Trial for five speed stall.

[Dessertrunner]

I have a suggestion and need one of you guys thats car is currently stalling to try something. The idle control value under the throttle body may be the reason we are stalling. I will explain, it is controlled by two transistors in the ECU. When an adjustment is needed to increase the idle the ECU reduces the voltage on one and increases it on the other, in that way it rotates the valve to adjust the air. When my car was idleing two high I unplug the unit while still on the throttle body (with great difficulity) and pluged a spare unit in so I know the next step I am going to suggest is possiable.
What I suggest happens is that when the car stalls its because one transistor is shut down completly and it causes the valve to cut the air totally at which time the MAF etc read that the engine is not running and shut down the fuel and spark.
What I need one of you guys to do is remove the plug from you idle control valve (use long nose pliers) and either put up with the error code, the car will still run and won't give you any problem or you can plug in a spare to stop the error code. Next go for a drive and see if it still stalls as it did before.
I will bet it won't stall any more.
Tony

[Dessertrunner]

I have given this more thought and I am trying to work out a way to control the idle from inside the car. So I have made up a double Pot so as I can change the voltage from one wire leg to the other on the valve. It has three wires , Common, High idle and pull low. With the pot i should be able to shift between the two by moving the biases of voltage. All so I have attached a photo of the valve involved.
Tony

[Dessertrunner]

Okay I am on the job and working by torch this is the plug I want off with out taking the throttle body off. And here is the photo of it off.
What I posted in the earlier posts is wrong the method of working is different to what I thought.
Centre wire is common, White is Up idle, Black wire is lower idle but what I didn't realize was that don't work at the same time. The ECU adjusts the white wire voltage to advance the idle, nothing smart about that. The black wire is turned on only when the ECU wants to breaK the engine.
Now I have to figure how to get the spare valve into the cabin to watch what it does and when it decides the shut down. Tom said he beleived the engine was break when we got a stall and I think he was right.
Will follow when I discover more.
Tony

[Trevor]

Tony,

I don’t think you have the correct picture regarding the operation of the BY-Pass Air Control Solenoid Valve (BPACSV). However I hasten to add that as I have not had the opportunity to examine a specimen, I must make assumptions in some respects, based on what information is available.

After the engine reaches normal temperature, The Auxiliary Air Control Valve closes, and the BPACSV becomes the sole idle controlling device. Control via the ECU, is such that engine RPM is maintained at a constant specific level, regardless of parasitic engine loads, therefore this requires that an engine speed signal is involved.

In order to maintain steady idling speed in spite of a variable load, the ABPSV must be in effect comprise an air metering device with a variable opening. The manuals illustrate a single solenoid coil with two windings. A shielded wire is shown labelled “open”, and an unshielded wire labelled “close”. Two associated transistors a shown in an unlikely configuration. One can only assume that the diagram is intended to be nothing more than a figurative illustration, of a more complex system.

I would expect that what we have is basically a pulse width modulated solenoid proportional valve, a control signal line to the operative solenoid winding, and a feedback circuit from a secondary winding. I could be wrong in respect of detail, however on/off or variable voltage control as suggested, is not feasible.

N.B. All that said, the important point is that left as is and as designed, the BPACSV should control idle regardless of the transmission involved. There is no reason why this part of the idling air circuit, should be regarded as problematic provided that it has not be impaired or altered in some way. Furthermore modification of same is not a logical way to correct an induced problem.

Unfortunately this issue is now spread between several threads to the extent that Keeping track has become extremely arduous, whereby it is becoming difficult to maintain interest.

In any event Tony, be sure that I am not putting you down and investigative experiments are an important way to gain knowledge. (Here with difficulty I am trying to pass a compliment, without inferring any form of patriotism, which I loath. )

Sincerely, Trevor.

[Dessertrunner]

Trevor the manual list the pins involved with the Open & Close of the BPACSV as being variable voltage. Lab tests on my spare value have confirmed that by varing the voltage the value opens and closes. As you would be aware the valve has an "At rest Open position" that every one has adjusted to get round the problem and it has not worked. What untill today I was unaware is that it opens from the at rest position and Closes from that position. On a lab test it is possiable to control the rate of opening by increasing the voltage on only the open wire, take the voltage away and it goes back to the at rest position.
What I have now learnt from tonights trials:-
I discontected the the value and left the plug lose. went for a drive once the car was hot it ran okay, still stalled and at idle ran rough. Check Engine light was on permently. At this stage I beleived I had got it wrong.
Next I pluged in the spare BPACSV into the plug and tucked it in at the side of the engine. Once the engine acheived temp the car ran perfectly I proceeded to drive it round town for about 1 hour to see if it would stall. I forced the engine to go as low as 250rpm and it did not stall. Not once did the engine stall at all. In fact the engine was more respondsive to the throttle by that I mean when I lift my foot the engine did as it was told for once.

