Manual gearbox Stall. - Page 2

TomsSVX · #16 01-31-2012, 04:17 AM

Thats just the butterfly stop... creating a vaccum leak... which is why it doesnt stall...

Mt cars have different mapsprogrammed for this reason... amongst others... idle adjustment does not always fix it.

@bill i will be passing through in april goin to myrtle

Conn SVX · #17 01-31-2012, 08:05 AM

When you start the car the next morning will the idle be high for about 30 seconds?
My 1994 has a 2,000 rpm idle when first started and them drops to 700. I have no stall problem . Feels like every other 5 speed Subaru I have owned. As I mentiomned earlier I can drop the idle with the clutch to about 300 with no stall.
Is this only a problem with the. 1995 and newer ones ?

Dessertrunner · #18 01-31-2012, 10:35 AM

Quote:

Thats just the butterfly stop... creating a vaccum leak... which is why it doesnt stall...

Its not a vacum leak, how the hell do they adjust the revs on a old carburetor?
They do it by opening or closing the butterfly.

Currently when a SVX engine is at operational temp and on idle the only place the engine can get air is through the Idle control valve. When you have the engine reving and lift of the throttle this valve fully closes cutting all air to the engine. The period of time its actually closed will determine if the engine will stall or not.
The valve is a magnet and has a open & close magnet. This approach is a bit hit and miss and can cause the car to somtimes stall mainly because the magnets aren't very accurate.

It takes 2 seconds to make the change so I would hope people will at least give it a go and see if I am right or wrong for themselfs.

Tony

oab_au · #19 01-31-2012, 04:27 PM

This problem is really confined to the manual trans, it does not happen with the auto, why?

I looked at this problem a while ago, and I am of the opinion that it is due to having the clutch pedal linked to the Neutral wiring.

If we look at how the auto does it, there are two connections to the ECU, that are grounded when the shifter is moved to either Park, or Neutral. When neither of these two pins are grounded, the ECU knows that the car is in gear.
In my opinion the ECU has a different strategy depending on what the car is doing. When it is in P or N it would have a different starting, idling routine, when you pull it into gear, it bumps the idling speed up to handle the load of the converter stall, and runs the active driving and idling routine.

With the clutch pedal switch grounding the Neutral pin at the ECU, every time that you push the clutch in, the ECU goes into the Neutral Idling routine, where it can't handle the extra loads that a 'still moving' car has.

I think if this arrangement was changed so that Neutral was only grounded for starting, and the two inputs to the ECU were open all the time the car was running, it would be able to handle the idle under all the conditions that a running car has.

Harvey.

TomsSVX · #20 01-31-2012, 06:41 PM

Its a controlled "leak". I know ur because i had tried it several times on mts with varied results...

Harvey, even switching to neutral without using the clutch can cause the stall too... so while your idea holds water it might not be the whole of the solution.

I have found the stock ecu does not like operating outside of conditions of what it was programmed for... why this was such an issue i can only relate to my issues with load swing managment using the stock ecu. Never had stall issues using stock components with the hydra so i cannot say for sure how to fix it with the stock ecu in place

Tom

Dessertrunner · #21 02-01-2012, 03:04 AM

I accept that the ECU is doing some strange things and it maybe more complicated then I first thought.

As regards netrual I have bypassed it and its not wired throught the clutch.

I have adopted a different plan but along the same lines. Given what I saw today the valve is causing the engine to die because is killing air. What I have now done is block the hose feeding air to the idle control valve and then set the butterfly so the car will still run. Then unblock the hose, now the idle is far to high 1,600rpm) but I want to find out if that has killed off the stall problem first.
I will do trails for a couple of days to see how it goes then I will work out what needs to be done to the valve.
Will keep you posted.
Tony

huck369 · #22 02-01-2012, 05:27 AM

Quote:

Originally Posted by oab_au

This problem is really confined to the manual trans, it does not happen with the auto, why?

I looked at this problem a while ago, and I am of the opinion that it is due to having the clutch pedal linked to the Neutral wiring.

If we look at how the auto does it, there are two connections to the ECU, that are grounded when the shifter is moved to either Park, or Neutral. When neither of these two pins are grounded, the ECU knows that the car is in gear.
In my opinion the ECU has a different strategy depending on what the car is doing. When it is in P or N it would have a different starting, idling routine, when you pull it into gear, it bumps the idling speed up to handle the load of the converter stall, and runs the active driving and idling routine.

With the clutch pedal switch grounding the Neutral pin at the ECU, every time that you push the clutch in, the ECU goes into the Neutral Idling routine, where it can't handle the extra loads that a 'still moving' car has.

I think if this arrangement was changed so that Neutral was only grounded for starting, and the two inputs to the ECU were open all the time the car was running, it would be able to handle the idle under all the conditions that a running car has.

Harvey.

