High fuel table value Modelled but low injector Duty

[Iguanapeluda]

Hi!, 

I have tuned my Lancer evo IX with 2150cc injectors, HKS 7460 Kai turbo, and i have a due...I have very high value of fuel table ( I have zones with 130 of value, but the duty is 30-40%...). Why not a 100% of duty correspond with 150 of fuel table value? I attach my configuration:

 

 

[essb00]

During a combustion cycle (720°), the injector is open for a % of the total cycle time. That's referred to as injector duty cycle. 
Injector duty cycle is affected by engine speed - where an injector pulse width will appear as high duty cycle at higher rpm.

You actually don't want to get higher than 80% injector duty cycle - as it would mean your injector would almost not close.

[ellisd1984]

The table you're filling in is the % of air.  The ecu then uses all the numbers you've inputted such as injector size, fuel pressure, deadtime etc to calculate the required DC% to get you the target afr you've asked for.  So the numbers in the fuel table (not sure fuel table is actually the correct terminology since the numbers aren't actually fuel) aren't directly linked to injector DC as by changing say "injector size" to 1000cc would mean the injector DC% would increase because even though you've left the main table alone the ecu would calculate the injectors are half the size so would need to increase the DC% to compensate to get you the same afr.

Least thats my Understanding of it
 

[0x33]

Before considering what your injector duty is doing, consider what your fuel map looks like. Modelled mode is meant to model airflow based on VE. Your numbers in your VE table make no sense. I've yet to come across any engine that is only 20% efficient on idle, typically this value is around 50-70 depending on cams etc. 

 

You have one of the following things going on:

- Mechnical issue like bad fuel pressure, intake system leak, bad injectors, bad lambda sensor etc.

- Tuning issue like: Incorrect injector data, engine data, charge temp correction, sensor calibrations etc. 

Below is the variables that the ECU uses to calculate fuel delivery with modelled mode. Go through and check all settings. 

In the past when I've had issues like yours its always either been a tuning error on my part or in some cases injectors were shit and didn't play well. 

If all else fails put the ECU back into traditional fueling modeand give it a quick fuel map and see if your scaling is still weird. If it is then probably a mechnical issue. 

[ellisd1984]

Checking the fuel pressure with a mechanical gauge would be a good place to start as mine was well out and htre my numbers out quite a bit

[Iguanapeluda]

8 hours ago, 0x33 said:

Before considering what your injector duty is doing, consider what your fuel map looks like. Modelled mode is meant to model airflow based on VE. Your numbers in your VE table make no sense. I've yet to come across any engine that is only 20% efficient on idle, typically this value is around 50-70 depending on cams etc. 

 

You have one of the following things going on:

- Mechnical issue like bad fuel pressure, intake system leak, bad injectors, bad lambda sensor etc.

- Tuning issue like: Incorrect injector data, engine data, charge temp correction, sensor calibrations etc. 

Below is the variables that the ECU uses to calculate fuel delivery with modelled mode. Go through and check all settings. 

In the past when I've had issues like yours its always either been a tuning error on my part or in some cases injectors were shit and didn't play well. 

If all else fails put the ECU back into traditional fueling modeand give it a quick fuel map and see if your scaling is still weird. If it is then probably a mechnical issue. 

Yes, I have made another lancer EVO 8 with 1000cc injectors and G5-660 injectors, and at idle more or less is around 50-60 of fuel table, and a maximum of 100 of table "VE" for 85-88% of DUTY CICLE teorical.

6 hours ago, ellisd1984 said:

Checking the fuel pressure with a mechanical gauge would be a good place to start as mine was well out and htre my numbers out quite a bit

Yes, this week I will take a fuel sensor pressure and view if my fuel pressure drop´s!

To reply for the other guy, this is my G4+ NO MODELLED fuel (days ago). In both the calculated Duty is around 40%.

 

[Adamw]

Note as others have said above, in modeled mode the fuel table has nothing to do with injector PW or duty cycle, it is the volumetric efficiency, or in other words it is a measure of the air flow.   

So if you have a value of 100% in the fuel table it means your 2320cc engine will inhale 2320cc of air in one engine cycle.  If you have a VE of 150% it means your 2320cc engine inhaled 3480cc of air in one cycle (obviously impossible).  

Typically in modeled mode you will have a range of numbers from about 50-60% at idle to 100-120 at peak efficiency.  The areas in your VE table where the numbers are 20-40 is probably just because your injectors are working in the non-linear region and you dont have proper characterization data to correct it.  The areas where the VE is un-realistically high is possibly low fuel pressure or incorrect injector flow rate.   

[Iguanapeluda]

10 hours ago, Adamw said:

Note as others have said above, in modeled mode the fuel table has nothing to do with injector PW or duty cycle, it is the volumetric efficiency, or in other words it is a measure of the air flow.   

So if you have a value of 100% in the fuel table it means your 2320cc engine will inhale 2320cc of air in one engine cycle.  If you have a VE of 150% it means your 2320cc engine inhaled 3480cc of air in one cycle (obviously impossible).  

Typically in modeled mode you will have a range of numbers from about 50-60% at idle to 100-120 at peak efficiency.  The areas in your VE table where the numbers are 20-40 is probably just because your injectors are working in the non-linear region and you dont have proper characterization data to correct it.  The areas where the VE is un-realistically high is possibly low fuel pressure or incorrect injector flow rate.   

YeeeeeahhH!!, is exacly, in idle are....my Inyector Dynamics 2150cc, are not very lineal.

My head don´t understood that a 130% of fuel cell not correspond with more or less 80-90% of duty, now if I think in terms of VE efficiency I have understand all!.

 

Thank you again Adam and the rest of the forum.

[Iguanapeluda]

On 2/7/2021 at 7:59 AM, Adamw said:

Note as others have said above, in modeled mode the fuel table has nothing to do with injector PW or duty cycle, it is the volumetric efficiency, or in other words it is a measure of the air flow.   

So if you have a value of 100% in the fuel table it means your 2320cc engine will inhale 2320cc of air in one engine cycle.  If you have a VE of 150% it means your 2320cc engine inhaled 3480cc of air in one cycle (obviously impossible).  

Typically in modeled mode you will have a range of numbers from about 50-60% at idle to 100-120 at peak efficiency.  The areas in your VE table where the numbers are 20-40 is probably just because your injectors are working in the non-linear region and you dont have proper characterization data to correct it.  The areas where the VE is un-realistically high is possibly low fuel pressure or incorrect injector flow rate.   

Yeah Adam, problem solved with my fuel pressure....now the fuel map (VE map) is better: