NB Idle valve issue - PWM valve running DIYPNP MS2
 

Hey guys,

So I have been running the DIYPNP MS2 on my '00 NB for a while now and things are running well.
I have also got the turbo conversion all finished and a reasonable tune in place (running low boost 9/10 psi).

I thought it was time to finish off all the small stuff and get the car a little more refined but now have run into an issue with the IAC PWM valve. I see a lot of people have trouble tuning closed loop PWM but I am having a problem before even getting this far, its like my valve isn't responding to the ECU.

So I set the ECU to PWM warmup only as some have suggested, but the valve doesn't seem to be doing anything.
I thought the valve might be dead so with the engine running I disconnected the wire to the valve and put 12V across it, you could hear a click as the valve opened and the revs shoot upto 4-5000rpm.
Put a multimeter across one of the pins that usually go into the valve and there is a constant 12V as you would expect.
Put the multimeter across the two pins and get 7.5/8.5V, about what I would expect to see with PWM (unfortunately I don't have a spectrometer to check this 100%).

I found there is a Idle Valve Test so ran this but no changes I make in this do anything at all.
https://www.miataturbo.net/attachmen...ine=1377490499

As a test I enabled the FIDLE in the output settings and the ECU throws out 12V to the valve and revs jump up to 4-5000rpm.
https://www.miataturbo.net/attachmen...ine=1377490499

So now I am a bit confused.
I know the ECU is actually connected to the valve but I cant control it correctly. Has anyone come across something like this?
I'm pretty sure the valve was working fine on the original ECU about 6 months ago.

Is there anyone out there that might be able to shed some light on this?
Ideas?

Cheers,
Dale

you mean it sends a constant ground to the idle valve fully opening it...

the valve runs using a PWM ground. There's constant 12v and the MS rapidly grounds it.


with those fidle output settings, I see no reason it would do anything at idle... you dont have the output trigger until you are over 6K. Plus, there'd be a conflict error unless you disabled idle control completely.

Yep that's what I mean, just typed it a bit odd. I can see the ECU pulls the pin to ground but doesn't seem to be pulsing it (well the valve doesn't react like it is pulsing).

I just used those screenshots to reference the pages where I was trying to test the valve. In the Valve test page I was using figures between 0 and 100. In the FIDLE I actually used coolant as the trigger. (trigger worked great but it nailed the valve fully open as you would expect with that test)

Sorry about that confusion.

I'm also tuning an '00 NB, though not yet turbo'd. I'm using an MSPNP2 and I'm tuning around a set of Deatsch 700cc injectors. Idle is fine, using either PWM warmup or closed loop. I had to tweak several idle control parameters to get there though.

Disregarding the fidle output port setup, how have you set up your idle control? Are you using PWM Warmup? Please post your .msq file so we can have a look.

PWM Warmup is for lazy losers who can't take 2 minutes to set up the idle valve settings and then the next 5-10 minutes to correctly tune the CL PID.

unsure why youre getting no reaction in the idle valve test mode, are you sure you're idle settings page is setup for FIDLE?

I will eventually run PWM closed loop but for now I'll take anything.

At the moment if I try and use PWM warm-up and play around with the settings (and I mean play around with different settings for over an hour) there is 0 response.
I see on the dashboard gauge the Idle PWM % will change to what ever I set it to for that scenario but there is no response from the valve, I have had it up to 60% with no change.

Another strange thing is when I used FIDLE to 100% open the valve even when I turned this back off it stayed open and I had to shutdown the engine and start again. On restart the valve will be closed again.

What are the chances the valve is faulty? It certainly opens and shuts fine but maybe it cant respond to the PWM?

Mine behaved the same way until I reworked the settings. I was pretty frustrated for a while. Please post your .msq file and we might be able to help.

Ok I'll get mine up ASAP (they are on my 'tuning' laptop so cant get it up right now).
What settings did you have to re-work? maybe I can take a look as soon as I get back out to the car (and if I cant get anything to work get my msq up).

Appreciate the help guys, cheers.

My IAC was completely unresponsive with the base tune. The car would fast idle only for the 10 seconds crank-to-run taper duration, then drop to an unreliable slow idle.

The big issue issue for me was the PWM idle valve frequency multiplier. Mine was set to 15 in the base tune the 99-00, which is the max choice in the list box. After a lot of digging in this forum, I found that the multiplier needed to be 16. I had to edit the ini file to get 16, which works a treat.

