When out of CL Idle, why is my idle high sometimes?

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tomeric914
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When out of CL Idle, why is my idle high sometimes?

Post by tomeric914 »

Zipped MSL and MSQ attached.

Take a look at the log file starting at the 5080 second mark. Engine was not in CL idle mode, I was decelerating with my foot off the throttle and the IAC valve opened up close to the max duty for some reason that I cannot figure out.

Idle while in closed loop is now very stable. I just can't figure out why it raises the idle at what seems like random times.
tomeric914
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Re: When out of CL Idle, why is my idle high sometimes?

Post by tomeric914 »

Anybody on this one?

I had the car out today and the idle seemed to be working well, stopped to get gas and when I left, the PWM% went up at max duty (roughly 50%) and stayed there even while driving. It wasn't until coming to a stop that I left the clutch in to get the RPMs down that it went into CL idle. From that point on, the PWM% didn't go up to the roughly 50% mark. I can't figure this one out and would appreciate some help!
Matt Cramer
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Re: When out of CL Idle, why is my idle high sometimes?

Post by Matt Cramer »

I see it went to full open when it dropped below the "leave valve closed above" RPM, but I'm not sure why it stayed high.
Matt Cramer -1966 Dodge Dart slant six running on MS3X
tomeric914
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Re: When out of CL Idle, why is my idle high sometimes?

Post by tomeric914 »

Matt Cramer wrote:I see it went to full open when it dropped below the "leave valve closed above" RPM, but I'm not sure why it stayed high.
My thought was that the idle went high and couldn't get back to a point where the conditions could be met for CL idle, but what commanded the valve to full open?

When CL mode conditions are met, the idle valve controls to the target idle setpoint. When not in CL idle, what does MS2 control to?
muythaibxr
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Re: When out of CL Idle, why is my idle high sometimes?

Post by muythaibxr »

You might be hitting a bug that previously was not found due to odd settings or something.

I'll have to take a look when I can get to a computer with TS on it.

Ken
Megasquirt is not for use on pollution controlled vehicles. Any advice I give is for off road use only.
tomeric914
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Re: When out of CL Idle, why is my idle high sometimes?

Post by tomeric914 »

Hey Ken, any luck looking into this?
muythaibxr
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When out of CL Idle, why is my idle high sometimes?

Post by muythaibxr »

No I have not gotten to it, I will look tomorrow evening.
Megasquirt is not for use on pollution controlled vehicles. Any advice I give is for off road use only.
tomeric914
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Re: When out of CL Idle, why is my idle high sometimes?

Post by tomeric914 »

Took the car out again tonight and it is persistent. The datalog is too big to zip and attach, but it is similar to before.

On startup, the car goes right into CL idle and shoots for the target idle RPM which works great.

Start driving and it conditions and after it warms up a little, conditions are no longer good for CL idle and it begins opening the IAC valve to the max duty.

My rpmDOT plot seems rather noisy. I'm currently set at 80 for PID lockout rpmDOT threshold. I'll try 100

This post had a similar event to mine http://www.msextra.com/forums/viewtopic ... 31&t=40169
tomeric914
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Re: When out of CL Idle, why is my idle high sometimes?

Post by tomeric914 »

New MSL attached. Changing the PID lockout rpmDOT threshold to 100 didn't change much. I can't figure out what is causing the RPM to rise and hang.
tomeric914
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If I'm not in Closed Loop idle, what am I in?

Post by tomeric914 »

There appear to be two different modes when running Closed Loop Idle. Closed Loop and Something Else.

What is the correct term for that "Something Else"?

What settings are related to "Closed Loop" and what settings are related to "Something Else"?

This level of detail is not in the manuals, I've already looked.
gslender
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If I'm not in Closed Loop idle, what am I in?

Post by gslender »

There is no something else. You have TPS probably at a value other than zero and CL idle code in the ecu thinks the engine isn't at idle.

If it isn't idling then the engine is running.

G
Mazda MX5 + MS3 Pro
tomeric914
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Re: If I'm not in Closed Loop idle, what am I in?

Post by tomeric914 »

Hmm, ok, I didn't think about it that way.

At a throttle position other than zero, what in the code would drive the IAC valve to the max duty?
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Re: If I'm not in Closed Loop idle, what am I in?

Post by Matt Cramer »

A zero close delay leaves the valve open in those circumstances.
Matt Cramer -1966 Dodge Dart slant six running on MS3X
tomeric914
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Re: If I'm not in Closed Loop idle, what am I in?

Post by tomeric914 »

Matt Cramer wrote:A zero close delay leaves the valve open in those circumstances.
That makes sense, but I don't have a zero close delay.

MSQ and MSL and more details can be found here: http://www.msextra.com/forums/viewtopic ... 01&t=46042
tomeric914
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Re: When out of CL Idle, why is my idle high sometimes?

Post by tomeric914 »

Ken or anyone else, I'd really appreciate some assistance on this one. I've tuned and tweaked and read as much as I can and cannot figure this one out. Thanks.
gslender
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Re: When out of CL Idle, why is my idle high sometimes?

