MS3 Gold - Tuning to catch an idle after rpm drop

goodysgotacuda · Post by **goodysgotacuda** » Wed Jul 12, 2017 5:21 pm

Hello

I am getting my 5.7L Hemi running on a MS3 Gold box and have managed to make the idling tune reasonable, it still does hunt slightly in various areas that I have yet to sort out.

I am trying to get the engine to catch an idle again as the rpms drop from a 1500rpm+ throttle close, it stumbles and dies soon thereafter. Any pointers on what to look for or options to turn on?

Thanks-

aus370 · Post by **aus370** » Thu Jul 13, 2017 5:21 am

I'm not much of a tuner but heres a few things I've read that helped me . Around the RPM you want it to idle : keep the VE table cells the same value : a couple of cells either side above and below , Do the same for the ign table , but make them just a little higher in the far left column that helps prevent a stall . half to one degree should be enough . You can always come back and fine tune this stuff later.

I found stalling when jumping of the throttle can be helped, by watching the trace in the VE table and the AFR's : you might find some cells that are causing lean outs .

goodysgotacuda · Post by **goodysgotacuda** » Thu Jul 13, 2017 7:06 am

Thanks for the feedback. I'll post screen shots of my tables this evening

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goodysgotacuda · Post by **goodysgotacuda** » Fri Jul 14, 2017 5:33 am

Any other suggestions?

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billr · Post by **billr** » Fri Jul 14, 2017 8:21 am

Umm... post an MSL?

I don't think of that as being "another" suggestion, as it is so prominently displayed every time you make a post/reply!

(Admin: Maybe that request for the MSQ and MSL should be in flashing-red text? Or put this :msq:

there?)

goodysgotacuda · Post by **goodysgotacuda** » Fri Jul 14, 2017 8:54 am

billr wrote:Umm... post an MSL?

I don't think of that as being "another" suggestion, as it is so prominently displayed every time you make a post/reply!

(Admin: Maybe that request for the MSQ and MSL should be in flashing-red text? Or put this there?)

I apologize for being new on this, I've been working with a running car for about a week and have no prior megasquirt experience. I assume a .msl is a log file and will work on making that available. I have not logged anything as of yet.

My hope was to receive generic tuning rules of engagement for something like this. A compensation value, adding/removing fuel to those parts of the table, etc. I'll get a .msl together.

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ChevelleFan · Post by **ChevelleFan** » Fri Jul 14, 2017 10:21 am

goodysgotacuda wrote: My hope was to receive generic tuning rules of engagement for something like this. A compensation value, adding/removing fuel to those parts of the table, etc. I'll get a .msl together.

First off, welcome! We were all new once. So, with all due respect: generic tuning rule of engagement (on this site): always post a log (.MSL) and tune (.MSQ). You'll more than likely get a specific answer, and usually an explanation with it. We are only as good at answering your questions as the information you provide us. The log and tune will give the complete information. (as an example, if you're having trouble with idle, focusing on VE table/idle settings, and we see a noisy throttle-position sensor reading, tripping AccelEnrich)

As the graphic says, "otherwise we are just guessing" As a group, the people here are happier to do better than guess.

Lastly, as much as we want to see your MSL/MSQ, a pic or two of your car/engine will usually help get some attention. Or maybe that's just me.

-Dave

goodysgotacuda · Post by **goodysgotacuda** » Fri Jul 14, 2017 11:19 am

ChevelleFan wrote:
goodysgotacuda wrote: My hope was to receive generic tuning rules of engagement for something like this. A compensation value, adding/removing fuel to those parts of the table, etc. I'll get a .msl together.
First off, welcome! We were all new once. So, with all due respect: generic tuning rule of engagement (on this site): always post a log (.MSL) and tune (.MSQ). You'll more than likely get a specific answer, and usually an explanation with it. We are only as good at answering your questions as the information you provide us. The log and tune will give the complete information. (as an example, if you're having trouble with idle, focusing on VE table/idle settings, and we see a noisy throttle-position sensor reading, tripping AccelEnrich)

As the graphic says, "otherwise we are just guessing" As a group, the people here are happier to do better than guess.

Lastly, as much as we want to see your MSL/MSQ, a pic or two of your car/engine will usually help get some attention. Or maybe that's just me.

-Dave

Thanks for the feedback and the warm welcome Dave, I'll get some better information posted over the weekend.

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piledriver · Post by **piledriver** » Sat Jul 15, 2017 2:00 am

Yummy car!
'Yellow is the perfect color for those. Or flat black... or some combination of yellow with flat black accents/hood etc.

Without an actual log and tune file, some generic info gleaned from here and working on my setups for a few years, 80 mile/day daily driver.