PWM cranking duty and PWM duty table needed considerable tweaking as well.

Hope this helps!

OK will have a look tomorrow morning and will post back the results with the .msq

I saw the multiplier of 15 and some people were using 16 but the software forced it as a max of 15, I didn't think this would have much of an impact but obviously did for you.

Ok so I wasn't 100% sure what I had changed while trying to get this working so decided I would go back to the base map from DIYAutoTune.
http://www.diyautotune.com/diypnp/ap...00-18bp-mt.zip
I am also running firmware ms2extra_3.2.1

As I didn't have the Req_Fuel 100% right on my first tune I thought this would be a good time to get that closer to what I needed.
The base map had the Req_Fuel at 13 and originally I reduced this down to 7.5 with the new RX8 injectors which I think was a bit off. I am now using 8.5 and it seems much closer to what I want.

Unfortunately the Idle valve issue still remains and is exactly the same as before. All is back to the default idle settings and have tried both PWM warmup and PWM closed loop but still no luck. I also tried changing the valve freq multiplier to 15 with no change. (is this the same that happened with you, but then you went to 16 and got a response?)

Yes. That is correct. I was not able to get any response whatsoever from the IAC valve, other than during the crank-to-run taper at start-up. Once I edited the ini file to set the freq multiplier to 16, all worked fine, and has ever since.

ok I might as well give it a go, nothing else is working!

Do you remember what .ini file you had to modify and how you modified it?

Just looked back over my config and I realized I'd edited my .msq file and not my .ini file. Sorry for any confusion. Open your .msq file with a text editor and search for the following line: <constant digits="0" name="pwmidle_freq">16.0</constant>

You can see where I changed the value to 16.

Hope this helps!

Ok that makes more sense, I was looking everywhere for a .ini file without any luck. I have modified the .msq file and will give it a go.
Cheers for the help, I'll let you know how it goes.

One last thing to change; Valve mode should be "Inverted, 100 % = off"

Give it a try and let us know if it works. Good luck!

it shouldn't be inverted.

Does the inverted/not inverted choice vary among the various MS/MSPNP/TunerStudio/Megatune implementations? or... Did the '99 and '00 models ship with more than one type of IAC valve?

The base tune that came with my MSPNP2 was set to inverted. I experimented with the setting when my IAC initially wasn't working and found it went wide open and stayed there when I set it to normal - like 4k RPM. Inverted, it works as should.

While searching through this forum for answers to my idle problem, I found enough seemingly contradictory information to make it difficult for me to know what was right for my situation. Much of the info came from earlier versions of TunerStudio and Megatune. It was necessary for me to experiment in order to find what actually worked. I'll be curious to see what wydra reports back.

I must say, I'm still very much a newb to the MS and TunerStudio, and I still have a lot of questions that need answering before I'll feel really comfortable with the system, but I'll put those in another thread.

What settings are other '99 and '00 owners using?

Ok so none of this has made any difference to my valve at all.
Freq multipier of 9, 15, 16 and even tried 18.
Inverted and Normal.
I have also bumped the Duty Cycle up to 60%.

The tunerstudio dash is showing the duty cycle changing as it should so I have come to the conclusion it is 1 of two things. Either the ECU is not outputting what I need it to or the valve is faulty.

I have purchased a DigitalMultiMeter that has a Freq/Duty Cycle function so I am going to see what the output of the ECU is.

Does the engine fast-idle for 6 seconds, just as it starts, before dropping? That's what your setup showed in post#11 for crank-to-run time. If it does, then you know your IAC valve operates.

Have you disabled idle control in order to experiment with FIDLE? I see the crank-to-run setting greyed out in post#15. If so, be sure MS is set to operate the IAC normally.

I have removed the ECU from the car and put the original ECU back in to test the valve, it appears to be working fine.

Now I am connected to the DIYPNP MS2 via RS232 and have it on a 12V power supply.

When I measure a 12V source on the board it is reading 12.01V on the DMM. When I measure between the IAC output and 12V I get a reading of 10.61V regardless what I set the frequency and PWM % too in TunerStudio. This is also true for when I try and use the Idle Output Test with any settings.

The only way I have been able to get the IAC voltage to change is if I enable the FIDLE output as shown in this screenshot. Something that I think is strange is when you disable the FIDLE output it stays at 12V until you reset the ECU (the same as what it was doing on the car).

