Manual gearbox Stall.

[icingdeath88]

Originally Posted by Dessertrunner

Okay being Saturday morning I decided to do the adjustment to the idle valve. Removed the throttle body and pulled the Idle valve to adjust. I have no idea if I am doing the right thing or not but I unscrewed the magnet coil and rotated it till the baffle was just closed. I figure the ECU will handle any further adjustment. My aim is to just put the baffle in the right position so the ECU can again adjust the idle.

I have not started the car but will come back to you with a update.

Take pics if you can still How clean did the valve look, out of curiosity?

If you find that it works well, then I will be following suit.

[Dessertrunner]

Harvey How much work is it to use one of the PIC chips. Do they have analogue port 2 input and two output?

Tony

[oab_au]

A bit more that switching a resistor in. It would be better to retain the ECUs control and aim at the particular problem. Using another unit to do the ECUs job is harder.

Harvey.

[Dessertrunner]

All I wanted to do with the PIC was to watch for a close valve signal coming throught the wires and ignore it.
I did a study into how the valve work a couple of years back and if you remember our old mate gave me grief saying I was wrong till he checked the functioning of the valve.

As I remember one wire opens the valve one closes and the other is the second wire to the coil for the coils. The PIC would just watch the voltage coming down the close wire and ignore it if it went above a predetermined level.
By the way the ECU only shuts the air when the engine temp is at operation level. Below that it won't shut the valve.


I drove for a week with the adjusted throttle openings and the car never stalled once and that includes all the driving around the paddocks etc (mud), overal it was easier to drive. The down side was the idles was around 1,400 to 1,700rpm and that is why I want to change the idle control valve.

Tony
Tony

[oab_au]

Originally Posted by Dessertrunner

All I wanted to do with the PIC was to watch for a close valve signal coming throught the wires and ignore it.
I did a study into how the valve work a couple of years back and if you remember our old mate gave me grief saying I was wrong till he checked the functioning of the valve.

As I remember one wire opens the valve one closes and the other is the second wire to the coil for the coils. The PIC would just watch the voltage coming down the close wire and ignore it if it went above a predetermined level.
By the way the ECU only shuts the air when the engine temp is at operation level. Below that it won't shut the valve.


I drove for a week with the adjusted throttle openings and the car never stalled once and that includes all the driving around the paddocks etc (mud), overal it was easier to drive. The down side was the idles was around 1,400 to 1,700rpm and that is why I want to change the idle control valve.

Tony
Tony

Yeh I see what you mean, but the valve is held between the two electro magnets, its a 'see saw' ballancing act. As one is increased the other is reduced.
Both are driven all the time to hold the vane steady. Cutting one out would make it swing to the oppersite one.
I think reducing the drive would be smoother than cutting it out.

Harvey.

[oab_au]

Originally Posted by Dessertrunner

I drove for a week with the adjusted throttle openings and the car never stalled once and that includes all the driving around the paddocks etc (mud), overal it was easier to drive. The down side was the idles was around 1,400 to 1,700rpm and that is why I want to change the idle control valve.

Tony
Tony

Tony under what conditions did it stall before. I guess it didn't when the clutch is driving. Just when you push the clutch in to change gears, or clutch in and coasting??

I am just trying to get an idea of what the actual problem is, as I have never driven the car.

Harvey.

[Dessertrunner]

Harvey I agree that you could balance it between the two voltages I would'nt cut it out just reduce it.

Okay this is my 2 bob's worth as to when it happens and the condiations.
- Car must be at operational Temp, Some were above 95C
- Car must be moving (ECU is picking up speed sensor)
- Throttle must be lift off resonable quickly.
- The clutch has no effect, you can cause the stall coasting down a hill provide the above condiations are meet.

Hope that helps, when I looked at it before I found that the valve was full closing, I did this by extening the wires from the engine to a valve I had stiting on the seat inside the car to be ble to watch it.
Tony

[oab_au]

Originally Posted by Dessertrunner

Harvey I agree that you could balance it between the two voltages I would'nt cut it out just reduce it.

Okay this is my 2 bob's worth as to when it happens and the condiations.
- Car must be at operational Temp, Some were above 95C
- Car must be moving (ECU is picking up speed sensor)
- Throttle must be lift off resonable quickly.
- The clutch has no effect, you can cause the stall coasting down a hill provide the above condiations are meet.

Hope that helps, when I looked at it before I found that the valve was full closing, I did this by extening the wires from the engine to a valve I had stiting on the seat inside the car to be ble to watch it.
Tony

OK thats good, and you don't have any of the lines, P,N connected to the ECU, so the ECU thinks that you are in gear?

Harvey.

[Dessertrunner]

Thats correct.
Just drove to work (I am now on a different computer) about 30k's it ran well and idled correctly, when I first started it the ECU didn't want to let it idle (shut it down) I realized the battery had to be taken off so the ECU relearnt also I opened the throttle body a 1/3 of a turn on the screw.

