How to clean your IAC (Idle Air Controller) valve

No 'Check Engine' light ...
No codes ....

The 'surging' happens in 1st and 2nd gear ..... at low speed. Will be idling down the road in 1st, and when the throttle is barely touched, it will surge ahead. Very aggravating. Tried this procedure on a steeper adverse (under load) and it was less apparent. On another forum, it was suggested that a throttle return spring may help.
Ideas ?
 
Hmmm, probably worth starting a new thread over. Whenever there's no check engine light I hate to guess, because then I feel like I'm firing shots in the dark. A throttle return spring may very well be a cheap and easy place to start though!
 
The throttle lever has two return springs on it from the factory... one is a conventional looking very visible spring used as a backup, the main throttle return spring is coiled around the shaft that the valve plate opens around and is kinda hidden. Adding a third spring isn't going to do a thing unless you have the unlikely possibility of both OE springs having gone bad.

I'm not sure what is causing the surging but I'll just about guarantee it would not be helped/cured by adding a third throttle return spring. Perhaps the Throttle Position Sensor has gone bad, I dunno. I assume you have cleaned the IAC though I can't immediately see that as a likely source of the problem.
 
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Oh, were we talking about adding a third throttle return spring? Yeah, I can't see how that would help.

I'm inclined to agree with Jerry about a possibly bad TPS or some other sensor.
 
Just wanted to say I have completed the IAC Valve cleaning and furthermore the cleaning of the entire Throttle Body and all of its components and I would like to give Chris a shout out for a great write up and insight on this topic for a newcomer to follow.

I had 150k miles on my TJ and the IACV was completely black, the housing was filthy, and so was the inside of the throttle body. I took it apart, emptied a can of CRC into it, brushed the grime away, and i'm back to bare metal again!

There is a noticeable idle drop on my gauge, not that I was idling high before but it is absolutely idling lower and breathing a little better. This was an easy job that any novice could handle with basic tools and common sense. Good maintenance, good practice.

Next is spark plugs!
 
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Yep, the IAC is often overlooked and should be cleaned periodically, especially since all it costs is a can of cleaner.
 
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IMG_0390.JPG
 
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Before I take apart my Throttle Body and my IAC sometime this week - I just want to make sure: the throttle body indeed does have a gasket, I have it sitting in my cart on Amazon, but the IAC looks like it has its own o-ring already on it - correct?
 
Nashorn101 said:
Before I take apart my Throttle Body and my IAC sometime this week - I just want to make sure: the throttle body indeed does have a gasket, I have it sitting in my cart on Amazon, but the IAC looks like it has its own o-ring already on it - correct?
Click to expand...
Yes there is a gasket between the throttle body and intake manifold. And yes the IAC will have an o-ring on it.

That said, I don't believe there's any need or benefit to removing the throttle body to clean the IAC. And seldom does the IAC actually need to be removed from the throttle body to clean it very effectively. I feed TB cleaner into the TB while the engine is idling and the IAC will draw the TB cleaner in through itself, cleaning itself in the process. It will not suck the TB cleaner in unless the engine is idling, so don't rev the engine during the cleaning process. The engine will die repeatedly during this process since the cleaner is flooding the inside of the IAC but that's fine and actually good, it gives the cleaner more time to clean. Just restart the engine after it dies.

I try to use a third of the can cleaning the IAC at idle RPMs, then finish the can by spraying the inside of the TB while revving the engine a bit. Every so often I'll let it idle and spray more cleaner at the passage inlet slot the IAC draws its air through, just to make sure the IAC is perfectly clean.

The IAC's air passage inlet is just above the throttle body's valve plate in this illustration...

TB & TPS Sensor Locations.jpg
 
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Jerry Bransford said:
Yes there is a gasket between the throttle body and intake manifold. And yes the IAC will have an o-ring on it.

That said, I don't believe there's any need or benefit to removing the throttle body to clean the IAC. And seldom does the IAC actually need to be removed from the throttle body to clean it very effectively. I feed TB cleaner into the TB while the engine is idling and the IAC will draw the TB cleaner in through itself, cleaning itself in the process. It will not suck the TB cleaner in unless the engine is idling, so don't rev the engine during the cleaning process. The engine will die repeatedly during this process since the cleaner is flooding the inside of the IAC but that's fine and actually good, it gives the cleaner more time to clean. Just restart the engine after it dies.

I try to use a third of the can cleaning the IAC at idle RPMs, then finish the can by spraying the inside of the TB while revving the engine a bit. Every so often I'll let it idle and spray more cleaner at the passage inlet slot the IAC draws its air through, just to make sure the IAC is perfectly clean.

The IAC's air passage inlet is just above the throttle body's valve plate in this illustration...

View attachment 14111
Click to expand...

Wow thanks for that! I was wanting to take the throttle body in addition to the IAC to clean it as well. But, you are telling me that you can just spray TB cleaner into the throttle body and let the engine do all the cleaning?
 
@Head Lice, I also am having a surging problem in my Jeep.

At 1st gear my Jeep feel's like its accelerating, then slows down, accelerates again, and slows down.

I just sprayed a whole bottle of throttle body cleaner in my throttle body as well as the idle air vent, and my engine runs much smoother I can clearly tell, but the surging still is there. Like you, I probably will change out my spark plugs next.

But the whole "hit the gas and my Jeep takes off in 1st", I always thought that was the nature of a Manual transmission (at least that's what I have, not sure about you sir) as well as the fact that you have a ton of torque in 1st gear.
 
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