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

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

Postby tomeric914 » Sun Aug 05, 2012 4:44 pm

gslender wrote: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 ???

Thanks for the idle valve test link. I had found that previously and used it. The key to the idle valve test is to enter the value and press the "Enter" key and not the "Burn" button

I just went out and did the idle valve test again, twice to verify each one. Here are all of the values so there is no confusion. Values were taken from the RPM gauge in TunerStudio.

100% - 3000
90% - 2850
80% - 2750
70% - 2625
60% - 2450
50% - 2300
40% - 2000
30% - 1450
20% - 1250
10% - 1000
0% - 850

You may be looking at the first MSQ that was posted on this thread. My most recent MSQ has the RPM with valve open set at 2000 rpm and it still has the RPM hang issue. Does the code look at that "RPM with valve open(rpm)" and if it can't hit that RPM, does it get stuck? That's probably not the case because it was set to 3000 and it still got stuck.

I attached the most recent MSQ for clarity.
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Re: When out of CL Idle, why is my idle high sometimes?

Postby gslender » Sun Aug 05, 2012 5:59 pm

Ok, using the msq you've provided here, can you please do some logs and outline where specifically in the log the issues presents. Also include a log with a clear period where it is idling. Also ensure the engine is fully warm when doing this. Would be best not to confuse with engine warming issues.

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

Postby tomeric914 » Sun Aug 05, 2012 7:11 pm

gslender wrote:Would be best not to confuse with engine warming issues.

I get a solid CL Idle when cold and when fully warm. It's that middle ground where the RPM hang usually happens. I'll get a log tomorrow. Thanks again Grant.
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Re: When out of CL Idle, why is my idle high sometimes?

Postby tomeric914 » Mon Aug 06, 2012 6:26 am

MSL attached. BTW, this is an aircooled flat 6 so the coolant temperature reading is actually my oil temperature.

It starts to hang at 44926 seconds. I can force the RPM down by applying the brake with the clutch engaged. That gets it into CL Idle.
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Re: When out of CL Idle, why is my idle high sometimes?

Postby gslender » Mon Aug 06, 2012 7:25 pm

tomeric914 wrote:MSL attached. BTW, this is an aircooled flat 6 so the coolant temperature reading is actually my oil temperature.

It starts to hang at 44926 seconds. I can force the RPM down by applying the brake with the clutch engaged. That gets it into CL Idle.


Make only these changes and reproduce a log for me.

1) Change the Idle Open Duty to 30%, and the RPM with valve open(rpm) to 1450 - by restricting the valve movement to just enough to help with idle, it won't be able to command 50% idle valve and push the rpm so high it can't be detected as being at idle. You really want the idle valve to have a small effect to control minor load on the engine (like fans, pwr steering etc), not enough air to allow the engine to hit 3000 rpm.

2) Change Idle Activation RPM adder (rpm) under Closed Loop Idle Valve Settings, to a value of 500 (this needs to be high enough to ensure CL idle is entered) as in most cases you are off throttle and RPM is sitting way too high for CL idle to enter.

3) Change Idle Activation TPS threshold (%) under Closed Loop Idle Valve Settings, to 1% to ensure there is no small TPS fluctuations causes by TPS noise stopping CL Idle from entering.

I'll look again once a new log exists.

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

Postby tomeric914 » Mon Aug 06, 2012 8:11 pm

Thanks Grant. I will make those changes and post a log as soon as I can.

On #1, if the valve opening is limited to 30%, cold starts may be a problem if the engine doesn't get enough air. I'll give it a go.

I agree on #2, but 500 seemed too high based on what I had read. Help me out with the "idle Activation RPM Adder". From the manual, "if your idle target is 900RPM and Idle Activation Adder is 200 then closed loop will begin when the engine speed gets to 900+200=1100RPM". Should the "Leave valve closed above (rpm)" value be equal to the "idle Activation RPM Adder" plus the "Closed Loop Idle Target RPM"? Otherwise, what would the valve do if it wasn't in CL idle? Seems to me that it would do as it is told. It can't be closed, so it has to open to something which would be maximum. This could explain why I can force it into CL idle by applying the brakes to drive the RPM down.
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Re: When out of CL Idle, why is my idle high sometimes?

