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I have a Bosch idle air control valve which is driven by the PWM  output from the Megasquirt. My Herald has a 1500 engine and ITB.
the problem I have is that the Bosch valve does not close completely so that if when it unpowered it lets too much air thro so I cant get the tick over below 1000  rpm.
There is an adjustment on the valve (Allen headed screw locked with yellow paint) but even playing with this I still get too much air thru the valve when the valve is off. the design of the valve is fairly basic with two rotating metal parts forming the valve, there is no seal on the metal parts so it will still let air thru when its closed. Looking at an old one that I took apart, I think its designed to always let a little air thru, this is a new one but might not be made by Bosch (it was very cheap from Ebay)...

Is there a better (different) idle control valve that closes completely or what do others use?

mike

BTW Happy New Year!

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I gave up with my Bosch pwm type as I just couldn't get it working properly and used a stepper one from a rover 25. You do need the 4 wire stepper control out of your ecu. That one worked straight of the bat and weighs lots less. 

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These are designed for systems where the intent is that there is no other air-path to the engine when the throttle valve is closed, so some airflow will always be needed and tight shut-off not necessary.  Most are designed like this.

Presumably your throttle body does give a tight shut-off and you are confident there are no other air paths in?

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PWM ones need a diode in circuit to work properly.  Darren discovered this last year (or even 2017) and there is a thread on it somewhere.

 

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3 minutes ago, Nick Jones said:

PWM ones need a diode in circuit to work properly.  Darren discovered this last year (or even 2017) and there is a thread on it somewhere.

 

Probably where I went wrong then Nick.

Steve

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1 hour ago, Nick Jones said:

These are designed for systems where the intent is that there is no other air-path to the engine when the throttle valve is closed, so some airflow will always be needed and tight shut-off not necessary.  Most are designed like this.

Presumably your throttle body does give a tight shut-off and you are confident there are no other air paths in?

Nick

I think your are right they are designed to 'leak'.
If I block the air feed to the idle vale then the engine will stall so I am fairly (its a triumph so nothing is completely certain..) certain there are no other leaks.

Chippy63 The valve is working fine, when the car is cold it opens and then gradually closes and reduces the revs as the car warms up. There is a test function in the software that's lets you control the valve directly so you can see what effect it has when it opens.

cheers

mike

 

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Do you know what the OE fitment for the valve is Mike?

The valve for a bigger engine will likely flow more air throughout it's intended range of operation than one intended for a smaller engine.

As regards the air leaks, it's possible that a bit of air does get in elsewhere, which though not enough to allow the engine to idle on it's own, does still add enough to the minimum flow of your valve to raise the idle speed.  You aren't that far above a reasonable idle.....

…… and with that in mind, how much timing do you have in at idle?  Possibly tking some timing out will give the idle speed you want?  Though it may just give a crap idle.

What style of valve is it that you have?  Most of the more user-friendly and conveniently sized ones were from the late 80s /early 90s and are getting hard to find now with more modern stuff being integrated into throttle bodies.

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2 hours ago, Nick Jones said:

Do you know what the OE fitment for the valve is Mike?

The valve for a bigger engine will likely flow more air throughout it's intended range of operation than one intended for a smaller engine.

......

Nick

I think you are correct it was a Bosch used for a 2L VW Passat so a bit large for a 1500 Triumph.
Going to try a different approach and use a solenoid operated air control  valve that closes completely. The control will be a bit more tricky but will worth a try and I have one in the garage to play with. Don't know what they use on Minis need to have a look around a breakers yard. As you say most are integrated into the manifold so more tricky to use. 

cheers

mike

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Hello All

                I use the Bosch type as fitted to Volvo 460 CD ES  93 (well that what it says on the bag)

With no power on it is slightly open as you can see but with power on you can make it shut but it is not air tight(just a curved rotor in a bore)

I bought one as seen on the Right it still is open when no power is on but I thought as it is a valve onto a seating it would be air tight when powered.

It is 2 wire just the same as the Bosch one but when I tried it on the Microsquirt3 in the test mode all it seemed to do was buzz and not work with any setting(only a quick play)

It is a plunger that just goes up and down so I thought PWM would do the same as rotary they are both just working against a spring!

I have a diode fitted in to the harness

I think they are designed to be open with no power as a anti run on with carbs?

So any ideas why it does not work(or is it me?) 

I can not remember what modern car it fits but it was cheap £5 to £6 I think so worth a punt

The Bosch one works well most of the time but every now and then I get a fast tick over (1200/1500 rpm) but if I turn ignition off and on it back to 850 rpm? 

I suspected the valve to be sticking but that's just a guess it could be electronic Gremlins but the system is fine and pretty well tuned now I think( a RR session could get it a bit better but auto tune has done a good job for normal driving range) now I understand it better!