Post by gslender »

There are quite a few things wrong with your tune.

1) Idle open duty is 50.0% - is that correct? when at 50% is the idle valve open such that the "RPM with valve open(rpm)" is really 3000 ?

2) Idle closed duty is 0.0% - is that correct? when at 0% is the idle valve closed such that the "RPM with valve closed(rpm)" is really 850 ?

3) Min Duty for PID(%) is set to 0.0 - is that correct? is this really the floor (lowest) value that the PID controller can instruct the valve to go to ?

4) PID terms are 100, 100 and 1.... I doubt these values would be effective.

It seems as if you've just randomly decided on these values without running the Idle valve test and/or understand their purpose - google all this and read some more.

G
Mazda MX5 + MS3 Pro
muythaibxr
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If I'm not in Closed Loop idle, what am I in?

Post by muythaibxr »

You should not cross post. I am combining your threads.
Megasquirt is not for use on pollution controlled vehicles. Any advice I give is for off road use only.
tomeric914
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Re: When out of CL Idle, why is my idle high sometimes?

Post by tomeric914 »

gslender wrote:There are quite a few things wrong with your tune.

1) Idle open duty is 50.0% - is that correct? when at 50% is the idle valve open such that the "RPM with valve open(rpm)" is really 3000 ?

2) Idle closed duty is 0.0% - is that correct? when at 0% is the idle valve closed such that the "RPM with valve closed(rpm)" is really 850 ?

3) Min Duty for PID(%) is set to 0.0 - is that correct? is this really the floor (lowest) value that the PID controller can instruct the valve to go to ?

4) PID terms are 100, 100 and 1.... I doubt these values would be effective.

It seems as if you've just randomly decided on these values without running the Idle valve test and/or understand their purpose - google all this and read some more.

G
Thank you for taking a look. I did not randomly select values, I did run the idle valve test and have Googled to the point that I cannot find an answer that solves my problem. See my answers below:

1. My understanding was that the "RPM with valve open(rpm)" was the RPM value with the valve commanded 100% open. As I also understand it, the "RPM with valve open(rpm)" is the maximum you want the valve to open. The idle valve test showed roughly 3000 rpm at 100% open, 90% was something less so I knew that 100% must be the max. If the "RPM with valve open(rpm)" should correspond to whatever percentage is input after "RPM with valve open(rpm)", then some clarification for the Googling public needs to be made.

2. 0% is correct. I have my idle bypass valve set to 850 RPM. Many have said to get the car idling in PWM warmup mode first which brings the idle control valve to zero once the engine is warm. That is what I have done.

I have a solid idle at 850 rpm but would like to use the idle valve to drop the idle more slowly so it does not drop too far and stall when clutching in from an RPM of 1600 or above. I am running fuel only so I cannot adjust the timing to catch it.

3. Going back to number 2 above, 0% is idle so as I understand it, that is the floor value PID will command to.

4. I have tried different values in an attempt to keep the idle control valve from going to the max position. I've tried the suggested defaults as well. 100, 100, 1 just happened to be the last iteration. 70, 20 and 0 was what was in previously.

I know that you (Matt, Grant and Ken in particular) don't get paid to read these forums and provide input. We certainly appreciate it. Please understand that we are mostly not as deep into MS as you all are and don't know the subtleties that you know. The manuals do get us most of the way there but are really lacking in details. I've read the manuals and Googled many variations of MS2 high idle, MS2 stuck idle, etc. Some links led to posts that have never been answered. Others led to the user having some other mechanical issue. Ken has hinted that there may be a bug in the code.

I'm trying to figure out why my idle gets stuck at max opening. What combination of value inputs forces the idle valve to full open?

My goal is to have the idle valve to open to a percentage when the throttle closes suddenly to keep the engine from stalling. I'm pretty close, but the random high idle problem is not safe.
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Re: When out of CL Idle, why is my idle high sometimes?

Post by gslender »

The values you are using for open/closed and rpm are probably wrong.

Follow this >> http://www.mx5nutz.com/forum/index.php?showtopic=46823

G
Mazda MX5 + MS3 Pro
gslender
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Re: When out of CL Idle, why is my idle high sometimes?

Post by gslender »

tomeric914 wrote: 1. My understanding was that the "RPM with valve open(rpm)" was the RPM value with the valve commanded 100% open. As I also understand it, the "RPM with valve open(rpm)" is the maximum you want the valve to open. The idle valve test showed roughly 3000 rpm at 100% open, 90% was something less so I knew that 100% must be the max. If the "RPM with valve open(rpm)" should correspond to whatever percentage is input after "RPM with valve open(rpm)", then some clarification for the Googling public needs to be made.
For example, you say 100% but you've set it to 50%, so again I'll ask, at precisely 50% is the idle really precisely 3000rpm ???

Warm up the engine, do the idle valve test and confirm with 100% certainty that the values close/open are the true linear range of the idle valve... such that you can log the test and show that all steps values between close and open are uniformly dropping the rpm from high/open to low/closed (with rpm taking a linear drop down or up as required).

G
Mazda MX5 + MS3 Pro
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