If we take on board what I say as possiably being correct and the valve is controled by voltage not modulation then the transister circut makes sense (they amplifie voltage).
Sorry about the different thread but it was dealing with a totally different aspect of the issue also its easier some time to just start a new thread that get told we are off topic and should find a new thread.
Trevor I am happy to run any test you suggest to see if what I say is correct and hope fully some one else will try this out so we can compare results. If you think about it if this valve only controled idle they would have called it the "Idle control valve", they didn't because its used to break the engine as Tom suggest that some thing was.
I now need you help to figure out how to con the ECU that the black wire is still connected.
Tony

[Dessertrunner]

For those that may be interested this is what I did I made up a harness and put my spare valve in the car so as I could watch how it behaved. When ever you put your foot on the accelartor the valve opened part way. When you lift your foot off the majority of times the valve was slow to go back to the idle position. On certian break and slowing down the unit closed off completely.
I then disconnected the wire that closed the valve and put in a resister of the same resistance to con the ECU. It didn't work the ECU was smarter then I gave it credit for.
Driving the car was possible and good as long as I had the spare Valve pluged in.

Were to now, I would prefer to run with out the BPACSV (Value) operating on the close cycle but could not find out how to do it. At this stage I am joining in on Team to crack the ECU code and try that way.
Have a great day I am going testing my new tyres in the dessert for 5 days.

[black beast]

mine was staling too, but then I tuned the idel so that is was higher, and the stage two chip helped map what the fuel should do when it shifts...

[Dessertrunner]

Thanks I might give stage two a try in mine.

[Nomake Wan]

Welcome on board!

If we find the code for this, or if you do, then I'm sure we'll post it up. People with five-speeds can then burn themselves a chip which will solve the problem.

I'm sure there are many people who are trying to find a solution for this problem. It looks like you've found the real source of the problem, so now it's just a matter of time...

[Trevor]

Originally Posted by Dessertrunner

For those that may be interested this is what I did I made up a harness and put my spare valve in the car so as I could watch how it behaved. When ever you put your foot on the accelartor the valve opened part way. When you lift your foot off the majority of times the valve was slow to go back to the idle position. On certian break and slowing down the unit closed off completely.
I then disconnected the wire that closed the valve and put in a resister of the same resistance to con the ECU. It didn't work the ECU was smarter then I gave it credit for.
Driving the car was possible and good as long as I had the spare Valve pluged in.

Were to now, I would prefer to run with out the BPACSV (Value) operating on the close cycle but could not find out how to do it. At this stage I am joining in on Team to crack the ECU code and try that way.
Have a great day I am going testing my new tyres in the dessert for 5 days.

Tony,

You say, “On a lab test it is possible to control the rate of opening by increasing the voltage on only the open wire, take the voltage away and it goes back to the at rest position". Note that a valve designed for pulse modulation, will respond to a constant voltage in this sort of way.

You refer to “rate of opening.” Are you saying that the amount, degree, area of opening is directly proportional to the applied voltage, and that it can be held part open after the rest position, because there is some form of friction device which will retain the position of the valve?

Or is it that with sufficient voltage applied the valve moves to the fully open position and closes to an idle position when the voltage is removed?

Your testing has not explained what happens when the second wire is energised. I have not had the opportunity to examine a specimen, and have no details regarding an idle position and completely closed position. Is this the reason for the second wire by any chance, so that what we have is, a two position valve, with closed, intermediate and full open positions.

You also say, “If you think about it if this valve only controlled idle they would have called it the "Idle control valve."
The manuals I have specifically refers to the valve as, the “BY-Pass Air Control Solenoid Valve”, and the second valve as, the “Auxiliary Air Control Valve.”

As I perviously explained, there are two valves involved in controlling the idle. ----- After the engine reaches normal temperature, The Auxiliary Air Control Valve closes, and the BPACSV becomes the sole idle controlling device. Control via the ECU, is such that engine RPM is maintained at a constant specific level, regardless of parasitic engine loads, therefore this requires that an engine speed signal is involved.

Substituting the solenoid with resistor will have no effect regarding the ECU, because an output control voltage is involved and not an input signal.

As a means of fixing the problem this angle remains very much alive pending answers as called for above.

