Engine stalling, need new "Auxilliary Idle Control Valve"?

[SVXdc]

A couple of nights ago, my '96 started stalling if I did not keep the revs above ~1000rpm. In order to crank it, I had to keep my foot on the gas.

I read the ECU [correction: TCU] fault code (using the shift D/3/2/1 manu-button technique) and got code 23 "Engine Revolution Sensor".

Does anyone have any further information about this fault?

I've taken it to a Subaru dealer, and they've determined that I need a new "Auxilliary Idle Control Valve" for about $244 plus 2hrs labor.

I tried looking up the part number they gave me (14467AA02A) on SubaruParts.com, but can't find it.

This thread started by Landshark (http://www.subaru-svx.net/forum/showthread.php?t=10747) from a few years back talks about the "auxilliary idle air control valve". Is that the same part? Beav said it should only need to be cleaned, not replaced. That fix would sure make me $244 happier.

[Earthworm]

You scanned the TCU fault code...not the ECU code. Does the check engine light come on or stay on? Find someone with an OBD-II reader to confirm and engine codes.

[SVXdc]

The "check engine" light did not stay on. I think it came on while the engine was stalled -- it seemed to be the normal mode for when you turn the key to "on" but have not cranked the engine, where most of the dash indicators light up.

The dealer did use an ODBII scanner. The error message was slightly different than the above, but similar (I don't remember the exact wording it showed). It was still somewhat non-specific as to the cause.

[svx_commuter]

Cleaning the throttle body comes to mind. I think you don't have any codes to care about. The CE would be on if a sensor failed or misfired occured for OBDII.

[SVXRide]

Beav's got it right! Pull the TB off and then pull the AICV off the bottom of it. Clean both with TB cleaner, let dry, and reinstall
-Bill

[oab_au]

Beav's got it right! Pull the TB off and then pull the AICV off the bottom of it. Clean both with TB cleaner, let dry, and reinstall
-Bill

Bill that is fine for the Idle Air Control Valve,:) but it is the Auxiliary Air Valve that is the problem. It is under the left hand, rear of inlet manifold. The inlet hose, to the AAV, runs off the left hand side of the air box that connects to the throttle bodies. If you pull the hose off the air box, you should be able to blow through it when the engine is cold. If you can't, the valve is stuck. Spray some carb cleaner into the AAV to unstuck it. :)

Harvey.;)

[SVXRide]

Bill that is fine for the Idle Air Control Valve,:) but it is the Auxiliary Air Valve that is the problem. It is under the left hand, rear of inlet manifold. The inlet hose, to the AAV, runs off the left hand side of the air box that connects to the throttle bodies. If you pull the hose off the air box, you should be able to blow through it when the engine is cold. If you can't, the valve is stuck. Spray some carb cleaner into the AAV to unstuck it. :)

Harvey.;)


D'oh! I've got to get more sleep before posting:rolleyes::p
-Bill

[SVXdc]

... it is the Auxiliary Air Valve that is the problem. It is under the left hand, rear of inlet manifold. The inlet hose, to the AAV, runs off the left hand side of the air box that connects to the throttle bodies. ...

I have not been able to find a diagram that shows the Aux. Air Valve.

But in this diagram...

http://www.subaruparts.com/subaru.diag/2A/i073A-1.gif

(the "Air duct" diagram, showing the "Boot-air intake")

Is the inlet hose to the AAV that you are talking about the hose labeled H512191 or the short tube labeled "refer to fig. 82A" ?

[billb]

If you look in my locker you will see a writeup on the Aux. Air Valve and the Idle air control valve (usually called the IAC). There's a lot of photos there too. It explains the valves, where they are and how to clean them. Briefly, the Aux. air valve is only open when the car is cold. It allows extra air in while the engine is cold. After the car warms up, it closes down. As it closes, the idle speed drops. When the valve has completely closed, the engine should idle at 610 rpm.

If your problem is only when the engine is cold, it could be the Aux. air valve.

The IAC holds the engine idle at 610 rpm after warmup. It can get gunked up and be cleaned.

http://www.subaruparts.com/subaru.diag/2A/i073A-1.gif
The diagram you referenced above doesn't show either one of these valves.

[SVXdc]

Found the correct diagram and the part the dealer said I need to replace...

