Bad Missing Tooth Wheel

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Fred
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Bad Missing Tooth Wheel

Post by Fred »

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: Select all

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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Re: Bad Missing Tooth Wheel

Post by Fred »

The gap that I analysed is the one starting at 10.881481125, btw.
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Re: Bad Missing Tooth Wheel

Post by Fred »

The above posts are wrong. It's not that bad, I'm just tired and confused. Sorry for the fud.
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MotoFab
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Re: Bad Missing Tooth Wheel

Post by MotoFab »

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.
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Re: Bad Missing Tooth Wheel

Post by Fred »

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: Select all

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: Select all

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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Re: Bad Missing Tooth Wheel

Post by Fred »

Chart for the potential revised error scheme:

Image
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Re: Bad Missing Tooth Wheel

Post by Fred »

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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Re: Bad Missing Tooth Wheel

Post by peki »

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.
}
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Re: Bad Missing Tooth Wheel

Post by Fred »

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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Re: Bad Missing Tooth Wheel

Post by Peter »

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.
:-p
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