Postby gslender » Mon Aug 06, 2012 8:24 pm

tomeric914 wrote:Thanks Grant. I will make those changes and post a log as soon as I can.

On #1, if the valve opening is limited to 30%, cold starts may be a problem if the engine doesn't get enough air. I'll give it a go.


Really? Your engine can't start and idle at 1450rpm? Not many oem engines idle that high when cold - if warm idle is around 800rpm, then cold would be around 1000, maybe 1100 max... but unlikely to be as high as 1450.... but agree that if you need to get that much air into the car then perhaps you are right. Also be certain that you don't have another CLT controlled fast idle... many cars do and have a idle air valve that is mechancially controlled by coolant that allow for more air (leaving the idle valve to focus on the load issues and less on the cold engine air requirements).


tomeric914 wrote: I agree on #2, but 500 seemed too high based on what I had read. Help me out with the "idle Activation RPM Adder". From the manual, "if your idle target is 900RPM and Idle Activation Adder is 200 then closed loop will begin when the engine speed gets to 900+200=1100RPM". Should the "Leave valve closed above (rpm)" value be equal to the "idle Activation RPM Adder" plus the "Closed Loop Idle Target RPM"? Otherwise, what would the valve do if it wasn't in CL idle? Seems to me that it would do as it is told. It can't be closed, so it has to open to something which would be maximum. This could explain why I can force it into CL idle by applying the brakes to drive the RPM down.


Essentially the "idle Activation RPM Adder" is the RPM by which CL idle can be allowed to enter... so the code doesn't even enter CL idle (seen in the log as Status2 being at 128 if in, 0 if out of CL). In your logs, in most cases the status 2 isn't 128 which means the CL idle code isn't even trying to control the idle valve and is probably stuck in some in-between state of being off idle and returning the idle valve to last-known-good position which might actually be 50% (which as mentioned before, is too big a value to idle from).

Overall, I think 3000rpm for 50% is probably the main problem. Get the idle valve limited to controlling a sensible RPM range and it might all start working better.

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

Postby tomeric914 » Mon Aug 06, 2012 8:32 pm

I am positive there is no other CLT idle valve, but the car does need a lot of air and fuel to get started. I'll give it a try and see what happens. Going down now to burn changes. Log tomorrow. Thanks again!

EDIT: I just noticed that PWM Cranking Duty % overrides the Idle Open Valve % so there should be no problem getting it started.
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Re: When out of CL Idle, why is my idle high sometimes?

Postby tomeric914 » Tue Aug 07, 2012 5:33 am

MSL attached reflecting Grant's changes only.

Certainly better with the valve limited to 30%. 1450 rpm is a lot less embarrassing than 2100 rpm

Why was the valve commanded open to 30.1% when the RPM was above the "Leave Valve Closed Above" setting of 1600 rpm? The first instance was at 1317 sec and 2300 rpm while decelerating. The second was again while decelerating at 1438 sec and 1750 rpm. Both instances resulted in the idle valve being left open at 30.1% until throttle was applied or the RPM was forced low enough (driveline engaged and brake applied) to go into CL idle.
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Re: When out of CL Idle, why is my idle high sometimes?

Postby gslender » Tue Aug 07, 2012 10:36 pm

tomeric914 wrote:MSL attached reflecting Grant's changes only.

Certainly better with the valve limited to 30%. 1450 rpm is a lot less embarrassing than 2100 rpm

Why was the valve commanded open to 30.1% when the RPM was above the "Leave Valve Closed Above" setting of 1600 rpm? The first instance was at 1317 sec and 2300 rpm while decelerating. The second was again while decelerating at 1438 sec and 1750 rpm. Both instances resulted in the idle valve being left open at 30.1% until throttle was applied or the RPM was forced low enough (driveline engaged and brake applied) to go into CL idle.


I am puzzled by the behaviour and not entirely sure why this is happening.

For example, at 1112 seconds the throttle is at 0% and the RPM should be dropping even though the idle valve is open (at 30%). Instead it take 17 seconds (a really long time) for the engine to fall from 2250rpm to 1502 rpm.... from which time the CL Idle activates (status2 goes to 128) and then the idle valve is closed to bring the idle back down.

