changed in jectors what has to be tuned?
Thread Starter
Joined: Mar 2003
Posts: 8,319
Likes: 1
From: North Carolina
changed injectors what has to be tuned? car runs like **** at idle. i changed the IRF table and made one VE change. what else do i need to do? idle o2 sensrs arent oscillating like they used to either and the idle tends to get shitty when the o2s stay at the rich reading and then th estft's dip down. what gives?
Last edited by WS6FirebirdTA00; Mar 22, 2005 at 06:25 PM.
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TECH Apprentice
Joined: Jan 2003
Posts: 308
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From: Mission Viejo CA
To start with your not giving enough info, what injectors did you install and what settings did you put them at? For example if you installed 30# you will need to tell the car that they are 34# due to the higher fuel pressure of our system and what the rating is on the injector. They may think they were suppose to be at 45# fuel pressure when actually you are at 58#. If your still rich then you need to keep upping them till you LTFT come into line. That number may be different for each car.
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Verdad Gallardo Thread Starter
Joined: Mar 2003
Posts: 8,319
Likes: 1
From: North Carolina
yeah its the stock cam, and yes i am maf less and i have been during this whole tuning process and the only change where idle diped like that was the injectors. ]
what im wondering abuot is the o2 oscillation, look how it was before compaired to now. i wonder if the car just needs some more tuning and tweaking to the VE table to get it to idle right??
what im wondering abuot is the o2 oscillation, look how it was before compaired to now. i wonder if the car just needs some more tuning and tweaking to the VE table to get it to idle right??
Thread Starter
Joined: Mar 2003
Posts: 8,319
Likes: 1
From: North Carolina
Originally Posted by Honez
To start with your not giving enough info, what injectors did you install and what settings did you put them at? For example if you installed 30# you will need to tell the car that they are 34# due to the higher fuel pressure of our system and what the rating is on the injector. They may think they were suppose to be at 45# fuel pressure when actually you are at 58#. If your still rich then you need to keep upping them till you LTFT come into line. That number may be different for each car.
i have racetronix 38# injectors. i have a cam and heads going in soon that is why i went for larger ones. i have an excel sheet where it calculates this all out, they are rated at 43.65# for 58 psi and i actually recorded rail pressure for certain vacuum and put that in the computer so it knows the exact flow. need any more info i can put it up
I see, your O2's just slowed down.
I can't say I know why for sure, but I would guess you may be running richer than your LTFTs are indicating, and that may be affecting your O2's.
Do the negative LTFTs build higher the longer you run it? Or are they stabilized when you took that shot?
I can't say I know why for sure, but I would guess you may be running richer than your LTFTs are indicating, and that may be affecting your O2's.
Do the negative LTFTs build higher the longer you run it? Or are they stabilized when you took that shot?
Try going leaner by upping your IFR numbers even more, like 5% or more.
You're going to have to find a point where something either makes it worse or better, and I'm betting there's just too much fuel still.
those are huge injectors to be running on a stock engine, so you may need to back the fuel off more than you thought.
You're going to have to find a point where something either makes it worse or better, and I'm betting there's just too much fuel still.
those are huge injectors to be running on a stock engine, so you may need to back the fuel off more than you thought.
TECH Apprentice
Joined: Jan 2003
Posts: 308
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From: Mission Viejo CA
Okay, the bigger you go the harder it is to get them to idle smoothly. What are your LTFT's at Idle? If the car is running rich and poorly then keep upping them unitl you smooth out and lean that pig down so that your LTFT's are -2 to -5 or so. I personally think you overshoot the size you needed but that's not importiant at this time. Work them up until your happy but not lean at cruse.
