Thread: hunting idle fix with nismotronic.

thought i'd post this up. it appears there's more than one sr20ve owner out there with idle issues. this is my story. its not completely finished, however its worth looking at for those of us who do happen to have Nismotronic as their preferred engine management, and as changes are so easy to make and revert back if they dont work.

when i first put my ve in, the idle was very high. the cause i now know was too high a iacv percentage. what i did to band aid it (q45 throttle body), was to screw out the throttle body stopper until it went down. out of that i got 2 problems. hanging high idle return (iacv%) and high idle (stuck throttle body).

what i also inherited from my ve swap (sometimes, not all the time) what i'd call a hunting idle. had it first turn of the key. here's a video of it in action.

http://vid1334.photobucket.com/albums/w660/sss4me/IMG_0380_zpswxu7x0rg.mp4


it has been suggested that this may occur from the engine's mating change from a cvt transmission to (in a lot of cases) a lightweight flywheel. certainly happens on ve's with other engine management as well. i thought my bigger plenum may play a part too (unproven atm).

here's what i done to combat these issues.

* reduced to iacv percentage ( my tuner alerted me to this at my dyno tune , but couldn't get to it ). from 40 ish % down to 25%. pro tip is to use nismotronic to lock the timing, then adjust the iacv screw a bit, unlock the timing, and see what the new percentage is. pretty easy to do this with the iacv in its stock position. motor must be hot.

* adjusted the q45 throttle body stopper back out to a stock position.

* reduced the idle recovery duty. this is what's stock



and this is where mine has ended up



* changed the TPS Open low timer to 500msec
* changed the TPS Open high timer to 250msec

this solved the hunting idle (all except first cold start in the morning, it lopes few a few seconds until it settles at 1500rpm cold idle).

these changes also created a new problem. sometimes the return idle would decel nicely down to 1100rpm, before settling at 900, other times it would completely die without warning.

i fixed this by..

* Set low error update rate to 250msec ( this wasn't enough ). eventually i went down to 150msec. this new setting appears to have fixed the stalling issue. the return idle sits at 1100rpm a bit longer now than before, before settling at 900, but i will gladly accept that.

my thanks to john kerr and darryl stokes for his help. champions!.

Thanks for sharing!

Just to clear a few things up,

You had this problem with both stock and q45 80mm throttle body?

Also both throttle bodies have that factory coolant cold idle device. Which can cause a high idle after a swap. This should be disabled.

Also are you using the air regulator in combination with the IACV?


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i had a q45 throttle body from day1, and have looped the "factory coolant cold idle". also removed the waxstat and spring. unaware of any air regulator.

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VEs don't have air regulators

Yes, this happens with the stock intake manifold and throttle body

Thanks for sharing, I know squat about tuning and have always had this issue on my VE.

I found that getting the lower cells in the fuel table around idle is very important. I was able to solve quite a few idle issues with "balancing" those cells. It is hard to say what exactly is correct, but if the cells were changed too much the idle would be erratic. I will look into your suggestions when I get my car driving again, but I want to say I already changed these tables anyway. If I did I will post them tonight or tomorrow.

OP's tips are a great way to start adjusting your 20VE idle.

The one that did it for me, was capping the max idle % to 40, instead of the stock 95%. Adjusting the timers smoothed it out abit aswell, thanks for sharing your settings!

did you set the Closed Loop Timing at 5deg under 1600rpm?