Jump to content
SAU Community

Recommended Posts

Hi All!

My GTR seems to be idling at 1150rpm, it is a stable idle and it is not idle hunting either. It has always done this since I purchased it. At first I thought it was a specifically tuned that way, but now I wonder?

Has anybody experienced this kind of situation before?

My GTR is pretty much stock with no boost modifications, and only a full Mine's exhaust system from the turbo-back.

I've read many threads on high idling, but none seem to put a finger on the situation.

Can anyone help me fix this problem? Could it be my AAC or something like that?

Any feedback will be much appreciated!

Link to comment
https://www.sau.com.au/forums/topic/118737-r32-gtr-high-idle/
Share on other sites

I've also been looking at some other skyline forums. Other GTR owners seem to speak about the same problem as well.

I've read threads indicative of aac problems, timing problems, afm problems and even wiring problems!

But all of them are just speculative. There were no real solutions.

I've checked my engine bay for cracked or broken off vacumm lines and the such, but I don't want to pull

anything apart until I've found some actual information on what is causing the high but stable idle.

I wonder if it could be the connector on the aac? I heard if you remove it, it could stabilise the idle.

*BTW: for those in the new, AAC stands for auxillary air control valve.

My idle is the same.

I suspect the car previously ran an aftermarket ECU but was returned to stock on export. Do you guys both have stock ECUs? What I'm getting at is could the switch back to stock reset the idle to a safe default of ~1200rpm and then it should be adjusted using the trim pot on the ECU?

I have just exchanged AFMs for two working units and the consult display indicates they are operating normally.

My AAC valve reads a constant 2%? Is that normal? My TPS is around 0.44V at idle. I'll double check that TPS but pretty sure that's what it read this morning on the way to work.

I'm keen to sort this out too. :no:

make sure the carbon canster connections (behind the lhs front headlight) are on properly and the right way around, i had this problem in my gt-r.. try blocking them both off ( from the engine) to see if that lowers the idle.

Hey all,

Sorry for the late reply! Work has been time consuming.

My ECU is stock, but I'll give the methods posted a try. Thanks!

Also, I realised that that my idle is at 1150rpm when the engine is running at optimal temp, from a cold start it idles at about 1000rpm.

I went to Hypertech Motorsports near where I live, and asked them for advice. The guy I spoke to said that you could fix the idle by resetting the idle stepper motor or something. I wonder what he was talking about?

But I'll get it checked out for sure.

Also, I will be resetting my ECU soon: Will give all of you the heads up on what happens.

Cheers all!

Mine is the same (32 GTR) nice smooth 1100 rpm idle......

I was told by tuning shop this is a common problem and is an air leak into the inlet manifold caused by old inlet manifold gaskets, it can be fixed by replacing the gasket but is time comsuming and costly...hence I live with the high idle.

BTW, Drops to 950 with AC on.

mine used to idle at 1400 warm so I got the shits with it and adjusted the flat head screw that is in the front of the idle air control valve. Screw it in, out and you will see RPM raise or lower. Now mine is around 950-1000RPM.

Hey all,

I reset my ECU the other day, a noticeable difference in drivability and power delivery, but no effect on the idle problem.

Went to Dr. Drift today, even he could not diagnose the problem. Had my GTR on diagnostic software, every setting was perfect from AAC response to TPS diagnosis. We experimented by lowering and increasing the AAC controller from the computer, we also switched tps off for troubleshooting purposes. But besides that all settings were nominal/optimal.

Came to a couple of conclusions:

1. Vacuum leak somewhere.

2. Throttle (inner and outer spacing gaskets) on the plenum, are somehow worn or even broken resulting in additional amount of external air being sucked in to the engine, which is not being detected by the AFM.

3. Throttle control arms are not set correctly, or have been deliberately set, to open slightly at idle rpm, but I don't think so: seem to be shutting fully.

4. ECU tuned setting: But Dr. Drift said it should be irrelevant according to software diagnostics.

I am going to check the pressure canisters at the front like 'blur' suggested.

Besides that I am going to take my car to the GTR pro's on tuesday at Hypertech Autosports, I hope GTR builder Eric Schlifelner, may help shed some experience on this problem. Because at the moment I am lost!

If anybody has any info on this, pls share. It will be much appreciated!

Cheers SAU!

Thanks dude. I was hoping my AAC was incorrect and it'd explain my 1200rpm idle.

Cheers

Yeah I'll let everybody know about the idle, when I take it in on Tuesday. I'll be pulling the plenum off and possibly removing the engine in order to cover every angle.

Sigh....got to take it in very early (all day job), should be fun though. Will be checking the ECU mapping very carefully as well, just to make sure it hasn't been re-flashed in japan.

Cheers!

  • 4 weeks later...

I’ve had a very similar problem with a 1100rpm idle.

This is really starting to annoy me as I recently pulled the complete intake manifold and throttle bodies off to inspect and fix any suspect components, but on reassembly still have the same high idle.

I found the Air Bypass Valve was seized. So I opened it and fixed it where with a 12v input it closed within the factory recommended time. The AAC spring was shagged. I destroyed the plug on the AAC while opening it and had another made. I checked all hoses for cracks and cleaned all components including the throttle bodies. The throttle body gasket did seem to be worn, so I replaced all gaskets. The timing is right, the consult reports that all signals are within factory specs but it still idles at 1100rpm.

This is so frustrating. I’ve also tried three different EPROM’s with no change in idle.