This make sense, but none of the 5-speeds I've done suffer from this.....maybe just the difference in how well the IAC is functioning,

Dessertrunner · #23 02-01-2012, 06:57 PM

The 90 to 99 liberty cars have a simular idle control valve but I don't know if the bolts pattern is the same as ours. Anyone out there can check for me please?
Tony

Dessertrunner · #24 02-07-2012, 08:17 AM

Okay I have driven for a while with the base line idle controled from the butterfly on the throttle body. The car doesn't stall at all now, the negitive on this is that the idle is siting at 1,700rpm.
What I need to understand is why all other subarus with simlar valves have bypass pipes http://www.ebay.com.au/itm/90-99-SUB...item2318e63bd5
are those pipes on the side to set base line idle?

The issue as I see it is that the existing valve on the SVX closes completly and kills all air. For what ever reason the ECU does it just as Tom has suggested. What I now need to do is prevent that happening by either puting a adjustment screw to stop the valve fully closing or instal a bypass to control the bottom end revs (bottom 600rpm) and adjust the valve back so it just deals with the finer adjustment.

My first choice will be to back off the valve and leave the butterfly to do bottom end. Once I have proven the concept I will consider how best to go forward.

Got to say I can see the light and I expect the issue solved in the next month.
Tony

icingdeath88 · #25 02-07-2012, 08:51 AM

Quote:

Originally Posted by Dessertrunner

http://www.ebay.com.au/itm/90-99-SUB...item2318e63bd5

Those tubes look like the kind of tubes used to flow coolant through throttle bodies, etc. Not air. Probably so that the valve warms up to operating temp along with the car and/or doesn't freeze when there's very cold air passing through it.

Dessertrunner · #26 02-07-2012, 12:17 PM

Thanks,
You are right.

Dessertrunner · #27 02-09-2012, 12:50 PM

I have examied the 2 valves, SVX & Liberty it is clear from marks on the SVX valve that it is over closing by about 7mm. The liberty has no such mark. Based on Toms point that the SVX ECU is doing strange things then I need to stop it cutting all air to the engine.
Given this I see a couple of methods to slove the problem so I would like to hear what others think would be the best way.

1 - Milling the opening in the valve so when it goes to fully close the little butterfly is up against the stopper and can't fully close off the air. This will also require the valve adjusted back to return the gap to standard. Can post more detail on how later.
2 - Limit the valves ability to close full by reducting the maxium voltage that can be applied to the closing side of the valve. Don't have the skills to do this with out advise. But maybe put a resister or a adjust voltage regulator on the close wire. (This would be the simplest and least invasive).
3 - Open the butterfly on the throttle to a 600rpm idle (clamp hose to valve when doing it) then remove the valve and adjust it so it almost closed completely. This would then mean that the ECU can do the fine adjustment but can't cut all air to the engine.

Looking at the above options I am not sure what would be best so I open to suggestions. If anyone can jump in with the way to do it electronicly it would be great.
Tony

Dessertrunner · #28 02-10-2012, 02:17 AM

Here is a photo of the baffle when cut from the valve body, you can see the marks showing how far past the close position the valve has closed. When the valve is inthe body it rotates to the left to close.

Tony

Dessertrunner · #29 02-10-2012, 04:06 PM

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.

Tony

oab_au · #30 02-10-2012, 04:24 PM

Quote:

Originally Posted by Dessertrunner

I have examied the 2 valves, SVX & Liberty it is clear from marks on the SVX valve that it is over closing by about 7mm. The liberty has no such mark. Based on Toms point that the SVX ECU is doing strange things then I need to stop it cutting all air to the engine.
Given this I see a couple of methods to slove the problem so I would like to hear what others think would be the best way.

1 - Milling the opening in the valve so when it goes to fully close the little butterfly is up against the stopper and can't fully close off the air. This will also require the valve adjusted back to return the gap to standard. Can post more detail on how later.
2 - Limit the valves ability to close full by reducting the maxium voltage that can be applied to the closing side of the valve. Don't have the skills to do this with out advise. But maybe put a resister or a adjust voltage regulator on the close wire. (This would be the simplest and least invasive).
3 - Open the butterfly on the throttle to a 600rpm idle (clamp hose to valve when doing it) then remove the valve and adjust it so it almost closed completely. This would then mean that the ECU can do the fine adjustment but can't cut all air to the engine.

Looking at the above options I am not sure what would be best so I open to suggestions. If anyone can jump in with the way to do it electronicly it would be great.
Tony

Hi Mate there is no problem to controlling the valve electrically.

You could even remove it from the ECUs control and just have a knob on the dash, but you would loose the auto control that compensates for A/C, Steering, etc, loads.

To alter its effect, to only correct the idle during a particular event, is a bit harder. If the problem is only when the clutch is pushed at low speed, we would have to reduce the 'closing' drive to the unit, only when the clutch is pushed, and have it normal at other times.

This could be a resistor switched in series with the 'close' line by a relay when the clutch switch is closed. Choosing the resistor needs measuring the resistance of the winding to find the current that is run, then working how much more, will reduce the drive, to give the idle speed that you want.

The book says that with the Ignition on, engine off, battery voltage is fed to the center of the two windings, the open drive is 7V, the closing drive is 6V, so the valve would be centred, depending on if there is a spring that powers the valve to a particular position.

All this is based on Toms assertion that the "ECU cuts all air", not doubting Toms recollections but, I think this should be checked out first to see if we are working on the right path. The voltage to the valve should be checked to see what it is doing when the event happens.

Harvey.