the shaft with throttle paste. In my case we completely striped the throttle bodies back to make sure it was completely clean and then added 3 coats of Tomei Throttle Coat. This should have solved the problem, if it was just that.

I was just guna create an idle related topic then saw this.. My problem is a high idle of 1200-1400rpms, mostly 1400rpms upon startup esp when its cold. It takes its time, roughly 10mins or so, or even more once the motor has warmed up before it reaches 800rpms. Quite annoying, this is not normal, is it?

Done quite a few searches. Pointers are clean aac(is this also called the idle control valve?), clean afm, check for vac leaks ( how do i do this?), and now im readin bout tge idle air regulator thingy? I know mines temp related, can anyone please advise??

Yes the AAC is the idle control valve.

As for checking for vac leaks, You have to block off your entire inlet side and then stick a pressure valve inside somewhere and test if it is leaking.

In my scenario its not related to AFMs as im running a mafless ecu.

[SargeRX8]

I was just guna create an idle related topic then saw this.. My problem is a high idle of 1200-1400rpms, mostly 1400rpms upon startup esp when its cold. It takes its time, roughly 10mins or so, or even more once the motor has warmed up before it reaches 800rpms. Quite annoying, this is not normal, is it?

Done quite a few searches. Pointers are clean aac(is this also called the idle control valve?), clean afm, check for vac leaks ( how do i do this?), and now im readin bout tge idle air regulator thingy? I know mines temp related, can anyone please advise??

Pretty sure around 1200 on cold start is perfectly normal while its warming up. Skylines take close to 8 - 12 minutes to warm up to operating temperature, even more in cold nights. Winter nights I drive back from work to home at 12am. Cold nights, the car didn't even hit 60degrees after 15minute drive.

Is a vacuum leak the opposite on a mafless setup? Ive got an AFM and if I have a vac leak, my idle is f**king low as shit, timing gets thrown out and its lumpy as arse shit.

What I would do is disconnect everything connected to the TB using a vacuum signal(as long as they aren't necessary, the car will still operate). Or just go around the engine bay pinching thin hoses. If there is a vac leak before the map sensor, will it throw out the reading? Or only a vac leak after the map sensor? Ive never had any experience with a map based car. One would assume that if there is an issue behind the map sensor it will cause problems, after maybe not. But again, I have no idea in this field.

Silly question but is your idle tune setup right? My idle tune when I am running my air conditioner results in my car idling close to 1500rpm randomly lol.Also I too have noticed, not only in my car but in a few Ive driven(manual, and not only skylines), that when you are driving and you clutch in, the idle seems higher than when the car is motionless. I have NO idea why this is. My car will idle close to 900 - 1000rpm when I clutch in then drop down to about 750 when I stop.. Its weird but meh.

Edited September 28, 2011 by SargeRX8

[rondofj]

Yep mine does the same, idle drops a bit when I clutch in esp on a cold engine, it drops more, it normally idles to 1400, when i clutch in then it goes to 800, ut if the engines been warmed up it usualy stays at 800rpms, still think my idles a bit high at 1200-1400 cold.. What do I do lol.. Yep at least 10mins seems a long time for the idle to become 'normal'... Dont know about my idle tune, have to ask JEZ on that one..

On a different note, I need an O2 sensor for my R34 (I will get a mild steel JJR dump/front onto which it will sit).. Does anyone know if I should get the one from Kudos Motorsport (its says for R32 and R33 only so..??) or just get a Ford EL Falcon one from Bursons or Repco / Supercheapy..?? I read that I will ned a plug convertor for it to fit onto my factory wiring but forgot which one..

[SargeRX8]

Yep mine does the same, idle drops a bit when I clutch in esp on a cold engine, it drops more, it normally idles to 1400, when i clutch in then it goes to 800, ut if the engines been warmed up it usualy stays at 800rpms, still think my idles a bit high at 1200-1400 cold.. What do I do lol.. Yep at least 10mins seems a long time for the idle to become 'normal'... Dont know about my idle tune, have to ask JEZ on that one..

On a different note, I need an O2 sensor for my R34 (I will get a mild steel JJR dump/front onto which it will sit).. Does anyone know if I should get the one from Kudos Motorsport (its says for R32 and R33 only so..??) or just get a Ford EL Falcon one from Bursons or Repco / Supercheapy..?? I read that I will ned a plug convertor for it to fit onto my factory wiring but forgot which one..

f**k the Ford sensor. It did not work for me. Throws out the tune so we disabled it. Even tuning the car around it gives poor results. The piece from kudos isn't expensive only about twenty extra or some shit.

[rondofj]

I know but the kudos sensor says for R32 and 33 only, hope the R34 uses the same threaded plug. Anyone tried this on their 34? Im gettin a JJR dump/front pipe for the R 34 but assume the 33 one is exactly the same item?

[SargeRX8]

I know but the kudos sensor says for R32 and 33 only, hope the R34 uses the same threaded plug. Anyone tried this on their 34? Im gettin a JJR dump/front pipe for the R 34 but assume the 33 one is exactly the same item?

Fairly sure it is the same. Isn't the jjr dump the same for all models?

[mico]

hey ive got one of those valves if u need it.

[rondofj]

Which valve, u mean the O 2 sensor?

[Don Dada]

Could you elaborate on exactly what the cold start valve is? Are you referring to the "Idle Control Regulator" part no = 22660-01U10?

this thing here?

Yes this....

If you said you resealed the TBs and have the same problem, you should definitely look at this.

[Jap_Muscle]

Yes this....

If you said you resealed the TBs and have the same problem, you should definitely look at this.

Looks like its the next logical move.

