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-   -   Bouncy AFR at low throttle - why (https://www.miataturbo.net/megasquirt-18/bouncy-afr-low-throttle-why-27334/)

Zaphod 10-21-2008 03:20 AM

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
http://www.ingenieure-reichel.de/upload/MS/logbild.jpg

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

Savington 10-21-2008 03:51 AM

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

Zaphod 10-21-2008 04:35 AM

1 Attachment(s)
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

paul 10-21-2008 07:31 AM

.

paul 10-21-2008 07:41 AM

How does sparkadvance go negative?

Zaphod 10-21-2008 08:07 AM

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

Saml01 10-21-2008 10:15 AM


Originally Posted by paul (Post 321997)
How does sparkadvance go negative?

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


Originally Posted by Zaphod (Post 322005)
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.

Zaphod 10-21-2008 10:29 AM

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

Braineack 10-21-2008 10:45 AM


Originally Posted by Zaphod (Post 321976)
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

Zaphod 10-21-2008 11:01 AM

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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