Now the ECU is off the car and I am bench testing is there anyway I can test the IAC operation?
Does anyone know what the IAC point on the sequential injector board is for? (I have not connected anything to it)
Is there something stupid I might have done that I can check for?

Nope there is no fast idle at all, the valve isn't working at any time.

Yes I have set Idle Control to "None" when I enable FIDLE, it acts the same if I have it set to none or if I still have PWM warmup or PWM closedloop selected.

The crank-to-run gets greyed out when you have PWM closed loop selected because the settings is in the 'Closed Loop Idle PID Settings' window.
The crank-to-run is visible when I select PWM warmup (screenshot below)

By your description, it sounds as though it might be a hardware problem. I'm afraid I don't have enough experience yet to be of much help. I hope others will chime in.

It's still possible to have overlooked something in the setup though. If you'll post your .msq file, maybe one of us will see something that needs to be changed.

Yeah I am pretty confident it is something hardware related.
Here is the .msq that I am currently running.

I don't see anything that could account for the lack of IAC control. Maybe others can see something. Meanwhile, how is the hardware testing coming along? Find anything?

Nothing useful unfortunately.

I have found that Pin 20 of the J2 header on the microsquirt module is for FIDLE. This is also giving the 10.61V output, the same that is seen at the IAC pin that goes to the connector board.

Do any MS guys out there know if this behavior is correct?
Does the FIDLE pin out of the ECU connect directly to the IAC pin and works with the PWM valve (with the inclusion of the pull up diode to 12V)?
Is there anything I can be testing to see if the IAC is functioning correctly?

So I have been told the hardware is doing what it should be doing and this is probably Software related.
Great, software should be easier to fix fight?
Can anyway shed any light on what might be going on?

I have upgraded firmware to 3.2.5 with the same results.
Not really sure where to go from here.

When I first installed my DIYPNP I had the same issue except mine was an easy fix. I forgot to install the flyback diode. Is yours installed?

Thanks Hector, I wish it was something like this.
I have the flyback diode installed on R5 (IAC) with the band of the diode going to 12V.

I plugged the ECU back into the car to get a log of it trying to control the valve.
I started up the engine and started to log. The valve remained shut and I needed to add accelerator to keep the revs up just as it did before so I stopped the log.
I then turned FIDLE output to 'ON' and the revs shot straight up to 5-6k rpm just as it did before so I switched the engine off.
Then I powered up the ECU again to turn off the FIDLE off and TunerStudio said there was a config error (obviously for having the FIDLE enabled and Idle control on).
I turned FIDLE off and just left PWM Warmup on.

THEN....

When I restarted the engine, the valve is working!
Went into valve test and the valve is following what percentage I set it to with revs increasing and decreasing as I change the figures.

I'm not really sure what is different to before as I have tried this exact procedure with the older 3.2.1 firmware so maybe it is something to do with the new firmware?

Thanks to everyone that tried to help, all is now well :)

Good work! I'm glad you've found success!
I'm using an MSPNP2, which is similar, but not quite the same as a DIYPNP, but I suspect they both need to be power-cycled for some changes in setup to take effect. I see a banner appear across the top of my TunerStudio stating such when I enable FIDLE or make other related changes.

I experimented PWM CL idle over the last weekend and I had to power-cycle to get the idle back from 5k or so, when I changed FIDLE or inverted the idle PWM. I also upgraded from 3.2.1 to 3.2.5 and I saw no change in behavior between the two revs in that regard.

So, did your idle surge/oscillate?
I'm having this problem right now. Ms2pnp for 99-00 but on my built motor.
My idle test didnt changes anything.
As the car is sitting now if I unplug the iacv the car well keep its idle but oscillates badly. if I keep the valve plugged in it starts,oscillates , and then eventually stalls.

I was trying to get a stable idle and still respond to A/C without hunting. I wasn't successful. I could get a stable idle, or I could respond quickly to A/C, but not both.

The MSPNP2 has a trimpot inside to adjust for A/C idle-up. I'll set it up next time I have it out of the car.

I'm not serious about getting it perfect right now anyway. I'm driving the car NA this summer, and will turbo it this fall. I'll need to retune for the turbo anyway and will work out the little details when I have all my new hardware installed.