[Dessertrunner]

Trevor,
you need to cut me a bit of slack as I am terriable at explaining things also early in the morning I will be pull out for the desert for 4 days so won't be checking the forum.
On the test bench I found that the centre wire is the Postive and goes to the main engine power circut. The white striped other wire is the one that opens the valve as you increase the voltage. The black wire closes the valve as you increase voltage. No power or less then 6V means the valve stays at rest. What I may have missed explaining is the at rest position is spring loaded in both close & open.
The bench test was done by appling the centre wire to the positive and connect the neg to one of the other, using a Lab variable power supply as the voltage was increased the power in the electro mangenet would over take the spring force. This observation applied to both Open & Close wires, vary voltage portational open or close valve depending on which wire.
From the expermenting I did I have no doubt that when we can control this little sucker from reprograming the ECU we will all jump with joy. When I had it in the cab it totaling cut the air on a number of occusions and if the ECU was stuffing around with either fuel or timing at the same time you can easy see why the engine would die. What I also noticed was that the car would move away from a standing stop a lot easier then when the valve disconnect from being under ECU control. Seems that with a maunel gearbox you need to feather the throttle and clutch before fully letting out the clutch.
One thing for sure control this valve the engine is a far better beast. My reson for that statement is that under hard driving and on and off the fuel its as important to get the power off at the right time as on. If the power comes off fast you can tuck the nose into a corner then at the rignt time power out currently my SVX hasn't got a hope of doing that. You should try it with your car in netural rev it up quickly then lift your foot and watch how long it take to go back to its orignal ideal. With the valve disconnect and dummy in its place the responce is imendient. Sorry to give such a long winded answer but I hope I explained it right this time.
Have a great day or night peoples I am going to the dessert test track to have me some fun, 5,000 in 4 day.

[JaySVX]

I think young tom figured something out for the 5mt stall, he offered to fix mine for me last time i was out there, but the frequency of my stall is low, so i passed. Perhaps he'll see this and check in with what he knows.

[Trevor]

Tony,

Apologies as I have overlooked your post, but note that you have been away so perhaps no harm is involved.

You say, ”The bench test was done by appling the centre wire to the positive and connect the neg to one of the other, using a Lab variable power supply as the voltage was increased the power in the electro mangenet would over take the spring force. This observation applied to both Open & Close wires, vary voltage portational open or close valve depending on which wire.”

I can not see how the valve can be held partly open or closed by applying a constant voltage. You may have observed a slow or variable degree of speed in opening and closing, but holding the valve fixed at an intermediate position, is an entirely different requirement.

My assessment based on your testing and the fact that the "open" circuit is shielded, is that the valve is controlled so as to be stationery in, (1) a closed position, (2) an intermediate open position and (3) varying degrees towards fully open. The latter (3) by means ot a modulated signal.

This arrangement would provide for ---- (1) Economy when on over run and a shut throttle. Also possibly to prevent running on at shut down. (2) A normal idle position. (3) Control in order to adjust idle speed against parasitic engine loads.

I know exactly where you are coming from in respect of the nicety of an engine which drops revs instantly when the throttle is closed. I have this issue with my Mazda Miata. In this regard it would appear that all is well as long a the valve is disconnected and therefore is in position (2).

It would appear to me that disconnecting the "close" circuit, could very well fix the problem. This is a must as an experiment, i.e. to disconnect what you advise is the black wire. You can do this without damaging your wiring, by removing the connector from the plug, by inserting a small screw driver to release the small tab which holds the connector in place.

Your earlier posts indicate that a dummy load across the "close" circuit may be required to satisfy the ECU and your spare valve could provide this on an experimental basis. You mentioned making up an extension harness and I doubt that this included a shielded wire, so that this may have been a factor upsetting earlier test results. In which case the dummy load may not be required.

Try first with the "close" circuit disconnected, then if necessary add a load, i.e. as two independent tests so that you know exactly which is affective. Whatever you do, do not extend anything other than the black "shut" circuit. An open unshielded line, or earth/ground loop, could upset things and contradict any experiment.

As I see it, this mod. would retain the ECU ability to adjust for parasitic loading, but would prevent the unwanted shut off signal. With so little inside information, it is a matter cut and try, based on reasonable logic. Give it a try and report back.

Please appreciate that I have analysed from a distance and I may be astray. If what I have suggested does not work, the next step will involve a look at the two signals, using a scope and if I feel energetic, I may assist.

[TomsSVX]

you might be onto something here. By removing the wire there may be a cause for a CEL though.

Tom

[Trevor]

Originally Posted by TomsSVX

you might be onto something here. By removing the wire there may be a cause for a CEL though.

Tom

Not a problem. A substituted resistance, or if the system is extremely high tech. an inductance, will prevent a fault signal.