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Discussion Starter #1
On most cars the IAC is integrated into the throttle body. However I don't see the any small vent hole that usually resides before or right along the throttle plate.

I assume this is because the TB is drive-by-wire, and therefore the electronics controls the throttle plate and sets the throttle plate to allow for idle air to pass through.

Is that the case or am I not looking close enough?

Here's a snapshot:
 

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Discussion Starter #3
Great. Anyway the reason why i asked because it kind of confirms some ideas I've been pondering about lately related to some stalling instances I mentioned a few times on here. I believe such a design makes the car be more susceptible to idling issues because of gum-up along the inner lip which the throttle plate butts up against. As you can see the throttle plate is not fully perpendicular to the air flow because the air passage narrows through the TB. Some folks have bored out the tapered ring around the throttle valve not understanding the design was to accelerate the air going through it (venturi effect). Anyway in my case this ring doesn't taper both ways, it simply drops off leaving a lip along the bottom which the throttle plate butts up against when it swings down. I learned this when I reached in to clean the area around the plate and felt that little 'step'. I surmise it was designed this way to produce some turbulence in the airflow as it pass through which may be beneficial also (just a theory). But as a consequence gunk can build up along that lip and essentially block what little air that was allowed by the very narrow gap allotted for idling. With an independent, isolated air channel for IAC, there is far less restriction as the opening is a hole and not a long thin gap along the throttle plate. (I hope I'm describing this theory in a way that makes sense.)

Like I said, as some of you know, had a few instances with stalling out at slow speeds when giving just a little gas at a time and getting out of gear into neutral (such as moving the car up a position in a turn lane or in traffic jams). I observed that when the RPM's drop to idle, the engine slows down too much, the tach shows the needle dipping below the normal idling range, like around 300RPMs then going back up to 500RPM. But on occasion, it dips even lower and the engine stalls. This has never happened with day to day normal driving, where usually I accelerate to higher speeds. When traveling at speeds higher than, say, 10mph, then going into neutral, the engine will idle at around 1000RPM and stays there for a while until the car slows then it gradually lowers to 500RPM as the car slows to a stop.

Anyway ever since cleaning the TB, I have not seen the same behavior. The RPMs now no long drop below 500 RPM and in fact climb a bit before settling at 500RPM. I believed I have effectively resolved an issue that has been bugging me for quite some time. Man it feels good to fix your own car simply by taking care of it! :D

If any of you ever have similar issues mind your TB- it might be gummed up like mine was. Keep in kind it didn't take much gunk, in fact what you see in the picture above was what my TB looked like before cleaning (no lie). The only gunk I wiped away was along that little step I was talking about, behind the tapered ring. It literally took a couple of minutes to wipe away, no solvent needed.
 

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Typically the only piec within the throttle assembly that has any probability of making trouble is the air quantity sensor. These have been known to deteriorate or have problems with dirt.

So, if you have a serious issue let your dealer check that, though your effort may already have sufficed to clean it.
 

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Discussion Starter #5
Typically the only piec within the throttle assembly that has any probability of making trouble is the air quantity sensor. These have been known to deteriorate or have problems with dirt.

So, if you have a serious issue let your dealer check that, though your effort may already have sufficed to clean it.
air quantity sensor = mass air flow sensor?

I've already inspected that a couple months back and there was no noticeable dirt. Nevertheless I went ahead and washed it out with CRC Mass Air Flow Sensor cleaner. While it didn't resolve the stalling tendency, I believe it did help the air temp sensor issue I had also, because in the process of cleaning it, I cleaned the air temp sensor as well, since it is integrated into the unit.
 

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I find it good habit to clean your TB and MAF relatively regularly, even with Catch Cans. On that note-squid do you have catch cans? that will solve probably 95% of the gunk problem or at least mitigate it to the point where the buildup will take much much longer.


