Bouncy AFR at low throttle - why

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10-21-2008, 03:20 AM

Zaphod

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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

10-21-2008, 03:51 AM

Savington

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Zip your log and post it. I'd bet your AEs are kicking in.

10-21-2008, 04:35 AM

Zaphod

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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

datalog200810201925.zip (296.1 KB, 63 views)

10-21-2008, 07:31 AM

paul

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Last edited by paul; 10-21-2008 at 07:42 AM.

10-21-2008, 07:41 AM

paul

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How does sparkadvance go negative?

10-21-2008, 08:07 AM

Zaphod

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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

10-21-2008, 10:15 AM

Saml01

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Quote:

Originally Posted by paul

How does sparkadvance go negative?

Dont you know engines spin in reverse when you go backwards.

Quote:

Originally Posted by Zaphod

If you have -7 where I think you have it, then yea that could def be a problem.

10-21-2008, 10:29 AM

Zaphod

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Please keep in mind it's a MS2 not a MS1.

10-21-2008, 10:45 AM

Braineack

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Quote:

Originally Posted by Zaphod

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

10-21-2008, 11:01 AM

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Zaphod

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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