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Thread: Anyone else had ongoing issues with hunting idle?

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Posts: 11-20 of 20
2013-07-16 14:38:15
#11
I've gotten rid of this a few times on 3 different SE-Rs.

  • Set timing with timing mode and light
  • Reset ECU
  • Make sure high idle assembly on VE throttle body is in spec

On the first one I think the timing slipped a little over time. The second one I think the car got confused because I was doing a lot of little changes on a new setup. The third one I believe because the weather changed a lot warmer and I hadn't driven it for several months the tb adjuster was off.

Hope one of those can help.
2013-07-16 14:59:15
#12
Also, double check that you don't have a cyclical o2 trim, meaning that it isn't bouncing between (+/-) 10% O2 trim.

This can cause a sway in map load and can cause a hunting idle.
2013-07-16 21:51:15
#13
Yeah I have this issue when the car is cold, but it settles after maybe 2-3 minutes of driving. Also random jerky very little throttle, as if the car can't decide between saying the throttle is or is not open. Haven't really looked into it but figured I'd share.
2013-07-16 22:50:51
#14
my car will do this if i hop it in real quick an go for a super short drive (like to a store) then when i start it, it'll go to 1500 or twice kinda slowly, if i let it do it it's fine an will be ok the rest of the time, if i just take off it'll freakin keep doing it until i let it just do it lol.
2013-07-17 03:30:22
#15
I've been having an an issue with high idle ever since I went OBD1, goes back to even Calum RT that I had. Every few days/weeks the car will start and will idle at 2500 rpm and not return to 800rpm no matter what. One thing I noticed is, TPS closed flag is off when this happens. If I turn off the car, wait 3 seconds for relay to reset, start the car, TPS will show up as Closed and will idle perfectly at 800rpm.

My best guess on why I'm seeing this is because OBD1 TPS doesn't have enough power for anything else but the TPS. OBD2+ started using TPS power for a lot of other things, if you plug up more then one additional item to the TPS feed, the TPS will never get to 5.05V fully open either. My best guess on fixing this issue is remove everything from using TPS 5v feed.

Does this sound similar to the issue your having?
2013-07-17 13:53:49
#16
Idle speed is not controlled unless the TPS closed flag is ON.

I am currently powering my MAP sensor with the TPS 5V power with no problems, however it is recommended to use the 5V power from the break-out box to power other sensors.
2013-07-17 17:41:08
#17
Not sure if this helps, but try closing the idle adjuster on the IACV, i had a bouncing idle/recovery before, since i did that i have had no issues.
2013-07-29 06:40:09
#18
Changed my alternator last night, was having issues with low voltage after driving for a while, which seemed to have some relationship to the idle hunting. Drove around for a while today, lots of short drives, was absolutely fine until i went to dyno shop to book a dyno day, told the owner how awesome the new computer was, started the car and it sat there idling from 600 to 2000rpm for about 20 seconds before settling. Felt awesome.

Ive checked all my earths, ive tried opening and closing the IACV bleed, ive tried raising and lowering the base duty cycle/water temp table.

I recorded logs a couple of times, but was almost convinced i had fixed the issue, and so typically i didnt have laptop connected and recording when it did it. The problem usually happens when the wideband is still warming up, so no way of telling if the afr is the issue, or afr is swinging as a result of whatever is trying to control the idle.
2013-08-16 19:44:09
#19
I know think the alternator was causing most of the issue. The car is definitely a lot better, can be driven slowly in low gears easier.

I still feel I have a table in the idle table that's over compensating when idle I out, but since the rpm is not dropping dye to voltage drop it's not getting itself into this situation as much.
2013-08-16 19:58:55
#20
Originally Posted by Vadim
I've been having an an issue with high idle ever since I went OBD1, goes back to even Calum RT that I had. Every few days/weeks the car will start and will idle at 2500 rpm and not return to 800rpm no matter what. One thing I noticed is, TPS closed flag is off when this happens. If I turn off the car, wait 3 seconds for relay to reset, start the car, TPS will show up as Closed and will idle perfectly at 800rpm.

My best guess on why I'm seeing this is because OBD1 TPS doesn't have enough power for anything else but the TPS. OBD2+ started using TPS power for a lot of other things, if you plug up more then one additional item to the TPS feed, the TPS will never get to 5.05V fully open either. My best guess on fixing this issue is remove everything from using TPS 5v feed.

Does this sound similar to the issue your having?



I had the same issue as well (the TPS closed flag was finicky at best) and it only manifested itself recently (went through a few track days with nary an issue). It looks as if my throttle cable is somewhat stretched giving it incorrect readings (the TPS sensor is fully rotated CCW to compensate, which most definitely isn't correct and will also offset the higher values). However, changes can be made in the software to compensate, but that is a different matter and still does not tackle the "mechanical" issue at hand (no band aid fixes here)

I ended up tacking this by remounting the TPS, re-wiring my throttle cable (until the brand new one arrives), and also adjusting my WOT voltage to read 100% when the throttle is wide open. In addition, I had to fiddle with the idle screw in order for the car to "catch" itself once the revs are dropping rapidly (eg: like clutch in/neutral engagement while high up in the RPM, kinda like a dyno run)

The main issue I am getting at here is there are several reasons why the idle could be off with a few of them being

1) Main one I see for myself - The TPSclosed flagged is not initializing (this HIGHLY affects idle paramters as well as intiating idle conditions and maps in the ECU)
2) The TPS data stream is incorrect
3) The idle screw on the IACV is not adjusted correctly

As @JKTUNING has said, typically when there is an issue going on, the software is so well written it ends up being a mechanical issue and NOT an issue with the software. However, the software is a great tool at diagnosing and tracking down what the issue is if you know how to use it and just use a little thought in figuring things out.

P.S Yes I am late to the party and read your post Evlnxr
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