Ill check back when i have an update

[paulr33]

djetro gtr - are your 02 sensors plugged in? are they working? if they arent connected or mangled disable 02 feedback

also do you have IDLE-IG under FUNCTION SELECT? try using that

[paulr33]

but as adriano said, its more likely a vac leak in the rubber vac lines

this stuff is as old as the car and is prone to splits and cracks etc which cause wonky idea

2 minutes with some plies and youll nuke the high idle

[Room42]

Also I too have noticed, not only in my car but in a few Ive driven(manual, and not only skylines), that when you are driving and you clutch in, the idle seems higher than when the car is motionless. I have NO idea why this is. My car will idle close to 900 - 1000rpm when I clutch in then drop down to about 750 when I stop.. Its weird but meh.

It does this because the gearbox is still spinning and the clutch grabs a bit and 'helps' the engine spin.

Rondofj yours is definitely the aac. Pull it out, clean it and put it back in. I used clr clear. Adjust the screw so it reads the same rpm on your computer as your tacho.

To the OP, it has been said in this thread already but generally the only thing that will cause a high idle is an vacuum leak. This includes; incorrect throttle cable adjustment, incorrect idle screw adjustment, perished/broken intake gaskets, broken manual boost controller, dirty/incorrectly adjusted aac, perished injector O rings, cracked hoses, rooted brake booster, etc. The list goes on. Anywhere air can get in you should check. Use some engine starting spray to help you find the hole.

[Jap_Muscle]

djetro gtr - are your 02 sensors plugged in? are they working? if they arent connected or mangled disable 02 feedback

also do you have IDLE-IG under FUNCTION SELECT? try using that

Not sure if this is directed to me but,

There isnt a 02 Sensor on the car currently, and is something that is on the list to do. However i have already tried disabling the IDLE-IG and it does nothing. Even after letting it idle for 5minutes and warming up.

According to your FAQ paul,

The first step when installing the PowerFC is to let it idle for upto 30 minutes on your car so it adjusts to your engine setup. This includes turning on the Aircon, Demister and Heater throughout the idle stages so the ECU has time to learn the engine setup and idle levels. This can be done by doing an "initialize" on the PowerFC. This will reset all settings back to default (including your tune) and set the PowerFC back to learn mode (for idle only). You should not do this if you have a tune as there is no way to save the tune before it is erased. If you have datalogit or the FC Pro cable/software you can copy the maps. Preform the initialize and then reupload the maps. A few people have seen really screwey idle from the Hand Controller itself being plugged in. The workaround is to unplug the Hand Controller and it idle's normally. This is a very strange problem and certinaly not common. Initial suggestions would lead to an electrical problem somewhere? If you still stuck with a unstable idle, try the factory ECU and does the idle bug go away? If it is still present it could indicate a mechanical issue with the factory idle control (usually the AAC valve). You can reset the PowerFC to factory defaults to "re-learn" the idle control from scratch and this seems to fix most idle related issues, such as hunting at idle and also high RPM surge when coming off a gearchange or throttle acceleration.

Is it worth trying these things with a built motor? or is this only useful on a standard car?

but as adriano said, its more likely a vac leak in the rubber vac lines

this stuff is as old as the car and is prone to splits and cracks etc which cause wonky idea

2 minutes with some plies and youll nuke the high idle

Which lines spesifically would i be looking at clamping? (ignore the red arrow)

Also should the throttle sensor be showing ~0.36v at idle? shouldnt it be 0.0v? Possible TPS issue?

To the OP, it has been said in this thread already but generally the only thing that will cause a high idle is an vacuum leak. This includes; incorrect throttle cable adjustment, incorrect idle screw adjustment, perished/broken intake gaskets, broken manual boost controller, dirty/incorrectly adjusted aac, perished injector O rings, cracked hoses, rooted brake booster, etc. The list goes on. Anywhere air can get in you should check. Use some engine starting spray to help you find the hole.

• We replaced all the gaskets on the intake side including the throttle body shaft ones.
• Using a electrionic boost controller
• We did have a cracked O-Ring, but has been fixed.
• Replaced AAC

The car was originally tuned with the cracked O-Ring. Do you think its possible that because of the current tune with the cracked O-Ring, (even though it was replaced) would still cause a idle issue because the ECU has been tuned that way?

A re-tune is booked in regardless

Edited September 30, 2011 by Jap_Muscle

[Room42]

In no particular order; clamp any line that is coming off the intake manifold, the tps voltage is fine and no it should not be 0.0V mine is 0.34V, you will not need a tune just because of a cracked o ring, if you replaced the aac did you adjust the idle screw in it? Screw it all the way in and then bring it out half a turn at a time until the idle is correct. On another note I meant in my last post "throttle stop adjustment" not idle screw adjustment. You should not be touching the throttle stop screw and if you do then it will need to be reset with feeler gauges and the tps voltage checked. Be careful with using pliers on hoses as they can wreck them pretty easy. I prefer bending hoses but use a rag if you have to resort to pliers. There is stuff all that you can do in a tune that would make a car idle above about 1200 rpm. If you lean a car out at idle through the tune it will idle lower. Check that the boost controller is connected properly. It could suck air in through incorrect installation. Plenty of things it could be but I'm sure we'll get to them all and you'll get you car sorted.

[paulr33]

tps is ok as when its closed for idle, its 0.30v or thereabouts so thats ok

but i guess you need to ask yourself

when did this issue first start

has it started since youve made a ton of changes or has it started without any other changes - ie something has failed?

the ecu can only do what it can but the mechanical side of the engine always takes over (ie vac lines, misconfiguration, leaks etc)

[Rolls]

Have you simply tried adjusting the idle screw on the AAC valve? I know the 25s and 20s have one.