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Runaway Idle

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Hey guys,


Having an issue. When idling or creeping for extended periods, my idle creeps up to 1500-2000RPM or more. 

Not an issue around town, or in normal day to day driving.  Today on the way into an amusement park - we sat in traffic for a good 45 minutes to get into the park. 

Towards the end was trying to idle around 3000RPM in neutral and due to having to creep so much(in drive) I ended up overheating and causing a CEL w/a engine overheat code (250F ECT). Basically doing a brake stand for 45 minutes....

I'm guessing either a vacumn leak or a bad IACV....any ideas? 


2001 VQ35DE 4AT 196k miles. 

Edited by Inyourface1650
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had the same thing happen on my 96, i think it was after i cleaned my throttle body.


Throttle position sensor was out of wack, needed to be rewacked. FSM has the procedure on how to do that.


Cant say for sure its whats wrong since you have a 3.5 but its where i would start. 



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Ran around town yesterday, and this morning and was absolutely fine. 4-5 separate short trips and not a single idle issue. I can do the idle re-learn but being that its only done this after EXTENDED idling with the AC going, I'm not convinced that's it.

Almost seems like thermal expansion opening up...something.

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A friend of mine has a 99 Pathfinder that did that and his was a vacuum line had come off of something up under the back of the intake. Replaced the line and it hasn't done it since. At least that I've heard about.


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  • 1 month later...

So - I figured this out.


When i got the Truck about 10 months ago it had a very loose throttle cable, so I tightened it.  Apparently a bit too much.

The other (quite hot) day it started to race again- I popped the hood and pressed hard on the throttle (body) and it instantly dropped to "normal idle". So my throttle was opening, Loosened the cable a touch and here we are. No more runaway throttle.

No problem through winter, no problem in daily driving, but when it the truck got hot as described above, the throttle cable sheath must expand just enough to crack the throttle.


*feeling rather stupid*

Edited by Inyourface1650
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