Chowcow

I've read into my issue about low RPM warmup idle and idle dip for quite some time now and haven't been able to figure it out. However, I'm starting to understand the closed loop PID settings a bit more and have followed numerous guides to how to find your min/max duty %.

Following Braineak's guide, I did the following to identify my duty % -- but my numbers are VERY off.

1) Test valve setting. Set it to 0. When warm, the car idles at 750RPM at this setting.
2) Raise test valve setting to a number that begins to affect the RPM, this number is 75%.
3) Raise test valve setting to a number that no longer raises the RPM, this mumber is 100% for me.
4) I've read that 90-93s run around 23-64%.

So if these values ring true, I should be setting my minimum to 75 and max to 100%. But again, these values seem crazy high.

What's going on here?

2003 NB Miata (RX8 injectors, CAI, mostly stock otherwise) , MS3 Rev built.

curly

iTrader: (25)

These are the same numbers for Lazarus, we're 100% sure something is wrong with the valve.

Chowcow

Any link to his thread? What did he do to fix it? My idle is fine with my original ECU, although I'm not sure how that translates to the MS3

curly

iTrader: (25)

So far we haven't done anything, our first step will be cleaning it it, after that GreddyGalant has a new valve to install, after that we'll look at our wiring. We're leaving wiring for last because it does work, just in a different range than it should. It also feels like it's sticking. So I'm suspecting a blockage, either of oil, carbon, or gasket. Followed by a slightly sticky valve.

Greatest build thread in history:

https://www.miataturbo.net/build-thr...nothing-75005/

Surprised it's not bookmarked yet bro...

18psi

iTrader: (76)

yeah I'm at like 6/28 iirc

curly

iTrader: (25)

28% max? How's it start? Even with properly working ones, I'm around 50% for cold starts.

18psi

iTrader: (76)

cold start idle valve settings are 36-46 iirc
I'll have to double check all this on my laptop, but pretty sure that's the ballpark

curly

iTrader: (25)

I know you're not at your laptop, but I'm pretty sure the closed loop idle valve min/max goes for cranking duty too.

And I just found Laz's problem, his settings were set to inverted, where 100%=closed. Oops.

deezums

iTrader: (3)

Not on my setup. I can call for all the idle valve on start, but it won't ever naturally go higher than the limit after the afterstart taper has run out.

Something I do to tune vapor lock injectors on hot restarts, or at least in theory. I can have high RPM starts with plenty of valve, but it won't ever rev like mad at a stoplight again and get stuck outside closed loop entry conditions.

aidandj

iTrader: (5)

For funsies I tested my valve at 100% the other day. Something like 4000 rpm. Racecar idle.

Chowcow

So now that I've tested my car at 75% min and 100% max, is there a reason why I wouldn't enter those as my min/max duty in CL idle?

The logic being that the valve isn't actually opened 75% at min or 100% at max (because all the problems listed above), so it would be equivalent of me setting it to what everyone else has at 23-65%ish. Does that make sense to anyone?

As of now, my idle open duty during cold starts is 80%, which allows me to start the car without throttle. I just need to dump in a ton of gas for ASE/WUE to keep it rich during warmup. However, it prevents my car from stalling when I drive around when the engine is cold. Any reasons why I wouldn't set my parameters like this?

NiklasFalk

iTrader: (1)

Remember that it's % duty cycle (PWM), not % open.
If you can get decent function, use the values that works for your case.

BTW I had about 5.2krpm at fully open NB valve when I used a flattop, not a quiet test in an apartment garage...

Chowcow

Thanks for that, I wasn't aware of that.

So I took apart my MS3 and measured the diode and found that I get 0.6V when measured the proper way (negative to negative) but 2.5v when measured the other way around. However, I just realized you're supposed to do these readings when the diode is off the board, as these readings may be from something else. So I'm not sure how valid these settings are anymore. I was hoping I would get no reading on my flyback diode as this has been the problem for most people on these boards.

My second question would be about my CL idle. Now that my PWM duty % is set so high (70min// 85 max), do my CL idle PID settings also have to be extremely high? I noticed that when I drop all my PID terms out (all 0), my idle remains the same at 850RPM and idles very nicely- it also returns to the idle after throttle inputs too. So this tells me my PID isn't working? Or do I need to set them in the 100s to get any effect out of it?

I know I'm entering my CL idle as the indicator tells me so. So what's the deal with my PID settings? The only reason I'd like to fix them is that after I throw the clutch in from driving (when cold) the RPMs plummet to near stall conditions, raising the max PWM duty to 85% has stopped it from flat out stalling every time.

Also, the TS reads that my PWM duty is at its max when warmed up, so its always at 85% and never moves from there. I'm not sure if that's proper as I think the PWM value should change when the car is warmed up.

Braineack

iTrader: (62)

if you're showing the CL ON light, but you're pegged at 85%, that would assume that you're not able to reach your CL target.

75-85% duty cycle range is wrong.

all 90-97 valves operate between 20-60%DC. the NB valves usually run between 60-100%DC.


our idle valves need a diode to 12v, if youre hardware doesn't account for this (ms3pro, or what seems to be the ms labs ms3 basic) you need to wire it in.

Chowcow

Thanks for the input Braineack. I'm sure everything was wired properly, i'm running an MS3 by Rev. What I'm not sure about is whether that Diode is working properly, or another component (identified by Rev -AUIRLZ44- ) might be defective. I checked the Diode and got a 0.6v reading when connecting it neg to neg, but then a 2.5v when pos to neg. But then again, I read that you can't get a reading from a diode when its on a board.

Here's my question, so if I set my PWM min to 60 and PWM max to 100 (although 75 is around what my min appears to be when I valve test). How do I know when I'm able to achieve my CL target? What % PWM duty should I be looking for when I'm idling with the CL light on?

My RPMs are more or less around 850- what I set them to. But I don't think CL is doing anything to get it there.

Reverant

iTrader: (10)

Warm idle values for this valve should be in the 30-40% range. Maybe in the low 30s if the bypass screw is all the way in. At 50% you should have more than 2000rpm.

curly

iTrader: (25)

So what does it mean to be idling around 75%? That's what Laz does with his MSPNP2, two other MSPNP2s, one on a 94, one on a 99, both idle at a more respectable 25-35%. It's now done this with two valves, should I be looking at my wiring?

Braineack

iTrader: (62)

I'd expect any 90-97 to idle in the 25-35% idle DC range.

if your valve is operating at 75% you either have the idle speed screw fully open, or the diode to 12v is failed/bad.

Chowcow

How do you suggest I adjust the idle screw? Should I shut turn it off fully (clockwise) then experiment with the PWM idle values? Or should I be backing it off until I hit that 25-35% warm range?

Thanks for the input.

NiklasFalk

iTrader: (1)

The idle screw is not the issue, but open it (with the idle valve closed or disconnected) until warm idle is raised a little (eg 800).
It's two parallel air channels so you are only moving the balanced valve position slightly.