The fundamental issue you are facing is that CL Idle isn't engaging as the RPM are staying high. I guess you'll say that's because the idle valve is open at 30%, but even so, why doesn't the RPM drop (reasonably quickly) to what you are saying is the RPM from the idle valve test? It seems to gracefully fall as if you have some massive flywheel that has tremendous inertia to keep spining way more than normal.

The code is probably stalling at throttle lifted waiting for the RPMs to drop below the "Idle Activation RPM adder (rpm)"condition to activate the CL Idle code and command the idle valve duty to go lower.

I'm unsure what it is sitting at 30% - would you humour me with another change and log. Can you set the lower idle valve setting to 4% for close duty and make the Min Duty for PID% to be 5%.

I'd be keen to see what a log looks like with the values set like that.

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

Postby Mhm » Tue Aug 07, 2012 11:45 pm

Could it begin that the engine vaccum at idle sucks some valve/butterfly open with everything close, causing the high idle and slow gracefull falliese in rpm.

I've had a similar problem before on a carbed car.
Just putting it out there.

You'll have to make sure you can properly control idling with the valve manually in all situations before you can attempt to control it automatically.
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Re: When out of CL Idle, why is my idle high sometimes?

Postby tomeric914 » Wed Aug 08, 2012 6:14 am

gslender wrote:For example, at 1112 seconds the throttle is at 0% and the RPM should be dropping even though the idle valve is open (at 30%). Instead it take 17 seconds (a really long time) for the engine to fall from 2250rpm to 1502 rpm.... from which time the CL Idle activates (status2 goes to 128) and then the idle valve is closed to bring the idle back down.

The fundamental issue you are facing is that CL Idle isn't engaging as the RPM are staying high. I guess you'll say that's because the idle valve is open at 30%, but even so, why doesn't the RPM drop (reasonably quickly) to what you are saying is the RPM from the idle valve test? It seems to gracefully fall as if you have some massive flywheel that has tremendous inertia to keep spining way more than normal.


At 1112 seconds, I was decelerating down a very long exit ramp which is why the RPMs didn't drop with the throttle closed.

gslender wrote:The code is probably stalling at throttle lifted waiting for the RPMs to drop below the "Idle Activation RPM adder (rpm)"condition to activate the CL Idle code and command the idle valve duty to go lower.

I'm unsure what it is sitting at 30% - would you humour me with another change and log. Can you set the lower idle valve setting to 4% for close duty and make the Min Duty for PID% to be 5%.

I'd be keen to see what a log looks like with the values set like that.


I'll gladly make those changes and post a log later tonight. Thanks again Grant.
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Re: When out of CL Idle, why is my idle high sometimes?

Postby gslender » Wed Aug 08, 2012 1:33 pm

tomeric914 wrote:
At 1112 seconds, I was decelerating down a very long exit ramp which is why the RPMs didn't drop with the throttle closed.


Ok, well make sure you point where clearly in the log the issues exist, as I can't tell things like that and I'm left wondering why it behaves that way. Another thing - can you just duplicate the behaviour whilst free revving in neutral, holding revs high at 2500 and then letting the throttle go and the idle stays high?

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

Postby tomeric914 » Wed Aug 08, 2012 2:48 pm

gslender wrote:Ok, well make sure you point where clearly in the log the issues exist, as I can't tell things like that and I'm left wondering why it behaves that way. Another thing - can you just duplicate the behaviour whilst free revving in neutral, holding revs high at 2500 and then letting the throttle go and the idle stays high?

I'll try to explain where each hang is and what I was doing at that time. So far, I have only been pointing to the idle hangs.

I'm making your suggested changes now but won't get a chance to post a log for another 3-4 hours. I will try free revving to 2500 and letting the throttle go.
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Re: When out of CL Idle, why is my idle high sometimes?

Postby gslender » Wed Aug 08, 2012 3:06 pm

tomeric914 wrote:
gslender wrote:Ok, well make sure you point where clearly in the log the issues exist, as I can't tell things like that and I'm left wondering why it behaves that way. Another thing - can you just duplicate the behaviour whilst free revving in neutral, holding revs high at 2500 and then letting the throttle go and the idle stays high?

