Huge CVT spike at the hit in Mychron data

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Huge CVT spike at the hit in Mychron data

Postby csracing » Wed May 02, 2018 8:59 pm

I'm going through some data logs from this past weekend and noticed that I have a massive CVT spike at the hit of the throttle. It goes off the chart but the data is showing something like 2500 but then falls to something reasonable after the car has moved a few feet. Can't say I've noticed this before, but I've probably not been paying attention.
Here's the graph with just the CVT data. Everything else looks normal.

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Re: Huge CVT spike at the hit in Mychron data

Postby WILD BILL » Wed May 02, 2018 9:45 pm

All mine have always looked like that as well.

I stopped even looking at it as its not really anything I use for judging performance or tuning the car.
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Re: Huge CVT spike at the hit in Mychron data

Postby csracing » Wed May 02, 2018 9:48 pm

I've never used it either, but clicked on it and noticed what looked to be kind of strange so I thought I'd ask.

Thanks
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Re: Huge CVT spike at the hit in Mychron data

Postby RNorton » Sat May 05, 2018 9:37 pm

When the car is stationary area your theoretical CVT is infinity, as the car starts moving your CVT starts to appear normal.

CVT is basically Engine RPM / Shaft Ratio

So with the engine running and the shaft stationary you have some number divided by a very small number (or zero).
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Re: Huge CVT spike at the hit in Mychron data

Postby slowgoat » Mon May 07, 2018 10:20 am

What is wrong with this or how do you think it should be ?
Looks perfectly fine to me
The flat line at the top is the belt slipping, as the clutch starts coming in the cvt lowers, Which is correct
Honestly looks a lot better than most I have ever seen
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Re: Huge CVT spike at the hit in Mychron data

Postby zrt-racing » Sun Jul 29, 2018 5:30 pm

WILD BILL wrote:All mine have always looked like that as well.

I stopped even looking at it as its not really anything I use for judging performance or tuning the car.


Not use CVT info for tuning???
Then your missing a whole piece of the puzzle running/tunning your car.
This is one of the first things i go to if we ever have an issue, especially at the hit.
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Re: Huge CVT spike at the hit in Mychron data

Postby RNorton » Sun Jul 29, 2018 7:43 pm

Anything that goes upward after the hit is a partial backshift and I would tend to prevent it.

It could mean a spin, soft secondary spring, or too high of helix angle.
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Re: Huge CVT spike at the hit in Mychron data

Postby Twin daddy » Thu Aug 09, 2018 12:41 pm

im going to go out on a limb and say that most don't even know what CVT is, I for one, have no clue how to read the CVT graph, but am very ready to learn anything that could help me, so if any of you know where there is some literature or anything someone has put together to help read the CVT graph. Please share.
Thank you
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