Nexia with 'RED TOP' C20XE

What engine are you torturing? Is it inside some car?
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JRD McLAREN
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Nexia with 'RED TOP' C20XE

Post by JRD McLAREN »

So ...

I need to help with my current config.
Engine "cutt-off" on drag race, when I'm shift up, and I can't see why..
(tps 100 to 0 to 100)

Can anybody help me explain why..??

RPM, VE, TPS and other things looks good in log.
(due to "over-fuel" .. or why ..?)

Drag race start at aprox. 260sec

Thanks.
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stefanst
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Re: Nexia with 'RED TOP' C20XE

Post by stefanst »

It looks like when you lift, the fuel cuts off and then comes back on for one quick blip and then it's off for good.
This is just a wild guess, but it may have to do with fuel cutoff. Maybe you exposed a glitch, or maybe your settings are screwy. Your rpm settings with 2500rpm and 2300rpm don't seem to make much sense anyway. I would turn off the fuel cut-off and see if that helps.

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Re: Nexia with 'RED TOP' C20XE

Post by AndreyB »

Reminder about https://rusefi.com/online/ as tune & logs sharing platform :)
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mck1117
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Re: Nexia with 'RED TOP' C20XE

Post by mck1117 »

You're hitting fuel cut because it would be over 100% duty cycle.

Notice how the "fuel: base" channel is up at ~38ms, when there are only 28.5ms worth of time to inject at the current engine speed.
image.png
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Now: why are we trying to add all that extra fuel? I think something is going wrong with engine load acceleration enrichment. All your sensors look OK, so I don't see where that extra fuel is coming from other than engine load accel enrichment.

It may be worth disabling engine load accel, and relying on exclusively wall wetting enrichment. It seems for lots of engines using tau = 0.3, beta = 0.3 is a reasonable starting point. Beta controls how much correction happens immediately after a change, and tau controls how long that adjustment lasts for.

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Re: Nexia with 'RED TOP' C20XE

Post by JRD McLAREN »

OK ...
So, now I see 3 vriants of enrichment.
TPS , Wall wetting and Engine Load.

Now I need to do, is try to use one of them .. (RIGHT .. ?)
Set all to zero in Engine load, then Engine Load Acceleration Tapper Graph will be ignored - at all

Try to disable TPS enrichment, same way..
(tps map have number 37 :) )

..and then try to run ...
My engine have ITB, just for record.
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JRD McLAREN
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Re: Nexia with 'RED TOP' C20XE

Post by JRD McLAREN »

So ..
Can anybody check this ..??

(I have no idea, how it works and what that numbers are.. ) :roll:
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AndreyB
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Re: Nexia with 'RED TOP' C20XE

Post by AndreyB »

@JRD McLAREN next time you post tune and logs as attachment I will remove those.

Next time please try posting your tune and logs on rusEFI online at https://rusefi.com/online
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JRD McLAREN
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Re: Nexia with 'RED TOP' C20XE

Post by JRD McLAREN »

OK...

Tune is online ...

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Re: Nexia with 'RED TOP' C20XE

Post by mck1117 »

Something like this will disable everything other than wall wetting enrichment.
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JRD McLAREN
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Re: Nexia with 'RED TOP' C20XE

Post by JRD McLAREN »

Thanks, I will test it ..

..and when I can use TPS accel ..??

Maybe will be better, if anybody write documentation .. on wiki page ..

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Re: Nexia with 'RED TOP' C20XE

Post by AndreyB »

JRD McLAREN wrote:
Fri Aug 07, 2020 5:33 pm
Maybe will be better, if anybody write documentation .. on wiki page ..
Please confirm that you have located https://rusefi.com/wiki/index.php?title=Manual:Software:Fuel_Control and https://github.com/rusefi/rusefi/wiki/Acceleration_Compensation
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JRD McLAREN
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Re: Nexia with 'RED TOP' C20XE

Post by JRD McLAREN »

I found these pages sometime before.

It looks little bit outdated.
and some description for "numbers" Length Cycles, Accel Threshold will be helpful.

I have no idea, if it must be 0.55 or 1.74 or 34.578 ...
(need some hint for these settings)

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AndreyB
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Re: Nexia with 'RED TOP' C20XE

Post by AndreyB »

Gotcha, will try to improve under https://github.com/rusefi/rusefi_documentation/issues/74

Thank you for your patience :)
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JRD McLAREN
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Re: Nexia with 'RED TOP' C20XE

Post by JRD McLAREN »

Thanks.

I will try some settings this weekend, from other configs.
(Online "archive" )

Maybe one wish or hint for accel enrichment strategy ...
about MAX fuel value ...

As mck1117 described me, I have fuel cut due to max duty cycle ...
required 38ms from TPS>TPS table, but max available inj. time is 28ms.

Is able "cut" or "shrink" maximal accel enrichment time to current max. available injection time ( duty cycle 100% ) . ..??
or ...
is possible have inj. duty cycle over 100% when accel enrichment occur / run ..??
WITH NO FUEL CUT

(it is my idea at this moment and if it is not possible, please ignore it 8-) )

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Re: Nexia with 'RED TOP' C20XE

Post by mck1117 »

JRD McLAREN wrote:
Fri Aug 07, 2020 7:55 pm
Maybe one wish or hint for accel enrichment strategy ...
about MAX fuel value ...

As mck1117 described me, I have fuel cut due to max duty cycle ...
required 38ms from TPS>TPS table, but max available inj. time is 28ms.

Is able "cut" or "shrink" maximal accel enrichment time to current max. available injection time ( duty cycle 100% ) . ..??
or ...
is possible have inj. duty cycle over 100% when accel enrichment occur / run ..??
WITH NO FUEL CUT

(it is my idea at this moment and if it is not possible, please ignore it 8-) )
That's a pretty good idea - I'm already working on improving this part of the firmware, so I'll add that to my list of things to consider. Thanks!

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Re: Nexia with 'RED TOP' C20XE

Post by JRD McLAREN »

;)

So this is my actual test settings..
engine revs up relatively good ...
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Re: Nexia with 'RED TOP' C20XE

Post by AndreyB »

:(

Please guess why :(
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