Just for some closure on this topic.
I spent a lot of time getting my PID settings tuned and managed to get the idle 90% there. It would never stall while driving and was quick enough to catch the A/C BUT it would oscillate. At the start the oscillations where quite bad but with some tuning of spark and fuel (had to run it reasonably rich) I got it where it would only oscillate a hundred rpm or so.
The only thing that reduced the oscillation was reducing the frequency multiplier. The suggested is 16x and anything under 13x the valve sounded like a plane propeller so I settled with 13x and dealt with the oscillations for a while.
I then bought a JBPerf PWM converter Board,
PWM Converter Board
set it to 16x and 1x on the MS (and inverted the signal) and now my idle is 100%.

Awesome! I Can’t recommend this enough for anyone having issues getting their idle dialled in.
I was even able to lean out the idle A/F to what it should be and it is still rock solid.

I idle off of idle screw. Yay me.

I'm curious as to what you think made it 100%. If I read this correctly you still have the valve at a low frequency 16x. You had it at 13x before so not a drastic change and not really using the function of the board which is to multiply the frequency to one not available in the code.

Which btw, the 3.3.1 code has the capability for much higher frequency. I'm using the 01 TB on my car and running it at 300hz, IIRC. That frequency gets rid of the humming from the valve.

And I don't understand the inverting of the signal?

I'm still nowhere near where I would like to be with my idle but I admit I have not spent any real time tuning it so its my own fault. And part of it may be mechanical issues I am overlooking. But if you think this really did the trick I would be very interested in trying it.

From everything I read the MS multiplier is a software multiplier and as soon as you start using this you lose resolution (a 10x multiplier only gives 1/10 the steps as a 1x multiplier).

The base frequency of the MS is 30.5Hz so when I ran my 13x multiplier I was running the valve at about 400Hz which was as low as I could get without it sounding too loud.

Now with the board I am running a 16x multiplier on the board and 1x on the MS (multiplying the original 30.5Hz to almost 500Hz) but keeping the full resolution.

This resolution is what has stopped the oscillations.

Got it, thanks for the explanation. I don't have acess to TS right now but I'm positive we have the option of going to 500hz in the 3.3.1 firmware without the need of a multiplier. I wonder if it's the same now as what you have accomplished.

Also you never answered on what you meant by inverting th signal?

It goes to 480 Hz. The help text reads:

I run mine at 279 Hz.

- Tom

Tom, IIRC your ECU has the expansion board that already does the hardware multiplication.

If you switch to 1x and the valve doesn't buzz, then you have the hw multiplier and in this case, increasing the software multiplier makes it worse.

Nice, I'll give it a try if I can figure out how to do it. This is how the Idle Control looks in the current version of TS with MS2/Extra v3.3.1:

https://www.miataturbo.net/attachmen...ine=1391463137

The lowest I can set is 31 Hz - would that be the equivalent of a x1 multiplier?

Cheers,
- Tom

Correct.

OK so if I understand correctly, the new firmware (3.3.1) doesnt really do anything different from the old firmware (3.2.5), they just changed the terms and gave you frequencies up to 480hz which is the equivalent of a 16x multiplier? So using ~300hz you have about a 10x multiplier and have lost resolution. If 156hz the valve works at 2% steps then it works at 4% steps a 300hz, correct?

Rev, is this why you put in the expansion board or is that spec'd out individually on your MS2/Extra builds?

Hector, the inversion is required as when you add the expension board it inverts the output. This change can simply be done in the software.

I'm not sure what other versions of MS have what hardware.
I am running a DIYPNP2.
DIYPNP MegaSquirt installation for the Mazda Miata

Originally I started with Firmware 3.2.1 and then moved over to 3.2.5 (can anyone say it is worth while going over to 3.3.1?)

Using TunerStudio 2.5.05

Mine don't look like that D: I must need to update. Our is my ms2pnp.

Did setting your mspnp2 to pwm closed loop fix your high idle issue? I have the same issue with my mspnp2. I'm running firmware 3.3.0. As soon as my car starts it idles at 2k + even with the idle screw all the way closed.

Im not sure who you are referring to but the OP resolved the issue in post #30 in this thread. It was a "phantom" fix. Also, he has a DIYPNP and not MSPNP2. They are MS2 based but not exactly alike.

BTW, DIYAutotune has fantastic support.

Im experiencing the exact same problem with the same settings as above. I tried disconnecting the iac, but shoud it return to closed by itself? It revs to about 3k all the time with or without the iac connected.

Blinded the IAC. Problem gone. It was stuck halfway open...