I'll try to explain where each hang is and what I was doing at that time. So far, I have only been pointing to the idle hangs.

I'm making your suggested changes now but won't get a chance to post a log for another 3-4 hours. I will try free revving to 2500 and letting the throttle go.


If you are having issues with the idle in normal driving, from cold to warm, then this is why the [mod] firmwares exist. I've introduced a lot of code (with the help from Ken and stuff that is in MS3) that better handles these issues. But simple hot engine, free revving and driving should be "mostly" fine with the standard release 3.2.1

I'm a picky bastard and don't believe the 3.2.1 release has enough smarts to be "good enough" but Ken is indeed right, that with more tuning and persistence, you can probably get it fairly close to "good enough" - note that this is a subjective term and your good enough and mine might differ.

Anywho - try the changes and be very clear about the issue you have as I clearly can't be chasing ghosts if the behaviour in the log is you holding the revs up with the clutch or other anomalies I can't possible know about. Sometimes taking cuts/snips of the log and uploading the very specific issue you are chasing helps focus the attention onto that point. When you look at a log there is so much going on it sometimes is impossible to see the forest for the trees.

Good luck ;-)

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

Postby tomeric914 » Wed Aug 08, 2012 7:23 pm

MSL and MSQ attached

gslender wrote:If you are having issues with the idle in normal driving, from cold to warm, then this is why the [mod] firmwares exist. I've introduced a lot of code (with the help from Ken and stuff that is in MS3) that better handles these issues. But simple hot engine, free revving and driving should be "mostly" fine with the standard release 3.2.1

Now that I'm close with my tune, I probably should start using your firmware. The hanging idle seems to always be with the engine semi-warm.

In the log below, I start my decel down that long exit ramp at 8417 sec and close the throttle at 8428 sec with the driveline engaged. At 8431 sec (roughly 3 sec later), the valve opens fully to 30.1 outside of CL idle and then decays to 0 after I have applied throttle at the bottom of the exit ramp.

Decel and throttle closed again with driveline engaged at 8460.5 sec, valve open again 3 sec later at 8463.45 sec

The next one is quicker at 8471.9 sec, followed by another shortly after but there was a small throttle 2% blip in that one.

Decel and throttle closed again with driveline engaged at 8603.7, valve open about 4 sec later at 8607.5

Decel and throttle closed again with driveline engaged at 8731, valve open.

The commonality that I see of the above 5 events is that they were all while decelerating, oil temp less than 140 deg F, and most took 3 seconds. I have two settings at 3 seconds which are the "Close delay(sec)" which I imagine closes the valve slowly over 3 seconds and "For this number of seconds (sec)".

Wait a second though, if I read the last two inputs of the "Closed loop idle valve settings" in a complete sentence, it reads like this:

"Leave valve closed above (rpm) 1600 for this number of seconds (sec) 3" or with better English, "Leave valve closed above 1600 RPM for 3 seconds." So after 3 seconds, the valve comes open if conditions aren't right for CL idle. Did I finally make sense of this?

So to simplify setting up CL idle, make the closed delay 0 so the valve always stays open and get the CL idle settings right so that it can enter CL idle even with the idle valve at max opening.

In my case:

Idle Open Duty is 30.1 and 1450 RPM
RPM with valve closed is 850
If I make the "Idle Activation RPM adder" 650, wouldn't that mean that I could enter CL Idle at 1500 RPM which would be above the Idle Open Duty RPM?

Also, with the engine fully warm (near the end of the MSL), I did the 2500 RPM rev test and the dashpot adder caught the RPMs every time and decayed as expected.

gslender wrote:I'm a picky bastard and don't believe the 3.2.1 release has enough smarts to be "good enough" but Ken is indeed right, that with more tuning and persistence, you can probably get it fairly close to "good enough" - note that this is a subjective term and your good enough and mine might differ.

I'm a picky bastard as well and want to understand the logic behind it all so I can make changes that make sense to me. I'm a helluva lot closer tonight than I've been thanks to your help.
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