Thread Starter
Joined: Mar 2003
Posts: 8,319
Likes: 1
From: North Carolina
they ltft's started out more negative then they went closer to 0 then they went back negative but not as much as the first time and then they went closer to zero but more negative than the previous rebound to 0, just makes me wonder if i need more VE tuning, but like i said the o2 sensors being like that is really throwing me off.
i read in the hp tuners help that the idle base vs airflow mode is directly related to injector size, but i tried to ask magnus about it and havent heard back on how that would have to be changed and it said that it woudl effect the idle also
i read in the hp tuners help that the idle base vs airflow mode is directly related to injector size, but i tried to ask magnus about it and havent heard back on how that would have to be changed and it said that it woudl effect the idle also
Thread Starter
Joined: Mar 2003
Posts: 8,319
Likes: 1
From: North Carolina
from hp tuners help file:
Closed Loop Proportional Base vs. Airflow Mode: This table returns the base proportional % fuel change. Proportional base rate table is the primary amount of fuel needed to drive the closed loop fuel control into oscillation. Proportional fuel acts like an on/off switch to keep the fuel moving around the current O2 Rich/Lean vs. Mode table set point. The values on the Proportional Table add or subtract to the base fuel rate depending on the previous fuel condition (i.e. if rich then switch lean, if lean the switch rich). The amount of fuel to add or subtract increases with the airflow mode and should be based on injector size and % fuel switching needed.
Closed Loop Proportional Gain vs. O2 Error: This table returns a multiplier value for the increase/decrease of the base rate table. A multiplier value of 1.000 will have no effect on the proportional base rate. If the difference between the current O2 reading and its desired value from table O2 Rich/Lean vs Mode (the current Fast O2 error) is large the VCM will need to change the proportional fuel a lot. If the error is small, it should change it only a little to continue oscillation without undershoot or overshoot. Undershooting will cause the Closed loop fuel to become sluggish or miss the current O2 Rich/Lean vs. Mode table set point. Overshooting with cause the engine to vary excessively in RPM.
Closed Loop Proportional Base vs. Airflow Mode: This table returns the base proportional % fuel change. Proportional base rate table is the primary amount of fuel needed to drive the closed loop fuel control into oscillation. Proportional fuel acts like an on/off switch to keep the fuel moving around the current O2 Rich/Lean vs. Mode table set point. The values on the Proportional Table add or subtract to the base fuel rate depending on the previous fuel condition (i.e. if rich then switch lean, if lean the switch rich). The amount of fuel to add or subtract increases with the airflow mode and should be based on injector size and % fuel switching needed.
Closed Loop Proportional Gain vs. O2 Error: This table returns a multiplier value for the increase/decrease of the base rate table. A multiplier value of 1.000 will have no effect on the proportional base rate. If the difference between the current O2 reading and its desired value from table O2 Rich/Lean vs Mode (the current Fast O2 error) is large the VCM will need to change the proportional fuel a lot. If the error is small, it should change it only a little to continue oscillation without undershoot or overshoot. Undershooting will cause the Closed loop fuel to become sluggish or miss the current O2 Rich/Lean vs. Mode table set point. Overshooting with cause the engine to vary excessively in RPM.
Thread Starter
Joined: Mar 2003
Posts: 8,319
Likes: 1
From: North Carolina
i mean that stuff from hp tuners shows my problem, its like the wrote it for me lol but i dont know how to change that stuff, when i went out there before to change it it got worse and worse and worse, idle went 300-900, the idle was oscillating like the o2s do
Originally Posted by WS6FirebirdTA00
Closed Loop Proportional Gain vs. O2 Error: This table returns a multiplier value for the increase/decrease of the base rate table. A multiplier value of 1.000 will have no effect on the proportional base rate. If the difference between the current O2 reading and its desired value from table O2 Rich/Lean vs Mode (the current Fast O2 error) is large the VCM will need to change the proportional fuel a lot. If the error is small, it should change it only a little to continue oscillation without undershoot or overshoot. Undershooting will cause the Closed loop fuel to become sluggish or miss the current O2 Rich/Lean vs. Mode table set point. Overshooting with cause the engine to vary excessively in RPM.
I'm sure some other people have adjusted this after an injector change and hopefully they see this and add their input. I'd like to hear more about this too since my version of Edit doesn't show this.
Originally Posted by WS6FirebirdTA00
im gonna give this all a shot tomorrow when i get out of class. so if its over shooting would you assume to decrease this multiplier??
