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Old 12-15-2011, 12:04 AM   #1
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Default Megasquirt idle surge and failed emissions

Yes, you may call me a Noob, I don't give a fck what you call me as long as someone can point me in the right direction to fix this idle surge: I sit in the car running Tuner Studio for the past 2 hours trying to resolve the cause of why my car just failed emissions. I've tried some settings in Tuner Studio but I don't want to fck with settings that may make it worse. The car idles fine when running rich (11.5 afr) but getting it back up above 13.5 makes is rev from 900 to 1100 rpm then pops a bit and drops back down to 900. Tried adjusting the idle screw on IAC, fuel VE table, spark table, idle speed targets... WTF did I miss or what should I try adjusting? Anyone in the Austin TX area I could bribe in helping me? Cash in hand!
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Old 12-15-2011, 11:39 AM   #2
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Please post a data log of the problem and a copy of your MSQ.
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Old 12-15-2011, 09:40 PM   #3
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If I had to guess, I'd wager you're running advanced timing at idle. OEM timing at idle is around 10 degrees, which generally idles nicely at stoich. A lot of the base maps I've seen come with idle cells around 17 degrees, which would only run smoothly at rich AFRs when I tried it on my '97 MS1 parallel.
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Old 12-15-2011, 10:22 PM   #4
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Yup, if that's 17* advanced timing and not 17* Fahrenheit, that's one of your major problems.

Select any and all idle cells and set them to a static 10*, and then a steady 15.0 AFR. Not sure what the popping and idle hunt is from.
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Old 12-16-2011, 02:57 PM   #5
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Thanks JNSHK and Curly! I'll try that ASAP. Sorry for the delay in getting back on here. I'm still a Noob when it comes to Megasquirt, not sure yet how to post datalog. I have some studying to do...
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Old 12-16-2011, 03:57 PM   #6
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Running smoother now, still a slight pop and idle drop every now and then but much better! I (think) I've attached the files you requested... Let me know if this is correct.
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File Type: msq 2011-12-16_13.52.13.msq (36.7 KB, 130 views)
File Type: msl 2011-12-16_datalog.msl (34.8 KB, 129 views)
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Old 12-19-2011, 04:14 PM   #7
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Quote:
Originally Posted by Matt Cramer View Post
Please post a data log of the problem and a copy of your MSQ.
Matt, Is this not what you requested?
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Old 12-20-2011, 10:01 AM   #8
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That's not a bad idle. You might want to adjust your spark table for a little more advance when RPM falls below 1000 to make it roll a little less.
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Old 01-04-2012, 01:11 PM   #9
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Quote:
Originally Posted by Matt Cramer View Post
That's not a bad idle. You might want to adjust your spark table for a little more advance when RPM falls below 1000 to make it roll a little less.
Thanks Matt! I'll keep playing with the settings...
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Old 01-04-2012, 08:17 PM   #10
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I don't have access to TunerStudio at work. But if your map is similar to the picture there jump at 14 and 19 KPA between 500-900 RPM is pretty big from 42 to 51 and then 54. The change in fuel will make the idle hunt if it goes below 900 RPM. It is generally the best to keep the VE around idle pretty consistent. Just my 2cents.
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