LS1-edit Tuning Suggestions
04-12-2003, 06:59 AM
#2
Moderator
Re: LS1-edit Tuning Suggestions My2Cents:
Injector Flow Rate Table
Normally, use your Injector Flow Rate (IFR) Table to adjust LTFT's.
Adjust IFR's downward to decrease LTFT (tells the computer the injector is smaller than what it now believes it is, so more fuel is added, which compensates for what the computer believes is a lean condition based on O2 Sensor readings, and brings the LTFT adjustment more negative).
Adjust IFR's upward to increase LTFT (opposite of what I said for adjusting downward).
The intent of the table is to introduce a constant that coincides with the injector size and the Fuel Pressure.
Theoretically, if you haven't changed the injector or changed your Fuel Pressure, you should not modify this table. If your LTFT's are out of whack, you should first look for vacuum leaks and other abnormal situations. However, modding the car can alter the LTFT's, so you may be justified in changing them if there are no problems that would induce a shift.
The logic behind zeroing or negating LTFT's is that when you go WOT, LTFT's will be zeroed, meaning no additional fuel is being dumped into the engine at WOT and tuning will be easier. It has been argued that if you can obtain positive LTFT's of a consistent value, this is just as good, as the value is predictable, and thus tunable. That argument seems to have merit to me. But, it has been my experience that when I make LTFT's zero or slightly negative, my car REALLY wakes up at WOT. It even seems more responsive at part throttle. But that is my experience.
MAF Table
This table calibrates the MAF Sensor and should be left stock if your MAF is stock. Period.
If you get an after-market MAF, in my opinion, they should supply you with or point you to a means of calibrating for it.
LS1-Edit or a MAFT or whatever could do this.
If you port or remove the screen of your MAF sensor, you have changed it (and will likely be running lean as a result of the increased airflow).
Assuming one could port the MAF at home in a consistent way, if LTFT's are positive and MAF related:
Adjust MAF values upward 1% to decrease LTFT's by 1%.
Adjust MAF values downward 1% to increase LTFT's by 1%.
So, if you are +10 on your LTFT's, scale the MAF table by a value of 105 (increases the table values by 10%), which will decrease LTFT's approximately -10. It may take a couple tries.
95 (95% multiplier decreases table values by 5%), which would raise LTFT's +5.
PE/RPM Table
Increasing the Multiplier (the value in each table entry) adds fuel at WOT.
Decreasing the Multiplier subtracts fuel from what the previous value supplied.
This is the table to use to tune your A/F ratio on the dyno (which should decrease or increase O2 Banks 1 and 2 depending on whether you have leaned or richened the mixture, respectively). O2 Bank readings are one of the tools you would use to determine if you are running rich or lean at WOT, relatively speaking, when you are on the track or the street. I've heard that values of 870 to 930 milliVolts (.870 or .930 volts) are a reasonable range for NA cars. For Forced induction, I try for no less than 920 mV; 930 mV is safer, still. There are arguments as to why you CAN'T use the O2 sensors to tune. But, everyone does, if they are not on a dyno... they ARE useful even if they are not terribly accurate from an ABSOLUTE perspective.
The keyword here is RELATIVE. <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />
That's my understanding of basic tuning the A/F Ratio for optimal performance.
Good luck!
Injector Flow Rate Table
Normally, use your Injector Flow Rate (IFR) Table to adjust LTFT's.
Adjust IFR's downward to decrease LTFT (tells the computer the injector is smaller than what it now believes it is, so more fuel is added, which compensates for what the computer believes is a lean condition based on O2 Sensor readings, and brings the LTFT adjustment more negative).
Adjust IFR's upward to increase LTFT (opposite of what I said for adjusting downward).
The intent of the table is to introduce a constant that coincides with the injector size and the Fuel Pressure.
Theoretically, if you haven't changed the injector or changed your Fuel Pressure, you should not modify this table. If your LTFT's are out of whack, you should first look for vacuum leaks and other abnormal situations. However, modding the car can alter the LTFT's, so you may be justified in changing them if there are no problems that would induce a shift.