Okay here is were I am at,
The throttle body is open just enough that when the Idle valve trys to kil the engine it can't.
Idle control valve has been closed up till it was close to just fully closed.
Removed battery termial to reset ECU and did some slight adjustments to throttle body butterfly.

Thats it I may need to do some more throttle body adjustment but we will see.

Result,
Car is idleing perfectly,
It nolonger (SO FAR) stalls even at operational temp etc.
Low end power is a lot stroger when you pull away it nolonger feels as if it will stall.
Only time well tell over the next month but given what I see so far I won't be going back to the way it was.

Have a great day all.
Tony

[Conn SVX]

Ok so now sum it all up to what others can do. Mine is finest I do not understand the problem but it does sound annoying .

[oab_au]

Tony I can see that you are getting around the problem, and that I have been pissing around in the wind, trying to find a solution to a problem that I have never experienced.
You have suppled the clue that has been missing all along. I have never seen the throttle mentioned in any of the reports that I have read over the years I have been looking at the problem. Your 2 bob’s worth gave me the clue that ties the problem to a cause.

Okay this is my 2 bob's worth as to when it happens and the conditions.
- Car must be at operational Temp, Some were above 95C
- Car must be moving (ECU is picking up speed sensor)
- Throttle must be lift off reasonable quickly.
- The clutch has no effect, you can cause the stall coasting down a hill provide the above conditions are meet.

Hope that helps, when I looked at it before I found that the valve was full closing, I did this by extending the wires from the engine to a valve I had sitting on the seat inside the car to be able to watch it.

The ECU has the function that when you lift the foot off and let the throttle close completely, it turns the fuel injection off and closes the air off. This is to prevent the Hydrocarbon emissions that would be caused.

When the engine is running the inlet manifold is coated with wet fuel, when the throttle is completely closed, the fuel is vaporised by the high vacuum, and pulled into the chamber to burn as a rich mixture. When we had carburettors, we used a dash-pot on the throttle lever, to slow the forming of the high vacuum.
With fuel injection, we cut the fuel off, to prevent feeding more fuel into the vacuum, we also cut all the air off, to prevent the vaporised fuel in the manifold from being sucked into the cylinder. This action solves the Hydrocarbon emissions.

In the SVX, the fuel and air cut happens when the ECU sees the ‘0.5V closed throttle‘ signal on a revving engine. The fuel and air are turned back on when the rpm gets to about 1200/1600? Rpm to bring the engine to a smooth idle. I don’t know why it is not catching the engine to bring it to idle in your case, just letting it stall, but I am sure that if the throttle was not dropped closed, but was closed down slowly, the ECU would not do the fuel/air cut, it would just follow the engine down to idle.

If we were to fit a dash-pot off a carburettor to the throttle lever, to slow the last few degrees of the throttle closing, the ECU would not see the 0.5V signal on a revving engine, and I think the problem would not happen.
What do you reckon?

Harvey.

[Dessertrunner]

Joe found a old post for me were I figured out how the valve works. Here is the link.
http://www.subaru-svx.net/forum/show...t=idle+control

Update,
I have driven the car about 250k since adjusting the idle control valve.
In short it hasn't missed a beat, starts and idles great. When its cold the ECU and cold valve adjust to raise the idle, When it warms up the ECU adjust the idle back to around 800 rp, when you turn the AC on the ecu rasies the idle to compersate.
When you lift your foot off the throttle you can see the the Idle Control Valve have a go at killing the engine but it doesn't.
When you pull away from a standing start I nolonger have to feather the throttle to stop the car stalling. I have a manual Lberty and the SVX now behaves very simlar when taking off.

It short so far so good, I will keep you posted but I feel sure the problem is solved. When others try it we may find smarter adjustments to may the change even better.
Will keep you posted in the future.
Have a great day & you got to love the SVX.
Tony

[Dessertrunner]

Hi Harvey you posted when I was typing the last comment,
What you say makes sense and now I have stopped the ECU from cutting the air it burns the waste fuel till the injectors start again.

. I don’t know why it is not catching the engine to bring it to idle in your case,

I personally beleive the valve doesn't open fast enough after closing and also has closed far to far so the time it take takes to fully close and open again is enought to kill the engine due to lack of air.

Any way I am happy I was going to drill in a adjustment screw to act as a stopper on the butterfly on the Idle Control Valve but figure why bother better to do what I have done so far it works. I have a million job backed up at work so unless the current fix deosn't work I am going to leave it at that.
Tony

[oab_au]

Yes we seem to do the same time posting a bit. Takes me a while to write it and post,to find that you have done the same thing.

OK no worries as long as you have a fix that is the main thing. I am just sorry that I did not see this way, a long time ago.

Cheers mate .
Harvey.

[Dessertrunner]

Stalling is back, I need to get my head around it and come back to everyone later.
Tony