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Old 08-02-2019, 03:09 PM   #1
White-o
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Default Idle issue (yes I read all the other stickies and threads)

Been having this issue for over a year and no one can figure it out. I've got a JDM 205 in my Bugeye and it has an inconsistent idle. Somedays it will idle rock solid. Other days it will act up. When it acts up it will bog down before returning to a normal idle. When idling say in a drivethrough, sometimes it will sit at normal idle but rev up a few hundred or maybe even just a hundred rpm every second, continually. Sometimes after getting off the throttle the rpms will stick at 1,000 for awhile. Sometimes getting off the throttle the rpms will bog out to 500 or so and then return to normal. The car has never stalled out on me. And as I said, some days I can let it idle for extended periods of time with nothing going wrong whatsoever.

I just had a new throttle cable put on because my old one was sticking, but it did nothing. I've cleaned my iac and put in a new gasket to solve a consistent high idle, and that's when this all started.

I have not adjusted my cruise control cable, but everyone with that issue seems to have constant high idle. I'll try to get out and check the cable the next time it does it if possible.

I've not found any vacuum leaks.
I've cleaned my maf sensor but when I took it out it already looked brand new.

As I said the trouble only seems to appear after heat has been able to really flood the engine bay, like if I drive 10 minutes and then stop and continue to idle for another 5 or 10 minutes.

Any suggestions you've got I'll take them.
I can't see what botching an iacv cleaning could do to cause this but perhaps I just need a new one? The valve isn't supposed to do anything after operating temperature as I understand it, so I don't see what it could really be doing.
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Old 08-02-2019, 06:26 PM   #2
subaru_gc8
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who tuned it? to me it sounds like a hot idle issue
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Old 08-02-2019, 07:55 PM   #3
Crispy 1
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Location: Hendersonville, NC
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Iacv!

I cleaned mine when I first got my bugeye and it worked perfectly for about a year. I was working on something else with the intercooler off and noticed it looked dirty so I cleaned it again and it went crazy.

I ended up taking it apart further and meticulously cleaning it. It still sometimes acts funny but barely ever. I think I just need to eventually get a new one and plan on it if I still have the problem once my built ej207 goes in.

If you take it apart make sure to mark exactly where it sits in the slotted bolt holes.

Oh and your iacv is working anytime its idling as far as I know. If not you would have to hold the throttle open slightly to make it idle at all since the blade is closed completely.
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Old 08-03-2019, 03:14 AM   #4
mik_sti
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Try removing the iacv motor itself and rotate the swing valve a bit to free it up, iirc the motor is magnetically controlled and doesn’t make contact with the part on the throttle body, if it gets stuck especially if the vehicle has been sitting for a while it would cause strange idling issue, a few movements to clear it up should do the trick. Also check your front o2 sensor, it could be failing or the wiring could be deteriorating with age. You could probabaly cross reference your af correction 1 with your front o2 afr against your wideband afr, could probabaly barrow down if it’s the o2 sensor
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Old 08-05-2019, 12:53 AM   #5
mammeor
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Quote:
Originally Posted by mik_sti View Post
Try removing the iacv motor itself and rotate the swing valve a bit to free it up, iirc the motor is magnetically controlled and doesnít make contact with the part on the throttle body, if it gets stuck especially if the vehicle has been sitting for a while it would cause strange idling issue, a few movements to clear it up should do the trick. Also check your front o2 sensor, it could be failing or the wiring could be deteriorating with age. You could probabaly cross reference your af correction 1 with your front o2 afr against your wideband afr, could probabaly barrow down if itís the o2 sensor
My idle was also very screwy which substantially improved with the following (now it's 98% of the time good...mind you it's an 03):
- cleaned IACV & replaced small rubber gasket (does magic)
- turbo inlet leak @ turbo (PITA to replace)
- small vacuum leaks here and there (new gaskets & small vacuum lines whenever I find a new one...)

