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Old 04-01-2013, 06:16 PM   #1
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Default MS3 Idle issue

Hi! i'ved got my car out 2 days ago w/reverant ms3, i'ved been autotuning fuel, things are going good so far! the car is pulling good!

But a have a few issue
The first one beeing that i can't start it unless i give it a bit of throttle

The second one is that when i get off of load, and put it into neutral(or clutch) the idle goes wayyy down to like 300rpm, and one of 3 time, it dies! the only way i can save it, is too give a bit of throttle before the rpm goes down, if i do this, the rpm goes back to idle no problem.

I was thinking it may be related, idle setting maybe.

Got a closed-loop idle setting screenshot, if that is for any help!
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MS3 Idle issue-clsd-loop-idle.jpg  
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Old 04-01-2013, 06:18 PM   #2
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1. sounds like you are injecting too much fuel during cranking
2. use last known value, make sure your fuel maps dont go lean in low load/rpm cells, allow overrun to inject fuel again around ~1800RPM.
3. tune PID
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Old 04-01-2013, 06:29 PM   #3
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Here the fuel map, VEAL tuned what i was able to do.
I can see it pull out alot of fuel in the 3400-4800 zone wich is cruising zone.

Were can i find that overrun?
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MS3 Idle issue-fuel-table.jpg  

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Old 04-01-2013, 09:06 PM   #4
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datalog the droop.

basic settings > general settings

return fuel under 1700 RPM



are you using the idle ve table?
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Old 04-01-2013, 09:48 PM   #5
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Quote:
Originally Posted by Braineack View Post
datalog the droop.

basic settings > general settings

return fuel under 1700 RPM



are you using the idle ve table?
Nop, idle ve table is off.
I'm going to datalog as soon as i can get it out again, temperature around here aren't pretty!

Overrun return fuel was a 1550, climbed it back to 1700!
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Old 04-01-2013, 09:52 PM   #6
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Learning from this. Thanks for the help Brain.
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Old 04-01-2013, 11:15 PM   #7
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i had droop due to the fuel not being turned back on fast enough. the was mechanical latency from the rpm point i had set and when the afrs would register again. ramping upthe dashpot didn't help since no fuel was there to stabilize idle speed.
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Old 04-02-2013, 03:43 AM   #8
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Also set the dashpot decay factor to 0, there appears to be a bug in there that causes the dashpot value to be removed, not added.
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Old 04-02-2013, 04:48 AM   #9
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And there's zero documentation on what that value is actually useful for!
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Old 04-02-2013, 07:44 AM   #10
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So i lowered fuel in the starting area in the VE table, plus "tuned" PID according to Megamanual, and switch a few ajustement you guys told me to try, now only waiting.

Now all i need is the temperature to cooperate! was about 55 sunday, now 25 and snowing -_-'. I'll give some update and some logs as soon as possible!
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Old 04-02-2013, 09:14 AM   #11
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Quote:
Originally Posted by richyvrlimited View Post
And there's zero documentation on what that value is actually useful for!
it's just like any other decay, the time it takes for the dashpot adder to fizzle out.

What firmware is the bug on? I think I'm on 1.2.0? But I haven't driven the car since like October, but will probably be actually paying attention to it soon.

But having a dashpot that works would acutally be nice.
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Old 04-02-2013, 10:56 AM   #12
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Quote:
Originally Posted by Braineack View Post
it's just like any other decay, the time it takes for the dashpot adder to fizzle out.
I get that, but why would you ever want the dashpot to decay before it's even been used? MegaSquirts documentation is seriously lacking, it used to be bad, but it's terrible now.

Set the decay to zero and the dashpot stays as you'd expect it to. There's a bug where it actually removes duty rather than adds it, but you don't need/want any decay anyway so just disable it.

It's still present on the latest 1.2 release, no idea if 1.3 beta has fixed it, not tried it yet.
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Old 04-02-2013, 11:01 AM   #13
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I dunno why they always have dashpot issues. For a while it was broken between like alpha15 and alpha24 or something.
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Old 04-03-2013, 09:42 PM   #14
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So i got thing dialed in better!
Quick tuned PID, put more fuel in the very low load under 2900rpm area.
Idle seems to be alot better, no more significant drop, the bieggest drop^i've seen was at about 650-700rpm!
Got some fuel off in the starting zone, seem to have help alot too!(see table below)

I noticed that, the engine wants to stall in idle when i get both windows up at the same time(power windows of course) is there a way to compensate for the draw of power?

Seriously thanks for the tips, seem to have help alot!
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MS3 Idle issue-fuel-table.jpg  
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Old 04-03-2013, 10:47 PM   #15
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voltage idle compensation table.
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Old 04-03-2013, 11:06 PM   #16
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Quote:
Originally Posted by Braineack View Post
voltage idle compensation table.
ha, oh, my bad, did'nt see that one! n00b question!!!

Thanks!
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Old 04-05-2013, 07:59 AM   #17
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I still got some intermitent idle droop!, but alot ALOT less!
Now it seems to be that its dark(fog light/low beams/heater fan/radiator fan/radio is on)
Do one of you guys could send me you idle voltage compebsation graph, to get an idea where i'm standing?

Thanks!
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Old 04-05-2013, 09:48 AM   #18
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what year car do you have?
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Old 04-05-2013, 06:44 PM   #19
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99 NB
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Old 04-05-2013, 09:47 PM   #20
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ah. your voltage never drops.
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