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Old 10-21-2008, 04:20 AM   #1
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Default Bouncy AFR at low throttle - why

Hi guys,

as I am in the process of dialing in my VE tables, I made a lot of logs.
The VEs seem to get dialed in quite good - what confuses me is the bounces in the AFR when I have throttle very low (like next to 2-5) or when I let go of the throttle:

pic


You can see the spikes, where AFR goes from very low to very high. If I get in the cruise or boost area, the AFRs are very steady and nearly perfect.

One more question - what is Spark advance in MLV showing me - it doesn't fit my spark table at all. In the pic it sits at 4 and the advance table says 24.5? Or did I choose the wrong value - what other value shows me real spark timing then?

Thanks
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Old 10-21-2008, 04:51 AM   #2
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Zip your log and post it. I'd bet your AEs are kicking in.
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Old 10-21-2008, 05:35 AM   #3
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O.K. though this is not a very special log, I attach it.
It can very well be, that it is the AE kickin in...

https://www.miataturbo.net/forum/att...1&d=1224578175

Any ideas to the spark question?

Thanks
Attached Files
File Type: zip datalog200810201925.zip (296.1 KB, 58 views)
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Old 10-21-2008, 08:31 AM   #4
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Last edited by paul; 10-21-2008 at 08:42 AM.
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Old 10-21-2008, 08:41 AM   #5
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How does sparkadvance go negative?
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Old 10-21-2008, 09:07 AM   #6
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That is what I am not sure about.

I just add this information - my trigger angle/offset is at -7.00 degrees.
(That was how I did reach 10 BTDC with the trigger wizard.)
Maybe it has something to do with this?

Greets
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Old 10-21-2008, 11:15 AM   #7
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Quote:
Originally Posted by paul View Post
How does sparkadvance go negative?
Dont you know engines spin in reverse when you go backwards.

Quote:
Originally Posted by Zaphod View Post
That is what I am not sure about.

I just add this information - my trigger angle/offset is at -7.00 degrees.
(That was how I did reach 10 BTDC with the trigger wizard.)
Maybe it has something to do with this?

Greets
If you have -7 where I think you have it, then yea that could def be a problem.
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Old 10-21-2008, 11:29 AM   #8
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Please keep in mind it's a MS2 not a MS1.
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Old 10-21-2008, 11:45 AM   #9
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Quote:
Originally Posted by Zaphod View Post
One more question - what is Spark advance in MLV showing me - it doesn't fit my spark table at all. In the pic it sits at 4 and the advance table says 24.5? Or did I choose the wrong value - what other value shows me real spark timing then?

there are supposed to match.

I suggest you start posting the the MS-II forums at msextra.com
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Old 10-21-2008, 12:01 PM   #10
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O.K. and the point goes to... Matt at DIYautotune!

He emailed me:

<You probably have some other table active that is modifying your
<ignition advance.

Well, I hadn't seen, that my Knock sensing was turned on (because this is hidden in a little sub-menu) which I haven't got at this point and I suppose the MS was thinking, that my car is knocking a lot...

Switched it out and get sensible readings with Megatune.

Now to the original topic - someone?

Greets
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