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IAC cleaning, calling for help! (follow up)


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23 replies to this topic

#1 frag

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Posted 30 July 2005 - 02:10 PM

HI!
Im in the process of cleaning my IAC. Slight idle roughness that other measures did not get rid off.
At this stage I have the whole body of the valve on the sink counter and have begun removing the top electric part (the one that controls the moving cylinger inside the valve) to get at the dirty cylinder and be able to clean it thoroughly. I removed the two philips screws holding the top grey plastic part.
The problem is the plastic electric part on top of the valve is tied to the cylinder's axle with what seems to be a coil spring somewhere. When I pull on this grey plastic part it slides off the vertical axle a bit but the spring resits its being removed entirely. I'm afraid that I will mess up something if I plull any harder.
Could someone that has done this on a similar model year car (95-96 2.2 L) give me some advice here please?
Thanks in advance.
By the way, I first did a search on this forum cause I knew IAC cleaning had been discussed here before, but found nothing pertaining to this problem.

#2 Olnick

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Posted 30 July 2005 - 02:55 PM

[It's been awhile since I did mine but I don't recall a spring or any kind of mechanical connection between the grey controller and the axle of the valve. I do recall a rather strong magnetic-like attraction that took a small tug to separate the two parts. Once the controller/head was off, the axle was free to rotate--a very sticky rotation until I spray cleaned the valve body and axle, then it turned loose as a goose.

Because of the magnetic attraction I assumed that the control head is sort of like a rotary solenoid to actuate the cylindrical valve through the axle.

Only thing I can think of is increasing that "gentle pressure" slightly adn see what happens (that's a lotta' help, right!)

Good luck and report back--now I'm anxious to know.

#3 frag

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Posted 30 July 2005 - 02:55 PM

One more info. Off the throttle body like it is right now, the valve is 1/3 open. Is this right?

#4 frag

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Posted 30 July 2005 - 03:01 PM

Olnick, what year is your Legacy? Just to evaluate the chances my IAC being similar or different than yours. It really feels like a spring but I'll look, and feel, again. By the way, as far as I can tell right now the moving half cylinder (for lack of a better term to describe it) seems to moves very freely inspite of the fact that its covered with a thin and rather hard to remove coat of dried up oil and crap. I'm beginning to question the wisdom of going any farther but i'm afraid I might not be able to stop at this point.

#5 Olnick

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Posted 30 July 2005 - 03:01 PM

One more info. Off the throttle body like it is right now, the valve is 1/3 open. Is this right?


Yes, I think so. That's about where mine was if I remember.

#6 frag

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Posted 30 July 2005 - 03:11 PM

Well you saved my day Olnick. It was indeed a strong magnetic field that felt very much like a spring. So i'm finishing the valve cleanup, will replace and will report back on the results. Tonight or maybe tomorrow.
Thanks again! Feels strange to be doing this with help from someone in Hawaii... Very small world in some respect.

#7 frag

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Posted 30 July 2005 - 03:20 PM

One last note before I return to the car. This magnetic field between the top control module and the valve cylinder stem is so strong that when I went to replace it, it pulled the part right off my fingers !
Thanks again Olnick.:)

#8 Olnick

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Posted 30 July 2005 - 03:44 PM

Humuhumunukunukuapua'a strikes again! Aloha!

#9 Olnick

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Posted 30 July 2005 - 04:02 PM

By the way, as far as I can tell right now the moving half cylinder (for lack of a better term to describe it) seems to moves very freely inspite of the fact that its covered with a thin and rather hard to remove coat of dried up oil and crap.


One more observation--my valve innards had a wet, oily gunk inside.
You might want to check the rubber hose that feeds air from the intake to make sure it's clear. Or maybe I need to check mine!

I have a '95 L by the way--I suspect that they're identical.

Alooooooha.

#10 frag

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Posted 30 July 2005 - 04:10 PM

Two more questions Olnick if I may.
1) I can't find the torque value to replace the valve body to the throttle body in Haybes. Do you have it by any chance?
2) Did you simply replace the grey plastic control module exactly where it was in the first place or did you make some adjustments after having replaced the valve?
About the wet oily gunk. Maybe you had a bad PCV valve or somehting. All I found in mine was a thin dry black coating that did'nt seem to interfere with the valve operation.
At least my mind is at rest concerning this valve and I'll go on looking for something else if this cleaning does'nt cure the roughness in the idle. Next willl probalbly be the throttle position sensor.

#11 Olnick

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Posted 30 July 2005 - 04:32 PM

Happy to discuss, frag.

1) No idea about the torque value--I'm one of those guys who just tightens until it feels "right!" Not good I know, but it's always worked for me (so far!)

2) Simply tried to replace it where it was. Figured the original placement was better than any finagling I might try. If you do try some adjusting let me know what kind of results you get.

Thanks (mahalo) for the PCV suggestion. Been meaning to do that and now you've given me the incentive!

As far as the TPS--I tried that and got thoroughly frustrated. The crummy pot-metal screws they used to mount it got chewed up so I gave up. Something else I need to get back to.

One thing that did help me is that I replaced the "engine coolant temperature sensor" just after I cleaned the IACV. But I knew it was bad because it threw a code. Between the two procedures the Legacy smoothed out tremendously.

Hope this helps a bit. And please do let us know if you sense any difference with your nice, clean IACV!

