IDLE PWM valve configuring

Ludotech · Post by **Ludotech** » Thu May 11, 2006 10:43 am

Hello everybody!

I'm goign to try to start my engine tomorrow so I'm very excited but I'm also afraid!!

I've still a lot of questions: Here is the first (I think that I'm going to read again all the manual this night and post here all the unanswered questions if this doesn't disturb anyone).

so, here is my first question:
In the MS II documentation, it says that:
"to configure the software for the PWM FIdle valves:

* Select the 'PWM Warmup' option for the algorithm under 'Idle Control' in MegaTune.
* Note that the 'Start Value' and 'Time Based Afterstart' parameters in the same dialog do not apply to PWM use (the PWM% is dependent only on the coolant temperature),
So, if I understand correctly, to use my BOSCH PWM valve (it has 3 wires but I'm going to use this circuit to control this valve(I haven't tested this circuit yet), I ignore the "Start value" and "Time Based Afterstart" and only take care of the IDLE PWM DUTYCYCLE under "table"? Am I right?

If someone can confirm, it would help me!

Ludovic

mops · Post by **mops** » Thu May 11, 2006 12:51 pm

I'm running m22, stil code 2.34 (didnt get a change to upload)

I'm using bosh PWM idel valve run by the same circuit as the schematics in your post.

It all runs great.

for me starting value DOES affect the position of the valve... i.e... if I have it open wide on cranking, it wont start, cos it's getting too much air. I set it to about 50% and starting is very good both for cold and hot.

Durning bench testing i confirmed the following:

1. cranking positin is... um... cranking position, duh.
2. after start time is the time it's using cranking settings after the cranking happened (for me 2 to 3 seconds works bets... any more and the engine revs high after cranking, until the valve closes).

any other questions I'm happy to answer.

Ludotech · Post by **Ludotech** » Thu May 11, 2006 1:12 pm

for me starting value DOES affect the position of the valve... i.e... if I have it open wide on cranking, it wont start, cos it's getting too much air. I set it to about 50% and starting is very good both for cold and hot.

I didn't think it was affecting the position of the PWM valve: I though that only the IDLE duty cycle table was affecting the valve. How do you set 50 %? I see that the Start Value (IACStart) is The number of steps applied to retract the IAC pintle to 'wide open' at power up so which value do you enter?

1. cranking positin is... um... cranking position, duh.

What do you mean?

2. after start time is the time it's using cranking settings after the cranking happened (for me 2 to 3 seconds works bets... any more and the engine revs high after cranking, until the valve closes).

Ok, but I see that there are 3 values to enter:

"Cold temperature(Â°C)"
"Cold position(steps)"
"Cold taper time(s)"
So, I don't worry about the cold temperature and cold position but I enter, for example, 3 seconds for the cold taper time?

I don't understand because it talks about steps but the idle valve need PWM...

Thank you for your help!!!!!

[/quote]

mops · Post by **mops** » Thu May 11, 2006 1:20 pm

ok, ok dude.

no stress

1. cranking positin is... um... cranking position, duh.
well... in megatune it's described in number of setps, but when I enter '50' there datalogs will show 50 as the opening value durning cranking, which is 50%

"Cold temperature(Â°C)" - dunno what's that
"Cold position(steps)" - dunno whats that either
"Cold taper time(s)" - this is the time (in seconds) it takes to reansition from cranking powition to collant temp based position.

consider example: ig to cranking value set to 50, engine is hot, so coolant temp value is 85. while cranking it is 50, then for (tapper time) seconds it is 50 and then gradually goes to 85%.

Ludotech · Post by **Ludotech** » Thu May 11, 2006 1:33 pm

Ok, It's clear now!
I'm going to test all that with a scope or with the datalogs when my engine will start(tomorrow I hope!!!).
I made the test and the engine doesn't need the idle valve to start with the OEM ECU so I don't really need the idle valve to start my engine

Thank you again!

mops · Post by **mops** » Thu May 11, 2006 1:38 pm

Ludotech wrote:Ok, It's clear now!
I'm going to test all that with a scope or with the datalogs when my engine will start(tomorrow I hope!!!).
I made the test and the engine doesn't need the idle valve to start with the OEM ECU so I don't really need the idle valve to start my engine

Thank you again!

sounds good....
you dont need valve to start the engine... if you have it on the stationary stand then you can just adjust throttle plate to let in just enough air for it to idle high - but it will work

johnc32779 · Post by **johnc32779** » Thu May 11, 2006 6:07 pm

MOPS, after warm up are you using the 3-wire idle valve to control idle speed? If so, I am puzzled as I can find that ability in MS-II. Conversely, if not, how are you controling idle speed after warmup. The reason I ask is the throttle body on my BMW M30 engine does not have a idle speed adjustment screw.

-------------
BMW M30, MS-II

mops · Post by **mops** » Thu May 11, 2006 6:23 pm

johnc32779 wrote:MOPS, after warm up are you using the 3-wire idle valve to control idle speed? If so, I am puzzled as I can find that ability in MS-II. Conversely, if not, how are you controling idle speed after warmup. The reason I ask is the throttle body on my BMW M30 engine does not have a idle speed adjustment screw.

-------------
BMW M30, MS-II

what are you on about ?

there'a a PWM IAC valve to control it... your car does have one... right ?

if it does then it's most likely 3 wire unit, you will need to build little circuit as in the top post to make it all work nicely. MS2 does have PWM idel valve control option (basically a pwm output via fidle valve)

johnc32779 · Post by **johnc32779** » Thu May 11, 2006 6:40 pm

MOPS, yes it does have a PWM IAC valve, and yes I have added the external FIDLE control circuit for the 3-wire Bosch IAC thanks to your prior help.

But as far as I can determine the MS-II PWM control via FIDLE is for warmup only, and there is no provision for specifying idle RPM.

On the other hand MSnS-E has provision for closed loop control of idle after warmup via PWM FIDLE. See: http://megasquirt.sourceforge.net/extra/pwmidle.html

which includes fast and slow idle RPM parameters.

So, want am I missing? How do I set the idle to say 800 RPM?

mops · Post by **mops** » Thu May 11, 2006 7:02 pm

ah, ok... now i understand.

No, MS2 does NOT have closed loop idle control, like ms'n's/extra

However playing with ignition timing and ve table you can get it pretty close.

for fast (cold idle) just open up the idle valve a bit and adjust warmup settings and it should be all great.

You can define PEW IAC curve, so, eg... i have mine setup so until warmed up the revs hover around 1200rpm and once 85degC is reached the quickly drop to 800...... but you have to tune with with fuel/ignition maps, pwm curve and warmup enrichments.