Trouble starting when cold

[SVX_Norway]

I have a 92 SVX starting to trouble. It happens when cold, it starts but dies just after. When I depress the gas pedal a little it will not stop, but is running rough, sounds like it misfires.

The check engine lamp comes up now and then, and I tried to read out codes.
I counted 6 codes, and the first one is 31: throttle position sensor.

Could this be the one?

[icingdeath88]

I think it could be that.

Here's the how-to: http://www.subaru-svx.net/photos/user.php?How-To|14267

[oab_au]

Originally Posted by SVX_Norway

I have a 92 SVX starting to trouble. It happens when cold, it starts but dies just after. When I depress the gas pedal a little it will not stop, but is running rough, sounds like it misfires.

The check engine lamp comes up now and then, and I tried to read out codes.
I counted 6 codes, and the first one is 31: throttle position sensor.

Could this be the one?

Hi Mate, If you got 6 different codes, I would clear the memory, and check for the codes again. Some may be old ones that are not present now.
I would look for a code 21.

Harvey.

[SoCal LS-L]

Would you mind listing the codes so we can see what they are?

[SVX_Norway]

The codes in the order
1: 31, throttle position sensor
2: 13, cam position sensor
3: 11, crank angle sensor
4: 35, purge control solenoid
5: 34, EGR solenoid
6: 24, air control valve

I tried to clear codes by using both blue wires and then start the car, but it remains the same.

[oab_au]

Originally Posted by SVX_Norway

The codes in the order
1: 31, throttle position sensor
2: 13, cam position sensor
3: 11, crank angle sensor
4: 35, purge control solenoid
5: 34, EGR solenoid
6: 24, air control valve

I tried to clear codes by using both blue wires and then start the car, but it remains the same.

It would be very unusual for all those faults to occur at once.
I would check for a grounding problem, like the wire that runs from the back of the engine to the firewall just below the Igniter unit, it plugs into the firewall.

Harvey.

[SVX_Norway]

Finally I managed to clear the codes, I had to drive some minutes before the check engine lamp started the steady blinking.

The fault came back after a while, and now is the only code nr. 24: Air control valve/by pass control valve. Anyone had trouble with this one? Should I just order a new one, or could it be cleaned/fixed?

Karl-Ivar

[svxistentialist]

Karl-Ivar

Sorry to hear about your problem, but it is good you have narrowed down the problem.

It is very likely you will just need to replace the By-pass Air Control Solenoid Valve.

However, before you do that it is more usual to check all the connections between the valve and the engine computer [ECU] Work through the troubleshooting charts for Code 24 on the enclosed links:

Diagnosis

Check connectors and voltage

OK?

Joe

[StelthSvx]

THIS bugger is under the manifold. Mine decided to go bad a month AFTER my engine reseal(engine out of car). So i manage to change it with manifold ON......by removing intake snorkus on going in from behind....there are 2 bolts holding the valve into block. Took a while but i manged to do this without removing manifold.... good luck

[svxistentialist]

Thanks for the pic Stelth.

If you don't mind my saying so, owners who have had an SVX since new in '92 are a very rare crew. My friend Ron also in California is another, but very few people keep a car for such a long time.

Thank you for your loyalty.

Joe

[SVX_Norway]

Thanks guys! I located it today, and disconnected it to see what happened. Did not notice any difference, but will let it be disconnected and see what happens when the engine is cold. (had been started already today).

Did also find a vaccum line that was loose, to the left of the air control valve, under the intake manifold. Dont know what purpose it has, was another one right beside it.

[svxistentialist]

Good plan.

Here is more information:

Changing the PCV valve

Joe

[JDW-SVX]

You should be aware that there are actually two valves that control the amount of air that bypasses the throttle plates at idle.

The valve shown in the photo is the Auxiliary Air Control Valve - and it is not directly controlled by the ECU. That valve is fed a constant 12V supply from the fuel pump relay whenever the ignition is on, and inside the valve, a bi-metallic strip gradually reduces the air flow through the valve as it warms up. The ECU cannot monitor that valve, as it has no direct connection to it, and a fault in that valve does not trigger an ECU fault code.

That valve is only used to keep the engine idle speed higher than normal for a cold start.

The other valve is known as the Bypass Air Control Solenoid Valve - and it would most likely be the one that you need to clean, or replace. It is located directly underneath the throttle body, and consists of a continuously variable solenoid valve that the ECU controls directly in order to regulate the engine idle speed.

Note that the Auxiliary Air Control Valve has a 2-pin connector, and the Bypass Air Control Solenoid Valve has a 3-pin connector.

In my experience, the ECU can often set a fault code for that valve if it is sticking, or clogged. The ECU commands the valve to open or close, but if it sees no corresponding rise or drop in idle speed, it knows that there is a fault with the valve, and sets the fault code.

I would recommend cleaning the valve out before replacing it.

Jason.

[SURTEESS]

AAV is actually a bi-mettalic strip that is controlled by 12v supply - causing the shutter to close or open depending on engine temerature, allowing more or less air to flow through the opening.

This sometimes get clogged-up with oil (as was case with mine) when the dipstick o-ring issue reared it's ugly head.

Subaru said new one costs approx NZ$50.00 + fitting - in their mind it was a non-servicable part, so I bought new one & spent the best part of 3 hours swapping it over.

When I cleaned up old one (using white spirits) it worked fine, just shorted across battery for a few seconds to see the shutter close) - so now have a spare for next time.

It also ment that during start-up a puff of blue smoke occured (not every time) - hence oil in the exhaust area of AAV (Aux Air Valve).

[SVX_Norway]

Anyone know the location of the Bypass Air Control Solenoid Valve, maybe a picture showing it?

Karl-Ivar