Image: http://www.subaruparts.com/subaru.diag/2/i036-A.gif

Page on SubaruParts.com, category 036A-1 "Water Pipe (1)" (http://www.subaruparts.com/diag/?model=2A&year=1996&style=4WD&body=&scn=0&category=036A-1) (now requires registration/login)

Part number 14467 "Valve assembly-auxiliary air" $110.76

Although the diagram for the 92 is slightly different, the same part is listed there too.

I don't see how this aux. valve could be causing my stalling problem. After re-reading Jason's post in the "Confused" thread (http://www.subaru-svx.net/forum/showpost.php?p=404771&postcount=7), it sounds like the 'primary' valve is more likely the culprit. Can any other experts confirm?

Added: Problem persisted even after engine was hot.

[billb]

I have not been able to find a diagram that shows the Aux. Air Valve.

But in this diagram...

http://www.subaruparts.com/subaru.diag/2A/i073A-1.gif

(the "Air duct" diagram, showing the "Boot-air intake")

Is the inlet hose to the AAV that you are talking about the hose labeled H512191 or the short tube labeled "refer to fig. 82A" ?

Nope. It comes off of the other one, where it says Fig. 36.

[SVXdc]

Is the inlet hose to the AAV that you are talking about the hose labeled H512191 or the short tube labeled "refer to fig. 82A" ?Nope. It comes off of the other one, where it says Fig. 36.Thanks. After I finally found diagram 36 I figured that out.

If you look in my locker you will see a writeup on the Aux. Air Valve and the Idle air control valve (usually called the IAC).Ah! I hadn't noticed the Word doc before. That helped a lot. Wish I had found that before I went to the dealer.

One question I still have: Where does the inlet hose to the (primary) Idle Air Control Valve come from? I'm not seeing any stubs for it on the "Air Intake Boot" page (fig. 073A), or the "Air Intake" page (fig. 071K).

[billb]

One question I still have: Where does the inlet hose to the (primary) Idle Air Control Valve come from? I'm not seeing any stubs for it on the "Air Intake Boot" page (fig. 073A), or the "Air Intake" page (fig. 071K).

Look at my photo 10 for a picture of the tube attached to the IAC valve. The open end of that tube can be reached by standing on the passenger side of the car and reaching down between the main air intake tube and the firewall. It stubs off of the air tube back there. I didn't take a photo of it in the car because you can't really see it very well.

[SVXdc]

... [from the] passenger side of the car [reach] down between the main air intake tube and the firewall. It stubs off of the air tube back there. ...That helped -- I looked more closely at the Air Duct diagram (073A) and noticed the "Refer to Fig. 050A" above the Air Boot. Figure 50, "Intake Manifold," shows the hose flying in space (and the hose has no connection with the parts on figure 50 otherwise).

[cdigerlando]

When you find it, try cleaning it up again before buying a new one. There is not much too this part to go wrong. It does seem like that is what the problem is with the car from the symtoms you decribe.

[billb]

By the way, you can try cleaning the IAC without pulling off the throttle body. When you find that inlet hose that goes to the IAC, pull it off of the main air tube and spray throttle body cleaner into it. You obviously can't see if it was dirty and you're cleaning anything, but it's a cheap and easy try at a fix.

If you have to hold your foot on the throttle to keep the car running, it may very well be that the IAC is not letting any air through. If the problem persists after the car is warmed up, it is not the Aux. Air Control valve.
Bill

[SVXdc]

The dealer already has my car. If I had found all of this out before I took the car in, I would have tried that myself.

At least I stopped them from ordering an Aux Valve (the part number I listed in my first post). That bugs me a bit that they thought replacing the aux valve would have fixed the stall problem.

Since they have my car now (and I'm having them do a 90K service too), I've asked them to try just cleaning the (primary) Idle Air Control Valve. The tech is going to remove it to look at it, and will let me know if he thinks cleaning it will work or if there appears to be something more serious wrong with it.

[SVXplorer]

Out of curiosity, what was the cause of your stalling? You didn't post an outcome.

My car is now having similar problems (dropping and fluctuating rpms and stalling only on braking, not while coasting, no CEL, starts again easily), so any added input would be very helpful.

[SVXdc]

The stalling problem was solved after the dealer cleaned the (primary) Idle Air Control Valve. They charged me 1/2 hour labor (on top of the 90K service).

It didn't occur to me until it was too late to ask them to save the old air filter. I would have liked to have seen how dirty it was.

Sorry for not posting a follow-up sooner.

[billb]

That's a pretty excellent outcome. A half hour of labor isn't bad at all.