1) Anything newer than an MS1 should probably be using idle timing and idle VE tables, there is no need for any funny business in the main tables for idle for the last 5 or so years at least.

You may need to raise the min value for your IAC, as well as set up the idle target table and initial value tables ...values for same.
There is also a setting for "dashpot" adder that kicks the IAC up a few % when idle operations kick in.
Do that AFTER setting up IAC minimum/max and initial values, if needed.

You can use the automagic closed loop idle detection or force it to kick in with MAP/RPM etc settings.
The latter can be faster.

The delay times must be reasonable for the PID ramp to target and crank to run times.
The cranking settings also help determine the recovery preventing stalls.
The first column of the VE table and spark tables IIRC is a primary driver of this.
(someone I'm sure will correct me if that is no longer true)

One also MUST set up the new "engine state" settings, this sounds daunting but it took like 30 seconds, really just a matter of playing with the numbers while playing with the throttle to see if the "mode" is what you expect for the conditions. I think I ended up lowering something a few %, rest still defaults and seem sane.

As I am putting in an automatic at the moment that will probably need more work.

goodysgotacuda · Post by **goodysgotacuda** » Sat Jul 15, 2017 8:14 am

This first one is a warm idle hunt that it seems to be doing and it will eventually stall itself. No power steering, fan, a/c inputs adding load to it.

goodysgotacuda · Post by **goodysgotacuda** » Sat Jul 15, 2017 8:17 am

This one I am still working through with holding a constant TPS and it surging, then it has a hard time catching idle and dies.

goodysgotacuda · Post by **goodysgotacuda** » Sat Jul 15, 2017 8:18 am

goodysgotacuda · Post by **goodysgotacuda** » Mon Jul 17, 2017 11:48 am

Hopefully these files work correctly.

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goodysgotacuda · Post by **goodysgotacuda** » Wed Jul 19, 2017 5:43 am

Bump, I could still use any suggestions to help this thing catch idle again.

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ChevelleFan · Post by **ChevelleFan** » Wed Jul 19, 2017 6:38 am

So, I see a couple things..

1) When you're holding it at ~1800 RPM, I'm seeing an AFR of 17.5, which is pretty lean. Much leaner than your AFR table is setup for. When the AFR is spiking richer, thats when RPM picks up. The VE values you're hovering around range from 20-31. I think VE table needs work here, however...

2) Under General Settings, under Incorporate AFR Target, you're set to "Dont include AFR target". This basically ignores the AFR table. Set to "Include AFR target" After doing this, I would re-run VE Analyze Live to let it re-adjust your VE entire table. Go for a drive, and try to hit all areas of the table. Once that is complete, you can make any manual tuning adjustments directly with the AFR table, which is much more intuitive.

-Dave

goodysgotacuda · Post by **goodysgotacuda** » Wed Jul 19, 2017 4:20 pm

ChevelleFan wrote:So, I see a couple things..

1) When you're holding it at ~1800 RPM, I'm seeing an AFR of 17.5, which is pretty lean. Much leaner than your AFR table is setup for. When the AFR is spiking richer, thats when RPM picks up. The VE values you're hovering around range from 20-31. I think VE table needs work here, however...

2) Under General Settings, under Incorporate AFR Target, you're set to "Dont include AFR target". This basically ignores the AFR table. Set to "Include AFR target" After doing this, I would re-run VE Analyze Live to let it re-adjust your VE entire table. Go for a drive, and try to hit all areas of the table. Once that is complete, you can make any manual tuning adjustments directly with the AFR table, which is much more intuitive.

-Dave

Thanks Dave. The car just got a windshield in it today, I hope to get out on the road and do some basic tuning this weekend.

goodysgotacuda · Post by **goodysgotacuda** » Wed Sep 13, 2017 7:44 pm

Hello again, I am still working through some low rpm troubles and am hoping someone can lend some insight to my issue. My idle is pretty decent and catches well if I come immediately off throttle while depressing the clutch. The ECU sees me get off the throttle, runs the IAC dashpot adder and catches the idle just fine.

My issue is during engine braking, no throttle input and I depress the clutch. Removing that load from the engine with no change in TPS [0%] causes the engine to stumble at low rpm hard, but it usually catches. This becomes more pronounced if I have an added load, like the fan kicks on or I am applying power steering load.

The attached log is of low speed driving in first. I hold a few % of TPS, close the throttle, then depress the clutch. You'll see the RPM bottom out around 500, then catch. The IAC sees the falling rpm and tries to catch up, perhaps too late? I am not sure where to head on this one.

2017-09-09_19.54.54.msq

2017-09-13_20.22.32_lowidle.msl

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