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High Idle after Tps adjustment R34

~KnuckleDuster~

By ~KnuckleDuster~,
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~KnuckleDuster~ Rookie

~KnuckleDuster~

Posted
Posted (edited)

The motor is an Rb25de from an R34. I noticed my tps voltage was .20 closed. I adjusted it to oem specs at 4.5 or so and that's when I started getting the high adle around 1300-1500. If I unplug the aac the idle goes back to normal. If I set any values on the aac in consult the idle goes back to normal. I thought I may have a bad tps and installed a new unit but the same thing. The aac adjustment screw is all the way down (and broken so I cant back it out again). I've cleaned it out a while back but never had an issue until now. Not sure why my idle is screwed now because I touched the tps..

Edited by ~KnuckleDuster~
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~KnuckleDuster~ Rookie

~KnuckleDuster~

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Anyone? If I'm a dummy feel free to let me know. Iv'e attempted to set the base idle per the write ups, I lowered the tps closed voltage back to where it was at .2 and still high. Cleared the ecu memory. Not sure if there's another song and dance I need to perform to have the new tps setting dialed in or if the next step would be to open up the aac and inspect that.

Kinkstaah Grand Master

Kinkstaah

Posted
Posted

The R34 also has a manual throttle stop bolt, I always found that adjusting that was easier than the screw in the side of the AAC itself which appears to be made out of something with the strength of warm butter.

I had many R34 AAC's fail in general to the point where I bypassed it with a BMW unit lol

~KnuckleDuster~ Rookie

~KnuckleDuster~

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The timing was around 17* last I checked when the idle was low enough. The throttle stop bolt is backed out all the way.

The black plastic adjustment screw which was broken off was at least tightened all the way down which is the lowest point for the idle to be at but the idle was still at 1300. I chipped out the broken screw and put in a medal adjustment screw from an rb26. Now the idle is at 2k. If I unplug the aac the idle is still high around 1100-1200. I just don't get why adjusting the tps from .2 to .4 has f'ed this whole thing up!

Worst part is I'm in the US and finding an AAC from a DE is insanely difficult.

 

 

Edited by ~KnuckleDuster~
Kinkstaah Grand Master

Kinkstaah

Posted
Posted

How sure are you that you don't have a leak? What happens if you block off the hose going to the IACV?


In the end I hollowed out my R34 IACV entirely, and just ran another IACV in the hose that runs to it. Only going to really work if you have an aftermarket ECU that is controlling said IACV though.

Note: My 34 one failed and when it fails, it fails open. As above, no leaks, throttle stop bolt entirely out, idle of 2000RPM.

Why not just change TPS voltage when closed back to 0.2? I noticed in my car (again not completely the same) that voltage when car on but not running may have been 0.2, but I would find that 0% throttle with car running the voltage was different, perhaps 0.5 actually.
 

~KnuckleDuster~ Rookie

~KnuckleDuster~

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Pretty sure I don't have a leak, I have a full time vac gauge in the car. Ill see what happens when I block the hose off and run it today.

If I could get away with just bypassing this thing I will. I'll do that as a last resort. I put the tps back to 0.2 and the idle was still 1500. Used to idle around 750-850 prior to me touching the tps.

I'm using the consult port and running datascan software so I can select values on the aac. If I put it anywhere from 1-9 the idle drops down. So it's as if the aac is just staying wide open unless manually told to do something different.

Edited by ~KnuckleDuster~
~KnuckleDuster~ Rookie

~KnuckleDuster~

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Ok so blocked off the vac to the aac and started it up. Still revs to 2k but will hunt from 1300 to 2k. With the vac blocked and aac unplugged the car starts up fine and the idle is wavering around 1000, revs and sounds healthy.

Is that a sufficient enough way to bypass this thing? Is it ok to leave the coolant running through it?

Edited by ~KnuckleDuster~
GTSBoy Grand Master

GTSBoy

Posted
Posted

The coolant should be left going through it as it is the high point bleeder on the whole circuit.

"Bypassing" is by just blocking off its air supply is a bit crude.  You own't have idle up for air-con or high electrical load.  But if it's already idling high, that's probably not going to stall you out.

I would try another ECU.

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