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Discussion Starter · #1 · (Edited)
UPDATED JUNE 14, 2011
Okay so I took some time last night to figure out the problem again.

Turns out the IAC valve was still messed. I discovered this by covering the small hole inside the TB. As soon as I did this, the idle went down and stabalized.

I took the TB, IAC valve and IAC sensor off completely again to inspect the parts. Everything was still clean, but I suspect the IAC sensor that goes over the magnetic handle that controls the valve wasn't on properly.

Initially I couldn't tell if there was a groove or pattern that made sure you installed the IAC sensor properly. So I guess I didn't install it correctly.

Anyway, after double checking everything, the car runs fine now. Idle seems to be stable, although the true test would be me driving in stop + go traffic for an hour in hot humid weather.

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UPDATED JUNE 13, 2011

Okay guys.. i was able to take apart the IAC Vavle completely and the sensor that's attached to it. I cleaned it up real good. used a tiny bristle brush on my rotory tool to really get off that carbon build up. sprayed some more brake cleaner and then sprayed some penetrant lube to make sure the valve would spin, and on the TB area.

My IDLE is EVEN MORE FUCKED than before.
These are the new videos of what's going on.
http://www.youtube.com/watch?v=8U3uCCLUBWE

There's also this effing weird sound coming from the TB. Like a vacuuming sound or a high hiss. When I put my hand over the TB, the car dies.
http://www.youtube.com/watch?v=fffgybOIfnI

I already checked for vacuum leaks on all the hoses going into manifold and TB.

WTF is going on?!?!

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BELOW IS MY CAR BEFORE JUNE 12, 2011.

Here's a quick video to show you what I'm seeing.
This was recorded after driving to work, 15 minute commute, city driving.
http://www.youtube.com/watch?v=odwT0gkykeU

This was recorded after driving to a friends place nearby. Slightly stop and go traffic, about 5 mins of driving, in very humid weather.
http://www.youtube.com/watch?v=dyOzwWV1-tQ

During stop and go traffic or driving long periods of 30 mins or more, or during hot weather, the needle will go up and down between 1K - 2K.

I tried cleaning the IAC valve. I took the TB off, but couldn't take the IAC off because one of the screws is seized and the screw head started to get stripped. I tried anti seize and tapping the screwbit into the head, but that screw is stuck for good.

so I used carb cleaner to fill the holes and soaked it around. Shook it, wiped it and did this multiple times.

Other notes:
When I'm driving, if I decide to shift to Neutral and coast, the RPM does not drop immediately. It slowly drops to 1000-1500.

When I am coming to a complete stop and I shift to Neutral, the RPMs shoot up to 2K and than drops down to 800-1000. Sometimes it just shoots up to 2K and than drops to 1000-1500.


I know i have to do a vacuum leak test still, but thought I'd post up what I had for now just in case.
 

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The Almighty
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25,301 Posts
u have to remove the iac to completely clean it. cut a flat slot in the screw head and use a flat head screwdriver to it and it should come out. the carbon build up has to be scraped off the iacv to clean it completely
 

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my d17 does both of those a lot. does that mean i need to clean my iacv? to fix it i just turned up the idle valve duty cycle in kmanager so its like 80% along that slider.
 

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Discussion Starter · #6 ·
Okay guys.. i was able to take apart the IAC Vavle completely and the sensor that's attached to it. I cleaned it up real good. used a tiny bristle brush on my rotory tool to really get off that carbon build up. sprayed some more brake cleaner and then sprayed some penetrant lube to make sure the valve would spin, and on the TB area.

My IDLE is EVEN MORE FUCKED than before.
These are the new videos of what's going on.
http://www.youtube.com/watch?v=8U3uCCLUBWE

There's also this effing weird sound coming from the TB. Like a vacuuming sound or a high hiss. When I put my hand over the TB, the car dies.
http://www.youtube.com/watch?v=fffgybOIfnI

I already checked for vacuum leaks on all the hoses going into manifold and TB.

WTF is going on?!?!
 

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Discussion Starter · #8 ·
I've done ECU reset before, when working on car for other issues, the idle has never acted like like what i see now.

I just went out to the car to try a ECU reset, but the idle is still acting krazy.

I'm wondering if there's a leak between the Throttle body and Intake Manifold. Maybe the Gasket is fucked.
 

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The Almighty
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im betting on theree being a vacuum leak for sure. the iacv is trying to compensate for the vaccum leak and hence the screwy idle. my suggestion is get some carb cleaner and spray around areas where u hear the vacuum leak, when the idle dies or bogs way low u r getting close. if u are using an afr gauge u should see way rich when u hit the correct spot
 

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Discussion Starter · #10 ·
Okay so I took some time last night to figure out the problem again.

Turns out the IAC valve was still messed. I discovered this by covering the small hole inside the TB. As soon as I did this, the idle went down and stabalized.
I took the TB, IAC valve and IAC sensor off completely again to inspect the parts. Everything was still clean, but I suspect the IAC sensor that goes over the magnetic handle that controls the valve wasn't on properly.
Initially I couldn't tell if there was a groove or pattern that made sure you installed the IAC sensor properly. So I guess I didn't install it correctly.

Anyway, after double checking everything, the car runs fine now. Idle seems to be stable, although the true test would be me driving in stop + go traffic for an hour in hot humid weather.

I'll probably need to replace the TB gasket now though as the current one isn't doing so well. A small pace near the bottom is about to fall off.

The headaches never stop.

Thanks for all the help Greenie.
 

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If you plugged the hole that goes to the IACV in the throttle body and the idle goes down then its not a sign of a vacuum leak. If you feel you need to be reassured then go ahead and spray some soapy water where you feel it could be and watch for bubbles.
Once you off your IACV and clean it you would want to make sure it is COMPLETELY dry before you reinstall it. Also because youve disconnected hoses in the coolant you might want to try bleeding the coolant. Air bubbles in the coolant can cause fluctuating idle.
Does the idle take a while to go down after you accelerate? Have you messed with the idle screw? Also you DO NOT want to mess with that magnetic screw on the IACV. Most likely if youve unscrewed that cover and exposed and retracted the magnetic thing in there then it will be messed up.
 
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