For those of you wanting to test some of the components on the GTR. At the back and underneath the inlet manifold you will see three hoses. The first is the supply to the AAC valve and the second is the supply to the Air Bypass valve. Disconnecting these and plugging them will effectively remove both the AAC and Air Bypass Valves from the idle equation. Blocking the feeds to the CC is also easily done. From there it becomes more difficult as all the hoses that may be causing the leak into the idle control chamber are all hidden under the intake manifold. I’ve had the whole lot apart and still can’t find what’s causing this. I’ve also tried removing the throttle body rose jointed arms so the individual throttles were completely closed, of course with no improvement.

As far as I can see it needs to be a leak in the system somewhere, bypassing air around the throttle bodies, but I certainly can’t find it. Under the intake manifold there are two major feeds that bypass the throttle and are connected to an ‘air bypass chamber’ of sorts. Branching off from this chamber is a myriad of hoses that provide vacuum and idle control functions. Blocking these two major feeds would prove or disprove a vacuum leak, but it involves removing the intake manifold and throttle bodies which is a lot of work to simply test a theory.

At this point I’m going to live with it as I’ve had the car in the shed for too long. I hope someone gives this a go at some point to see what happens.

geez, i wish i had to put up with an idle of 1100 rpm, that would be lovely :teehee:

instead, my warm idle is 1800rpm haha..still havnt found the leak yet or faulty AAC valve

plus side is, its quite easy to engage the twin plate because the car will start to drive when i slowly let out the clutch haha :ermm:

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • Power is fed to the ECU when the ignition switch is switched to IGN, at terminal 58. That same wire also connects to the ECCS relay to provide both the coil power and the contact side. When the ECU sees power at 58 it switches 16 to earth, which pulls the ECCS relay on, which feeds main power into the ECU and also to a bunch of other things. None of this is directly involved in the fuel pump - it just has to happen first. The ECU will pull terminal 18 to earth when it wants the fuel pump to run. This allows the fuel pump relay to pull in, which switches power on into the rest of the fuel pump control equipment. The fuel pump control regulator is controlled from terminal 104 on the ECU and is switched high or low depending on whether the ECU thinks the pump needs to run high or low. (I don't know which way around that is, and it really doesn't matter right now). The fuel pump control reg is really just a resistor that controls how the power through the pump goes to earth. Either straight to earth, or via the resistor. This part doesn't matter much to us today. The power to the fuel pump relay comes from one of the switched wires from the IGN switch and fusebox that is not shown off to the left of this page. That power runs the fuel pump relay coil and a number of other engine peripherals. Those peripherals don't really matter. All that matters is that there should be power available at the relay when the key is in the right position. At least - I think it's switched. If it's not switched, then power will be there all the time. Either way, if you don't have power there when you need it (ie, key on) then it won't work. The input-output switching side of the relay gains its power from a line similar (but not the same as) the one that feeds the ECU. SO I presume that is switched. Again, if there is not power there when you need it, then you have to look upstream. And... the upshot of all that? There is no "ground" at the fuel pump relay. Where you say: and say that pin 1 Black/Pink is ground, that is not true. The ECU trigger is AF73, is black/pink, and is the "ground". When the ECU says it is. The Blue/White wire is the "constant" 12V to power the relay's coil. And when I say "constant", I mean it may well only be on when the key is on. As I said above. So, when the ECU says not to be running the pump (which is any time after about 3s of switching on, with no crank signal or engine speed yet), then you should see 12V at both 1 and 2. Because the 12V will be all the way up to the ECU terminal 18, waiting to be switched to ground. When the ECU switches the fuel pump on, then AF73 should go to ~0V, having been switched to ground and the voltage drop now occurring over the relay coil. 3 & 5 are easy. 5 is the other "constant" 12V, that may or may not be constant but will very much want to be there when the key is on. Same as above. 3 goes to the pump. There should never be 12V visible at 3 unless the relay is pulled in. As to where the immobiliser might have been spliced into all this.... It will either have to be on wire AF70 or AF71, whichever is most accessible near the alarm. Given that all those wires run from the engine bay fusebox or the ECU, via the driver's area to the rear of the car, it could really be either. AF70 will be the same colour from the appropriate fuse all the way to the pump. If it has been cut and is dangling, you should be able to see that  in that area somewhere. Same with AF71.   You really should be able to force the pump to run. Just jump 12V onto AF72 and it should go. That will prove that the pump itself is willing to go along with you when you sort out the upstream. You really should be able to force the fuel pump relay on. Just short AF73 to earth when the key is on. If the pump runs, then the relay is fine, and all the power up to both inputs on the relay is fine. If it doesn't run (and given that you checked the relay itself actually works) then one or both of AF70 and AF71 are not bringing power to the game.
    • @PranK can you elaborate further on the Colorlock Dye? The website has a lot of options. I'm sure you've done all the research. I have old genuine leather seats that I have bought various refurbing creams and such, but never a dye. Any info on how long it lasts? Does it wash out? Is it a hassle? What product do I actually need? Am I just buying this kit and following the steps the page advises or something else? https://www.colourlockaustralia.com.au/colourlock-leather-repair-kit-dye.html
    • These going to fit over the big brakes? I'd be reeeeeeeeaaaall hesitant to believe so.
    • The leather work properly stunned me. Again, I am thankful that the leather was in such good condition. I'm not sure what the indent is at the top of the passenger seat. Like somebody was sitting in it with a golf ball between their shoulders. The wheels are more grey than silver now and missing a lot of gloss.  Here's one with nice silver wheels.
    • It's amazing how well the works on the leather seats. Looks mint. Looking forward to see how you go with the wheels. They do suit the car! Gutter rash is easy to fix, but I'm curious about getting the colour done.
×
×
  • Create New...