Hope this helps
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Old 10-21-2019, 11:55 AM   #6
White-o
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Thanks for all the replies! I'm thinking of just buying a new iac so that I can eliminate that from the equation if it continues to act up afterwards. It stalls on hot starts now if I don't give it a blip but otherwise its the same. Sometimes it idles really low when I'm in gear and have the clutch depressed. Strange. Anyway, thanks for the suggestions everyone!
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Old 10-21-2019, 01:54 PM   #7
snow_bound26
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Had the same issue almost word for word with JDM. It was the IACV. Take it off, soak it gas overnight and then clean it with cue tips again. There’s a spring actuated piece that looks like a cylinder on one side and open on the other. You have to rotate it so you can clean the side not visible under it. I held it open with a tooth pick so I had room to move the cue tip around. Idle was fine after that.
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Old 10-21-2019, 04:19 PM   #8
Fozymandias
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I chased this issue for quite a while - my stalling and intermittent low idle was caused by my front O2 sensor going out of spec. Easy way to test is simply unplug it and go for a drive.

The other issue I had which threw an IACV fault was the neutral switch on my gearbox. Plug in a diagnostic and check that it is registering when itís in gear and in neutral.
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Old 10-22-2019, 10:53 AM   #9
White-o
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Quote:
Originally Posted by snow_bound26 View Post
Had the same issue almost word for word with JDM. It was the IACV. Take it off, soak it gas overnight and then clean it with cue tips again. Thereís a spring actuated piece that looks like a cylinder on one side and open on the other. You have to rotate it so you can clean the side not visible under it. I held it open with a tooth pick so I had room to move the cue tip around. Idle was fine after that.
Alright I'll have to do something with that then. I know I wasn't extremely thorough the first time
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Old 10-22-2019, 10:57 AM   #10
White-o
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Quote:
Originally Posted by Fozymandias View Post
I chased this issue for quite a while - my stalling and intermittent low idle was caused by my front O2 sensor going out of spec. Easy way to test is simply unplug it and go for a drive.

The other issue I had which threw an IACV fault was the neutral switch on my gearbox. Plug in a diagnostic and check that it is registering when itís in gear and in neutral.
I just had my o2 sensor replaced a couple months ago because it had completely died. Some of the idle issues remained after the new one but it may have eliminated a few of them? Idk lol. I'll check into that neutral switch thing too. Is that the switch thats in between the seats somewhere? Or the switch on the clutch pedal? The one on my clutch pedal is broken and I don't have cruise control. But I'm pretty sure thats not the switch you're referring to lol.
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Old 10-22-2019, 10:59 AM   #11
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Quote:
Originally Posted by subaru_gc8 View Post
who tuned it? to me it sounds like a hot idle issue
Mikey Botti
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Old 10-22-2019, 01:26 PM   #12
Fozymandias
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Quote:
Originally Posted by White-o View Post
I just had my o2 sensor replaced a couple months ago because it had completely died. Some of the idle issues remained after the new one but it may have eliminated a few of them? Idk lol. I'll check into that neutral switch thing too. Is that the switch thats in between the seats somewhere? Or the switch on the clutch pedal? The one on my clutch pedal is broken and I don't have cruise control. But I'm pretty sure thats not the switch you're referring to lol.
Itís on the gearbox - towards the back on the LHS - one at the front is the reverse switch, one at the rear is the neutral sensor - should have two wires coming from it. But easiest just to check on a diagnostic - it will change between Ďin neutralí and Ďother than in neutralí as you move it from neutral to gear and back.

Re the O2 sensor - if it wasnít an OEM one I wouldnít rule out the new one going bad too - notoriously sensitive cars! I went through both a Denso and a Bosch Universal before stumping up for an oem one which finally worked. Denso didnít work at all, Bosch lasted a week or two. Just unplug it and take it for a drive - costs nothing, takes 2 minutes and if nothing else will narrow down the issue
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Old 10-23-2019, 03:58 PM   #13
White-o
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Quote:
Originally Posted by Fozymandias View Post
Itís on the gearbox - towards the back on the LHS - one at the front is the reverse switch, one at the rear is the neutral sensor - should have two wires coming from it. But easiest just to check on a diagnostic - it will change between Ďin neutralí and Ďother than in neutralí as you move it from neutral to gear and back.

Re the O2 sensor - if it wasnít an OEM one I wouldnít rule out the new one going bad too - notoriously sensitive cars! I went through both a Denso and a Bosch Universal before stumping up for an oem one which finally worked. Denso didnít work at all, Bosch lasted a week or two. Just unplug it and take it for a drive - costs nothing, takes 2 minutes and if nothing else will narrow down the issue
Okay I'll take a look! I don't have a diagnostic tool to check that with though so I'll have to just try to find it. And mines an oem sensor.
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