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Discussion Starter · #1 ·
Hi guys
I have GTR 2017
With bl1050x turbo and short block upgraded
Fuel system is viscount stg2 with hardwire
Injectors 1300ID
Clutch 7/7 dadson with basket B only

on the fuel pump the car was running perfect on high rpm (26 psi) more or less

But when I added E85 and the percentage was 55% , the boost reached 36 psi
( note : tuner target 2.4 bar around 34 psi )

the injectors duty cycle staring sometimes drop for almost a second at high rpm ( around 5k rpm or 6k rpm ) that’s usually happen on second gear or third gear and sometimes or 5th gear as well
I was checking the log by my self and I noted that’s :

The inj duty cycle is not max out ( almost 80% or 90% )
And the fuel pressure was perfect 100%

some guys told me May be the clutches cause that’s problem

any idea about the problem mention above

regards

Faisal
 

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The log tells the story. Your car is at full throttle and then AFR goes dead lean at 30:1. STFT adds 15% fuel, but can't correct the problem. You then appear to cut the throttle for some reason. Injector duty cycle exceeds 100% earlier in the run and was at 99% when this issues happened. Fuel pressure was not bad so you just need bigger injectors.

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Discussion Starter · #3 ·
The log tells the story. Your car is at full throttle and then AFR goes dead lean at 30:1. STFT adds 15% fuel, but can't correct the problem. You then appear to cut the throttle for some reason. Injector duty cycle exceeds 100% earlier in the run and was at 99% when this issues happened. Fuel pressure was not bad so you just need bigger injectors.

View attachment 403012
Thanks a lot for your feed back
So the fuel pressure is okay that’s mean fuel pumps was okay
And it’s not related to clutchs ?? Am I right !!


just injectors was max out

how about the over boost ? When I read the logs , the boost was reaching 38 and the the tuner target was 34 (2.4), will that’s possible to cut ?
 

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Thanks a lot for your feed back
So the fuel pressure is okay that’s mean fuel pumps was okay
And it’s not related to clutchs ?? Am I right !!


just injectors was max out

how about the over boost ? When I read the logs , the boost was reaching 38 and the the tuner target was 34 (2.4), will that’s possible to cut ?
The first thing I checked was the fuel pressure, which you can look to see if the "Fuel Pressure (relative)" stays somewhat the same value or you can just watch the "Fuel Line Gauge Pressure" and see if it is holding under boost. Prior to the AFR running lean the fuel pressure is holding although I do see a spike in the fuel pressure just before the lean issue happens. I have to assume the data in your log is accurate because I need to track the events chronologically. From the log, the first thing that happens is the AFR runs lean with no contributing factor from Fuel Pressure. It could be there is a delay in how the data was acquired, but I don't know.

The only thing that has me troubled about the fuel pressure is that after AFR runs lean initially while fuel pressure is still good, I see the fuel pressure drop below the 1:1 relationship that should occur. So when boost dropped from 37psi to 25psi (-12psi) then fuel pressure should only drop from 87psi to 75psi (-12psi), but you can see from what I circled below it drops below 60psi. Looking at the log chronologically, the fuel pressure didn't cause the lean condition, but there very well may be a fuel pressure issue contributing to your problem based on what I see below. Definitely with your injectors seeing 100%+ duty cycle they need to be upgraded.

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Regarding the boost target, the log shows the boost target to be 50psi so if that is an accurate log parameter the tuner essentially has the turbos at Max boost.
 

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Discussion Starter · #5 ·
The first thing I checked was the fuel pressure, which you can look to see if the "Fuel Pressure (relative)" stays somewhat the same value or you can just watch the "Fuel Line Gauge Pressure" and see if it is holding under boost. Prior to the AFR running lean the fuel pressure is holding although I do see a spike in the fuel pressure just before the lean issue happens. I have to assume the data in your log is accurate because I need to track the events chronologically. From the log, the first thing that happens is the AFR runs lean with no contributing factor from Fuel Pressure. It could be there is a delay in how the data was acquired, but I don't know.

The only thing that has me troubled about the fuel pressure is that after AFR runs lean initially while fuel pressure is still good, I see the fuel pressure drop below the 1:1 relationship that should occur. So when boost dropped from 37psi to 25psi (-12psi) then fuel pressure should only drop from 87psi to 75psi (-12psi), but you can see from what I circled below it drops below 60psi. Looking at the log chronologically, the fuel pressure didn't cause the lean condition, but there very well may be a fuel pressure issue contributing to your problem based on what I see below. Definitely with your injectors seeing 100%+ duty cycle they need to be upgraded.

View attachment 403023


Regarding the boost target, the log shows the boost target to be 50psi so if that is an accurate log parameter the tuner essentially has the turbos at Max boost.
great

I will try to upgrade the injectors as first solution

do I need to tune after upgrade the injectors

regards
 

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great

I will try to upgrade the injectors as first solution

do I need to tune after upgrade the injectors

regards
yes, tune needs to be setup for larger injectors, but you may very well have a fuel pressure issue.
 
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Discussion Starter · #7 ·
yes, tune needs to be setup for larger injectors, but you may very well have a fuel pressure issue.
Thanks lot for your feed back
I was trying to check it also with my self trying to learn about parameters 😀

I Found also the injectors duty goes 104%

So probably I will go first with injectors upgrade
 

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Thanks lot for your feed back
I was trying to check it also with my self trying to learn about parameters 😀

I Found also the injectors duty goes 104%

So probably I will go first with injectors upgrade
Yea, I noted earlier it exceeded 100%. Just be careful afterwards because of the potential pressure drop. Perhaps have your tuner setup the fail safe for when relative pressure drops below a certain threshold.
 

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Discussion Starter · #9 ·
Yea, I noted earlier it exceeded 100%. Just be careful afterwards because of the potential pressure drop. Perhaps have your tuner setup the fail safe for when relative pressure drops below a certain threshold.
Yeah you are right , the car go for fail safe when the pressure is drop

I am gona place my order in bigger injectors ID1700

And I am in between for choosing the fuel pump :

Should I go with fore invotation triple pump
Or I go with brushless

And I guess I have to add the fuel regulator to that setup am I right
 

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Yeah you are right , the car go for fail safe when the pressure is drop

I am gona place my order in bigger injectors ID1700

And I am in between for choosing the fuel pump :

Should I go with fore invotation triple pump
Or I go with brushless

And I guess I have to add the fuel regulator to that setup am I right
Or upgrade to the JV triple pump option.
 

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I think OEM fuel lines should be ok.
Your Visconti fuel pump setup with hardwire should be OK granted that they are the largest pumps and not the small ones. Think there are 2 or 3 options in pump sizes.
 

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Yeah you are right , the car go for fail safe when the pressure is drop

I am gona place my order in bigger injectors ID1700

And I am in between for choosing the fuel pump :

Should I go with fore invotation triple pump
Or I go with brushless

And I guess I have to add the fuel regulator to that setup am I right
My only warning, most cars setup with 1700cc injectors idle rich because the injector floor is not removed from within the tune. The injector floor will be defined as the Minimum injector pulsewidth and is the least amount of time the injector can be opened. I run FIC 1650cc injectors in the EVO and they idle just fine at 14.7AFR (currently set to 13.5:1 due to cams) based on ~1.24ms IPW. These injectors don't enter the non linear IPW until below 1ms so there should be no issue getting them to idle at stoich on the GTR if stock cams. Just have your tuner set the IPW to whatever the injector manufacturer defines, but it will likely be below 1ms. In Cobb, if you setup the IPW based on how they tell you it won't work correctly.
 
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