On my wife's cobalt for example-she gets tons of much blow by coming from the CCV system even with catch cans, I typically clean it every two oil changes (the TB) and while I'm at it clean the MAF as well. Hers is DBW and has that same lip, not to mention the 2.2 ecotec is notorious for blow by. In her car it got so bad that the valve was catching on the open and the close and stalling on deacceleration, and other times would cause hang ups when revs were falling or horrible idling.

I haven't pulled my Evora one yet and need to do so, hopefully in conjunction with a catch can installation soon. IIRC the 2GR-FE also has some history of putting a decent amount of blowby through the CCV system.

TBs are relatively easy to clean so it is definitely worth regular attention-and probably the solution to a lot of peoples issues.
 

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Discussion Starter #7
I find it good habit to clean your TB and MAF relatively regularly, even with Catch Cans. On that note-squid do you have catch cans? that will solve probably 95% of the gunk problem or at least mitigate it to the point where the buildup will take much much longer.


On my wife's cobalt for example-she gets tons of much blow by coming from the CCV system even with catch cans, I typically clean it every two oil changes (the TB) and while I'm at it clean the MAF as well. Hers is DBW and has that same lip, not to mention the 2.2 ecotec is notorious for blow by. In her car it got so bad that the valve was catching on the open and the close and stalling on deacceleration, and other times would cause hang ups when revs were falling or horrible idling.

I haven't pulled my Evora one yet and need to do so, hopefully in conjunction with a catch can installation soon. IIRC the 2GR-FE also has some history of putting a decent amount of blowby through the CCV system.

TBs are relatively easy to clean so it is definitely worth regular attention-and probably the solution to a lot of peoples issues.
Thanks invictusmaneo.. I will be installing a couple of air-oil-separators later today.
 

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Question for those with the Radium (or any brand) catch can setup: does it smell? The CC setup on my Audi smelled like sh!t. I love the decat exhaust smell, but that crankcase smell is no good IMHO.


Sent from my Autoguide iPhone app
 

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my wife's catch cans get filled with what looks like baby diahhrea and smells pretty awful as well...but I guess that's what happens when it has been through the system like that. Imagine that going back through the intake track?

I want catch cans ASAP on my Evora for that exact reason
 

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when you open the Catch Can to drain it in my case. Also sometimes the inherent smell is going to linger in/around the cans/intake tract. At least from what I've noticed.
 

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when you open the Catch Can to drain it in my case. Also sometimes the inherent smell is going to linger in/around the cans/intake tract. At least from what I've noticed.
Yes - mine was a closed loop as well with perfect vacuum pressure, yet it still smelled.


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Anyone have cleaning instructions for the throttle body and MAF for those with a radium cold air intake? I've always done this job with my own cars, so I'd like to do it for this one as well.
 

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Discussion Starter #15 (Edited)
It should be self explanatory. Most of this is common sense, but since you ask and I like to help:

1. remove maf sensor at the metal tube and carefully spray directly onto the sensor with maf cleaner solution. Don't get to close, spray from a few inches away. You don't want too much pressure on the sensor. Just enough to blow off dust and debris. Do not make make contact with the sensor or touch it in any way. Also while you're at it, clean the temp sensor on the side of the unit. Now set it aside and let air dry for a few minutes.
2. While the sensor is drying, remove hose around the large rubber connector that connects the pipe to the tb. then wiggle the hose out of place and push aside. Don't be scared, it's rubber, just push that hose out of the way.
3. use some choke cleaner (or if you don't have any use the MAF cleaner) to liberally spray into the TB around the butterfly valve. Then reach in with a cloth shop towel and wipe everything down: the flaps, the surrounding surfaces, especially the areas beyond the flap, where the gunk is. Get it all spiffy as best you can.
4. reinstall everything back into place.
5. Optional: you may want to inspect and clean any debris around the electrical connector on the TB as well. Some here have stated it has helped resolve some of their 'limp' mode issues.

Then have a beer :)
 
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