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Author Topic: TVUB modification wrong LTFT  (Read 4167 times)
tao13
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« on: September 18, 2020, 07:49:18 AM »

Hi all. I made for my 730cc bosch injectors only next modification to see what happen: decreased all TVUB values
Before modification :
3.2987 1.9307 1.3387 1.0000 0.8720 and LTFT was -3.2

After
3.2987 1.3307 1.0293 0.7707 0.6907 and LTFT is 2.3

It is normal the car run lean with tvub lower?



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nyet
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« Reply #1 on: September 18, 2020, 11:31:56 AM »

Hi all. I made for my 730cc bosch injectors only next modification to see what happen: decreased all TVUB values
Before modification :
3.2987 1.9307 1.3387 1.0000 0.8720 and LTFT was -3.2

After
3.2987 1.3307 1.0293 0.7707 0.6907 and LTFT is 2.3

It is normal the car run lean with tvub lower?


Considering that is the purpose of TVUB, yes. It should be tuned along side KRKTE.

All of this has been covered in depth pretty extensively
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tao13
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« Reply #2 on: September 18, 2020, 12:57:15 PM »

Nowhere in this forum i find this conclusion: tvub lower , engine works lean.
What i study in all injectors datasheet who i saw, smaller injectors had tvub values lower than bigger injectors but only on 14v and 16v. At 8v,10v and 12v the tvub is higher for smaller injectors than bigger injectors.
I don't find a template or a rule.
For my injectors i don't find the bosch specification and i use the 750cc bosch specification.

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Auriaka
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« Reply #3 on: September 18, 2020, 01:02:54 PM »

There is no rule of TVUB having a correlation to injector size...

Krkte is relation to injector size, TVUB is the coil deadtimes or offset for pulsewidth needed for desired fuel versus voltage.

Each injector type and size is unique and ideal TVUB will vary. Typically ev14 TVUB will be lazy with larger values compared to other types of injectors like DEKAS.

Tvub is voltage offset/ deadtime
Krkte is injector factor for size/output of injector

Temin is minimum stable reproducible pulsewidth.
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nyet
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« Reply #4 on: September 18, 2020, 03:32:33 PM »

Deadtime is the amount of time the ECU has to add to the injector open time to compensate for the amount of time it takes for the injector to open.

For very small injector open times (e.g. idle), this has a large effect.

For large open times (e.g. WOT), this has less of an effect.

If your idle vs part trims are drastically different, your TVUB is wrong.

This is covered in both the FR extensively, and just about all resources regarding fuel injectors, duty cycle, on time, etc.
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Please do not ask me for tunes. I'm here to help people make their own.

Do not PM me technical questions! Please, ask all questions on the forums! Doing so will ensure the next person with the same issue gets the opportunity to learn from your experience.
tao13
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« Reply #5 on: September 18, 2020, 11:48:53 PM »

Thanks Auriaka and NYET!
I leave actual TVUB like 750cc injectors , because i saw the STFT stay between -5 and +5 (before with high values of TVUB fluctuate between -15 and +10) and i add some fuel for LTFT from KRKTE to made it a little rich , somewhere to -1.6.
Sound good for you?
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nyet
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« Reply #6 on: September 19, 2020, 01:00:06 AM »

without saying if you are talking about idle or part trims your numbers aren't helpful
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Please do not ask me for tunes. I'm here to help people make their own.

Do not PM me technical questions! Please, ask all questions on the forums! Doing so will ensure the next person with the same issue gets the opportunity to learn from your experience.
tao13
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« Reply #7 on: September 19, 2020, 12:21:46 PM »

my "Dear friend Nyet" STFT is short trim  = idle adaption  and it is between -15 and +10 and LTFT is partial adaption and it is 2.3
i get this like a joke
i need some advice and you again and again get me like a joker
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Auriaka
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« Reply #8 on: September 19, 2020, 12:44:49 PM »

You have been spoon fed the information.
NYET doesnt screw around with people, and legitimently tried to help, as did I.

If your ecu is wideband (as its not stated or listed in yhis thread) pay attention to your logged lambda control values via me7logger.

There is nothing wrong with the information that you have been given. It may be time to evaluate your components for leaks or other mechanical issues as you cant tune around them. 

Its a DIY site, the information is here, figure it out.
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nyet
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« Reply #9 on: September 19, 2020, 01:21:48 PM »

my "Dear friend Nyet" STFT is short trim  = idle adaption  and it is between -15 and +10 and LTFT is partial adaption and it is 2.3
i get this like a joke
i need some advice and you again and again get me like a joker

STFT is just short term trim, not idle adaptation. Adaptations are (by definition) long term (LT)

There is one STFT (current trim, whether your are idling or not - its short term) and two LTFTs, one for idle and one for part throttle. Your understanding of the nomenclature is incorrect.
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ME7.1 tuning guide (READ FIRST)
ECUx Plot
ME7Sum checksum checker/corrrector for ME7.x

Please do not ask me for tunes. I'm here to help people make their own.

Do not PM me technical questions! Please, ask all questions on the forums! Doing so will ensure the next person with the same issue gets the opportunity to learn from your experience.
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