Aloha.

#12 frag

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Posted 31 July 2005 - 02:12 PM

IAC cleaned and reinstalled with a new gasket.
As far as I can tell, nothing as changed. That, of course, is almost good news: I was afraid to mess up things cleaning that valve.

Lets recap the initial problem and measures taken. Maybe someone can help.
> Problem: slight to moderate idle roughness. Idle is slightly lower than what it used to be at. Nothing like if the engine was running on three cylinder, rather 3 and 1/2 or 3 and 2/3 to use a comparison.
1) Plugs (NGK) and wires are new
2) Fuel and air filter have been replaced not long ago.
3) Throttle body and plate are clean.
4) IAC control module cheks out via Haynes method of testing it (9ohms between terminals 1 and 2 and terminals 2 and 3.
5) Coil tests OK.
6) MAF looks clean.
7) All vac tubes were inspected inch by inch and are like new.
8) I run injector cleaner (mild kind ) almost at evey other fill up.
9) I have checked all grounds and they are good.
EDIT
10) Both O2 sensors are almost new
11) The coolant temp sensor is 40K kilometers old only (2 years).

Revisiting the symptoms: When I start he car the idle goes to 1500 first like it always did. It then slowly decends to 1000. Up to that point idle is silky smooth (am I right in thinking that if I had valve problem, it would already show at that rpm?). This smoothness is still there until around 900 when a sligh roughness creeps in, when the idle settles around 680- 700 rpm, the moderate roughness I have previously described happens and stays.
Maybe its the effect of the genreal aging of the car and I will have to live with it.

WHAT HAVE i LEFT OUT? Would appreciate any opinion on this at this point.
Thanks in advance.

#13 Olnick

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Posted 31 July 2005 - 03:59 PM

Aw shucks! Sorry frag. Only other things I can think of are the TPS, as you mentioned, and maybe the Engine Coolant Temp Sensor. Lots of talk recently about them dying or getting weak but not throwing a code. About $20 IIRC, and might be worth a try.

At any rate, keep up the good work. You'll solve the problem eventually.

Aloha.

#14 Handtool

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Posted 31 July 2005 - 05:11 PM

Hmmm, O2 sensors? I replaced my front sensor with a universal unit that had a dedicated ground wire and noticed a smoother idle and better MPG's. Just a thought. Good luck!

#15 Olnick

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Posted 31 July 2005 - 05:18 PM

Good suggestion, Handtool. I did exactly the same thing recently and I too think it helped.

#16 frag

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Posted 31 July 2005 - 07:44 PM

Two good suggestions that make me notice I forgot to put in the «already taken measures» list that both O2 sensors habe been replaced recently and that the coolant temp sensor has been replaced a couple of years ago (around 40,000 kilometers ago).

The strange thing is that when I relase the throttle the idle is smooth for the first 5-10 seconds and then slowly gets a little slower and rougher.

#17 Olnick

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Posted 31 July 2005 - 08:25 PM

This is getting well beyond my meager capabilities now frag! Could it be in the fuel delivery system--pump, regulator, nozzles?

#18 frag

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Posted 01 August 2005 - 07:14 AM

This is getting well beyond my meager capabilities now frag! Could it be in the fuel delivery system--pump, regulator, nozzles?


I'll keep exploring but I suspect it might be a collection of small geriatric ailments, just like with my own body... :brow:

#19 cookie

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Posted 01 August 2005 - 11:42 AM

Is there anyplace you can get it on a diagnostic machine? Even a small vacum leak could cause something like this too.

#20 frag

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Posted 01 August 2005 - 11:48 AM

Is there anyplace you can get it on a diagnostic machine? Even a small vacum leak could cause something like this too.


A diagnostic machine would detect a small vac leak?

#21 cookie

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Posted 01 August 2005 - 01:05 PM

a lot of problems. I'm sure more modern ones can do more. It counted the timeing and indicated weak cylinders. Once you found a weak cylinder then you did another series of tests like a leakdown on the same machine.
I'm not sure how they test fuel injection now as I have mostly worked on FI on diesels. These were pretty much mechanical and you killed a cylinder with a screwdriver by holding the valve open. If the engine speed did not change you knew it was weak. Another way was to crack the injector fuel line, but that was messy.
I guess this depends on what you local shop has available for equipment and how good the person using it is.

#22 frag

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Posted 01 August 2005 - 08:16 PM

Thanks cookie.
For the time being and for lack of a better method, I tried an oldie and connected a vacuum gauge to a vacuum port (intake runner for cyl no 3).
I get 22 inches of mercury and absolutely steady. When I do the acceleration (2500 rpm) deceleration test the gauges jumps up 4 inches when I release the throttle and slowly gets back down.
So everything seems perfect mechanically (rings, valves, vacuum system in general). I also sprayed WD40 around the intake manifold gasket with no effect.
The last resort will be a thorough upper cylinder cleaning. Maybe it's just carbon in some of the cylinders.

#23 cookie

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Posted 02 August 2005 - 10:10 AM

if it was the valves. Is it possible there to pull the injectors and have them tested?

#24 frag

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Posted 02 August 2005 - 10:24 AM

if it was the valves. Is it possible there to pull the injectors and have them tested?


I might try that eventually. Thanks for the suggestion.




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