Roger

DSC08336.JPG

DSC08337.JPG

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roger

the right hand one is from a Ford (fiesta or similar), it looks like it should seal completely when off.

I am using the a 'Bosch' clone the same as the left hand one.

Have you tried driving if from the test function and see if its moving properly (look inside at the valve seal)?
I think its the same design as this one in the diagram below. It is or was on my list of valves to try!
But I want to have the valve complelty closed when it off so that I can just use the throttle setting screws to set the tickover.
Glad you have got the tune setup nicely, I think I have gone backwards. I lost the crank bolt holding on the front pulley (didn't realise) and then drove around for a couple of months doing autotune and wondering why the car making some strange noises when it started. The noise was the pulley moving around, not good when all the injection timing is done from the pulley toothed wheel!

Mike

idle_control_solenoid.jpg

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Hi,

 I have at least four ICV's. 2 wire, 3 wire & stepper motor types.

If you need/require TSO, the 3 wire is the one to use. 
From my limited experience in blowing a 2 wire and a 3 wire; The 3 wire was Tight Shut Off & when commanded to full open, flowed more than the two wire.

The 2 wire is easy to DIY control if a minimum flow rate is acceptable. The 3 wire is easier to control than the precision stepper motor types. I have no idea if the stepper motor types can achieve TSO.

Cheers,

Iain.

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Hello Mike

                   Yes it looks like that one.

I had another look at it and I think it works opposite to the Bosch one 

ie  no power wide open and power to close! plus the silver disc on the side is a cover over a small filtered bleed(could be sealed easily)

So now I am thinking was I trying to test it the wrong way or do the connections want swapping over(are solenoid polarity sensitive? must be as it is only a magnetic field!) or I could be wrong but DC motors run both ways depending on current flow! 

When I push it onto the seat is seals completely and it is rubber faced

I will have another play in the next few days

Roger

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Hello All

                Here are the words to Mike's diagram

The older Ford products more often use a spring-load plunger for the idle control valve.  With this valve, the PCM increases duty-cycle to the magnetic coil.  Increased duty-cycle moves the air valve against spring pressure.  When input sensors tell the PCM to increase the engine's idle speed, the valve opens in the IAC, increasing air flow.  The fuel injectors also open a fraction of a second longer, increasing fuel flow.  We increase engine idle speed because additional fuel and air enter the engine.

For instance, switching the air conditioning on, increases the engine load.  With the IAC system, the computer immediately increases the idle speed to compensate.  A cold engine runs with less efficiency and the PCM also commands a higher idle speed.  This helps to circulate engine oil and prevents stalling while the engine warms.  The fuel injectors may also add additional fuel to help the cold engine run better, much as a choke does on older engines.

So does that make me right in my thinking? And can I do this with MicroSquirt3?

More reading of set up needed I think but if it can be done would be more positive (I think?)

Roger

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19 hours ago, rogerguzzi said:

Hello Mike

                   Yes it looks like that one.

I had another look at it and I think it works opposite to the Bosch one 

ie  no power wide open and power to close! plus the silver disc on the side is a cover over a small filtered bleed(could be sealed easily)

So now I am thinking was I trying to test it the wrong way or do the connections want swapping over(are solenoid polarity sensitive? must be as it is only a magnetic field!) or I could be wrong but DC motors run both ways depending on current flow! 

When I push it onto the seat is seals completely and it is rubber faced

I will have another play in the next few days

Roger

Roger

the ford one in the picture should close when unpowered, the spring at the bottom (right hand side of the drawing) should push the seal to block the flow between the input and output. So the setting should Normal 0%=off.

If you have the valve on the bench see if you can blow thru from the inlet to outlet if you can then apply 12v and try again, this will tell you if its NO (normally open) or NC (normally closed). Most valves are described a either NO or NC in the bench unpowered condition.
Trying to recycle car parts is always a bit of a gamble as you never know how it was designed by supplier for a manufacturer.....

I am sure there is a test function to drive idle valve from the software yes its under "CAN-bus/testmodes" > "Output test mode-idle valve". You should be able to move the valve between open and closed.

 

mike

 

 

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Hello Mike

                    Its not quite like the one in the drawing the valve is the other side of the seat so is open, still has the spring at the bottom

Yes there is a test function I have used it many times but as I say this one is opposite to the Bosch one so I was probably testing it wrong?

Will test it in the next few days but have Man flu and banned from the cold garage!

I must admit the Bosch one has been ok but I would like to be able to adjust the bleed from the ECU as I have no bleed screws on the ITB's as the idle valve feeds through these

I could manufacture a manifold with individual bleed screws in each line but that seems a bit OTT?

Roger

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On 1/8/2019 at 7:16 PM, rogerguzzi said:

***

solenoid polarity sensitive?

***

Hi,

two pin solenoids are not. i'm not aware of a diode being built into the solenoid which would make it polarity sensitive.

Cheers,

Iain.

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