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Bad Missing Tooth Wheel 
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The other night while Peter was running engine number 12, about which he's yet to post, he was having some sync troubles. He first tried moving the sync setting for missing teeth setups to the max sensible value of 2048. No luck. We then got a freeems bin log and saleae LA log from it. The bin log was amazingly consistent, rise in RPM, desync, resync, rise, repeat. The screen shots are below:

Image

Image

Image

That's the wheel involved, post machining, pre tests. Before machining it had pointy triangle teeth. DIYAutoTune sell them that way. :-o

The values for the stretch before during and after missing from the LA screeny are here:

Code:
2.9120625
2.82475
2.772
2.8385
7.3986875
1.9526250
3.1124375
3.012
3.0403750

If we look at the ratios from one to the next we get:

Image

As you can see, things don't look right.

What should be close to 1:1, 1:1, 1:1, 1:1, 1:2, 2:1, 1:1, 1:1, 1:1, 1:1 is wildly different. The trouble isn't the slightly wider missing, it's the combination of wide missing and narrow post missing. If you compare the long with the average you get ~3.8, but if you compare the wide with the narrow after it you get ~10 :-o

Sure as the sun will shine tomorrow, the error code was: 66, or TooWideNarrow which I've aliased to the name noiseAppearedWayTooEarlyAsIfItWasAVRToothButWasnt because that's the most likely cause.

DIYAutoTune FTL.

Fred.

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Wed Jun 13, 2012 3:56 pm
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The gap that I analysed is the one starting at 10.881481125, btw.

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Wed Jun 13, 2012 4:00 pm
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The above posts are wrong. It's not that bad, I'm just tired and confused. Sorry for the fud.

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Wed Jun 13, 2012 10:10 pm
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1N4001 - Signed up

Joined: Thu May 29, 2008 1:23 am
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Peter wrote:
Image

Fred wrote:
Before machining it had pointy triangle teeth. DIYAutoTune sell them that way. :-o

It's possible that particular sensor cannot operate well with that tooth profile/proximity.


Thu Jun 14, 2012 4:27 am
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Correct numbers and graph of inter edge times (red), ideal times based on the average (blue) and expected times based on the last (yellow):

Image

Error % graph is inset, values here:

Code:
3.091
1.903
2.399
30.327
89.455
59.398
3.335
0.942

Which seems unfair.

I don't think it's reasonable to decrease requirement on tooth following first after missing (second after missing) due to error in first after missing. That's a timing error if you get a schedule from it.

However, I don't think what I'm doing now is right either. I should likely take the absolute value instead, which would yield these errors:

Code:
2.998
1.867
2.399
30.327
47.217
59.398
3.227
0.942

Still not good enough for 50% tolerance (max reasonable) to allow running, but closer, that's for sure.

Fred.

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Thu Jun 14, 2012 2:39 pm
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Chart for the potential revised error scheme:

Image

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Thu Jun 14, 2012 2:48 pm
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MotoFab wrote:
It's possible that particular sensor cannot operate well with that tooth profile/proximity.

You're a bit late to the party!

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Thu Jun 14, 2012 2:49 pm
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TO92 - Vaguely active

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Did u use a hall sensor?

IF(hall) {

Hall sensors generally are bad at reading ramped edges.
At this thread -> viewtopic.php?f=15&t=491
4th. post where JB explains how hall and vr sensors work.

This is kinda prefect example how your ignition will jitter some degrees with hall-sensor and a "bad" toothed wheel.
}


Thu Nov 01, 2012 11:12 am
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Thing is, DIYAutoTune supply a hall sensor with that wheel. I could be mistaken about that, and I'm sure Peter will confirm/deny shortly.

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Fri Nov 02, 2012 12:41 am
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First I tried the hall sensor from diyautotune, and then I tried a VR sensor off of a Honda. Finally I just took the 12 tooth trigger wheel off of the Honda, and cut one tooth off of it.

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Fri Nov 02, 2012 7:01 pm
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