Cant figure out my stupid Idle.

**Dylan19** · 09-05-2011, 04:27 PM

Hello all!
So my car is idling at roughly 14-1500 rpms and this did not bug me, until air care told me I gotta lower it -.-. So i tried the AAC valve adjustment screw and of course it wouldnt be that easy. It did absolutley nothing, I closed the screw right up and nothing. So i took The AAC valve off and cleaned it out with some carb cleaner, screwed in brass piece to tighten up the spring a bit made sure it was all clean and bolted her back on. (What a convienent place nissan placed this in -.- I must say

.) I kept the brown plug unplugged and started her back up, The idle is the same, So i tried screwing the adjustment screw back in and it again, doesnt do anything. Plugged the brown plug (TPS) Back in and the idle does not move. Also, when I turn on the a/c the idle does not change or move. I read somewhere this means my aac valve assembly is hooped. Any advice? Also does anybody know if the 300zxtt shares the same assembly? I have a close buddy who has one coming in and does not need it anymore, judging from pictures it looks the same.

**v8-killer** · 09-05-2011, 08:18 PM

when i used to have a 300zxtt it did the same thing and it was my TPS. even now on my GTR , the idle is at 1400rpm but i got bigger injector so i need to adjust my fueling. are the injectors on ur car stock? do u have after market ECU?
cuz i got 880cc's and i havent figured out whats the fuel % should be on power fc and whats dead time so thats why its idling high.

**Smilez** · 09-05-2011, 11:18 PM

v8-killer: http://www.paulr33.com/powerfc-faq/powerfc-faq.htm#57

you're going to need to find out the latency of your injectors. check the manufacturer's website for product info, most have the latency listed.

**v8-killer** · 09-05-2011, 11:55 PM

yeah i check that already. i fount the INJECTOR correction already the only thing i have to play around is the latency. but before anything else i need to change my fuel pump

thanx tho

**93_jdm_fd** · 09-06-2011, 10:05 AM

I just went through the same thing on my gtr. The idle was at a perfect 1500prm. The idle screw was already turned at the way in. I found a post saying if the throttle bodies have ever been off and cleaned it will cause a steady high idle. I just got the engine back together on my car and found the idle high.

So I removed the throttle linkage while the car was running to see if maybe the linkage was not adjusted properly. I found no change in idle. So next was to reset all the throttle stop screws on the throttle bodies for the throttle plates. You can do this without removing the intake manifold. I found my front pair of throttle bodies had the screw turned in farther than the rest. I loosened off the 8mm lock nut and turn the screw back so the throttle plate could fully close.

Started the car right up and now the idle was at around 750rpm!! Now I turn the idle screw out a few turns and now the idle is perfect at 950rpm,

All the throttle plates have to be air tight, no light coming through when pointed towards light. Just look down at the throttle plate stop screws and see if they are even. Like I said I had one turned in quite a bit from the other two.

**Dylan19** · 09-06-2011, 02:11 PM

Thanks 93jdmfd! I will head outside and try this right now.

**Dylan19** · 09-06-2011, 03:04 PM

Alright, just from going out to take a closer look at the throttle body and intake manifold are I found something that just doesn't seem right to me. But who knows, I have been wrong before. I circled them in red. It appears there is 3 very small holes that I dont think, Are supposed to be there. Just shouts out leak to me. Can easily fit a pin or something into them. Its like the gasket is supposed to be a cm or something ? Sorry for the camera phone pics :P

**604_R32** · 09-06-2011, 03:34 PM

Now thats just weird...

**bobbo** · 09-07-2011, 07:40 AM

The holes are nothing. Something from the casting I'd guess. I'm guessing from your discription of how you tried to adjust your idle you don't have a service manual. There is potentiometer on the side of the ecu that you need to turn aswell for idle adjustment. I'm away and don't have my manual with me so I can't give more details on that.
Another common problem with high idle on RB26s is the throttle linkages being out of adjustment. Undo your throttle cable and verify that you don't have any throttle plates being held open.
Yet another problem causing high idle is, of course, vacuum leaks and the finally the recirc valves often don't like to seat so they will allow air to pass back to the far side of the mafs and "APPARENTLY" this can/will cause a high idle.
I've been chasing the same problem for awhile now and have gone through all of the above save checking the recirc valves. That will be on this winters "to do" list.
Good luck!

**93_jdm_fd** · 09-07-2011, 08:01 AM

I had the same problem, removed the throttle cable and nothing changed. I removed the throttle linkage from the manifold just to make sure that none of the linkage arms were hold the throttle plates open and still the idle didn't drop. Next was to reset the throttle plate stop screws. As soon as I loosened off the lock nut and backed out the first stop screw the idle dropped right down to like 750.

I had all the linkage arms off the main throttle so that I could back all the throttle plate stop screws out until I could feel the throttle plate bind in the bore, then I turned the stop screw in about a 1/4. Once I could feel the throttle plate not binding in each bore but pulling on the rod I tightened down the lock nut while hold the stop screw from turning in. Fired it up and the idle was really low, then just back out the AAC valve from fully closed to bring the idle to 950. If you guys have checked everything then this is probably your high idle problem.