The logic behind zeroing or negating LTFT's is that when you go WOT, LTFT's will be zeroed, meaning no additional fuel is being dumped into the engine at WOT and tuning will be easier. It has been argued that if you can obtain positive LTFT's of a consistent value, this is just as good, as the value is predictable, and thus tunable. That argument seems to have merit to me. But, it has been my experience that when I make LTFT's zero or slightly negative, my car REALLY wakes up at WOT. It even seems more responsive at part throttle. But that is my experience.
MAF Table
This table calibrates the MAF Sensor and should be left stock if your MAF is stock. Period.
If you get an after-market MAF, in my opinion, they should supply you with or point you to a means of calibrating for it.
LS1-Edit or a MAFT or whatever could do this.
If you port or remove the screen of your MAF sensor, you have changed it (and will likely be running lean as a result of the increased airflow).
Assuming one could port the MAF at home in a consistent way, if LTFT's are positive and MAF related:
Adjust MAF values upward 1% to decrease LTFT's by 1%.
Adjust MAF values downward 1% to increase LTFT's by 1%.
So, if you are +10 on your LTFT's, scale the MAF table by a value of 105 (increases the table values by 10%), which will decrease LTFT's approximately -10. It may take a couple tries.
95 (95% multiplier decreases table values by 5%), which would raise LTFT's +5.
PE/RPM Table
Increasing the Multiplier (the value in each table entry) adds fuel at WOT.
Decreasing the Multiplier subtracts fuel from what the previous value supplied.
This is the table to use to tune your A/F ratio on the dyno (which should decrease or increase O2 Banks 1 and 2 depending on whether you have leaned or richened the mixture, respectively). O2 Bank readings are one of the tools you would use to determine if you are running rich or lean at WOT, relatively speaking, when you are on the track or the street. I've heard that values of 870 to 930 milliVolts (.870 or .930 volts) are a reasonable range for NA cars. For Forced induction, I try for no less than 920 mV; 930 mV is safer, still. There are arguments as to why you CAN'T use the O2 sensors to tune. But, everyone does, if they are not on a dyno... they ARE useful even if they are not terribly accurate from an ABSOLUTE perspective.
The keyword here is RELATIVE. <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />
That's my understanding of basic tuning the A/F Ratio for optimal performance.
Good luck!
04-15-2003, 08:43 PM
#3
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Re: LS1-edit Tuning Suggestions Just wanted to post to let you know how well you did with your description... <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" /> You make it seem so easy! Thanks.
We are so blessed to have the LS1 operating system.
Poor Stang guys are always trying different "chips"... Mail one....wait for another..etc. What a racket.
We are so blessed to have the LS1 operating system.
Poor Stang guys are always trying different "chips"... Mail one....wait for another..etc. What a racket.
04-15-2003, 10:38 PM
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Re: LS1-edit Tuning Suggestions Black > good post. I've read a lot about how dyno tuning is not the way to go, but others say it is. Personally, I am about to go to the dyno and tune my car (got LS1edit a week ago - and am having a blast with it), but I will save the $100 if I can just use my O2s.
I've heard about the O2s not reading correctly at WOT, but mine seem to give values that are reasonable (about 930 at WOT). On the dyno a couple months ago, I had 11:1 A/F...so I obviously need to lean it out (assuming the dyno is remotely accurate...and I think it is - brand new wideband). This also jived with my previous A/F of low 11s.
Anyway, can I tune WOT A/F using O2?
Should I tune Timing before WOT A/F?
I've heard about the O2s not reading correctly at WOT, but mine seem to give values that are reasonable (about 930 at WOT). On the dyno a couple months ago, I had 11:1 A/F...so I obviously need to lean it out (assuming the dyno is remotely accurate...and I think it is - brand new wideband). This also jived with my previous A/F of low 11s.
Anyway, can I tune WOT A/F using O2?
Should I tune Timing before WOT A/F?
