High or low impedence injectors?
05-16-2005, 09:25 PM
#1
High or low impedence injectors? I know this is posted in the wrong area but I need a quick reply. I am looking into purchasing a set of 42lbs injectors for my LS1 but can someone explain the diffrence between high and low impedance, and is there a way to tell on the injector. Also I was wondering if these would support my future mods. Im hoping for 550 rwhp with 10-12lbs boost (d1sc) mild cam tr224, 114, and maybe a mild port on the stock heads. Keeping the compression between 9.5'\i./10.0 to 1 not sure which yet. Should I move to larger ones or should these be enough. thanks guys.
05-17-2005, 10:27 AM
#3
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Your injector driver is set up to run high impedence/saturated injectors. It will not support low impedence/ peak and hold injectors unless you splice in an aftermarket driver.
Stick with high impedence.
Typically low ohm injectors have better control throughout the pulsewidth range and less variability with changes to voltage. The typical set up is 4 amp to peak (or open) and 1 amp to keep open throughout injector pulse. Power is supplied directly from the battery/alternator. In short, they are better but cost more.
Stick with high impedence.
Typically low ohm injectors have better control throughout the pulsewidth range and less variability with changes to voltage. The typical set up is 4 amp to peak (or open) and 1 amp to keep open throughout injector pulse. Power is supplied directly from the battery/alternator. In short, they are better but cost more.
Last edited by SSpeedracer; 05-17-2005 at 12:13 PM.
05-17-2005, 10:49 AM
#4
Originally Posted by SSpeedracer
Your injector driver is set up to run high impedence/saturated injectors. It will support low impedence/ peak and hold injectors unless you splice in an aftermarket driver.
Stick with high impedence.
Typically low ohm injectors have better control throughout the pulsewidth range and less variability with changes to voltage. The typical set up is 4 amp to peak (or open) and 1 amp to keep open throughout injector pulse. Power is supplied directly from the battery/alternator. In short, they are better but cost more.
Stick with high impedence.
Typically low ohm injectors have better control throughout the pulsewidth range and less variability with changes to voltage. The typical set up is 4 amp to peak (or open) and 1 amp to keep open throughout injector pulse. Power is supplied directly from the battery/alternator. In short, they are better but cost more.
05-17-2005, 12:47 PM
#5
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I've read your plight in the other threads.
Every injector from each manufacturer has a different linear flow range and working flow range. The LFR/WFR is usefull when calibrating the PCM to control flow rate relative to pulse width. Like yourself, I am learning how to retune the VCM, so I cant give you much help there. Your new injectors have a different LFR and that can easily be tuned as you have done. However, the WFR is another story. I dont know how or if the VCM takes into account WFR. If an injector has a minimum flow rate, and the VCM is commanding less than that forget it, nothing to do. If this is your problem, is sounds like just one or two of your injectors are not firing which is likely due to injector tolerance differences.
If I recall, the vcm controls injectors based on voltage also. Saturated (or high impedance) injectors are notorious for fluctuating or dropping out if supply voltage drops. A long shot might be raising the voltage offsets
If I were you, I would swap back the OEM injectors and confirm the system works. Then swap in a set of 42# injectors and be done with it. I havent come accross a negative post with the 42#.
If you are dead set on keeping the 38# try raising your idle and determine how much bigger a pulse width is required to elimiate an injector misfire. Does the scanner measure which cylinder has the misfire? If yes, log it then switch injectors and see if you have a failing injector.
Your statement that misfires occur under light throttle leads me to think you've got another issue, not WFR for 38#'s. Sounds more like a bad injector or bad injector driver on that circuit.
Every injector from each manufacturer has a different linear flow range and working flow range. The LFR/WFR is usefull when calibrating the PCM to control flow rate relative to pulse width. Like yourself, I am learning how to retune the VCM, so I cant give you much help there. Your new injectors have a different LFR and that can easily be tuned as you have done. However, the WFR is another story. I dont know how or if the VCM takes into account WFR. If an injector has a minimum flow rate, and the VCM is commanding less than that forget it, nothing to do. If this is your problem, is sounds like just one or two of your injectors are not firing which is likely due to injector tolerance differences.
If I recall, the vcm controls injectors based on voltage also. Saturated (or high impedance) injectors are notorious for fluctuating or dropping out if supply voltage drops. A long shot might be raising the voltage offsets
If I were you, I would swap back the OEM injectors and confirm the system works. Then swap in a set of 42# injectors and be done with it. I havent come accross a negative post with the 42#.
If you are dead set on keeping the 38# try raising your idle and determine how much bigger a pulse width is required to elimiate an injector misfire. Does the scanner measure which cylinder has the misfire? If yes, log it then switch injectors and see if you have a failing injector.
Your statement that misfires occur under light throttle leads me to think you've got another issue, not WFR for 38#'s. Sounds more like a bad injector or bad injector driver on that circuit.
05-17-2005, 02:31 PM
#6
Originally Posted by SSpeedracer
I've read your plight in the other threads.
Every injector from each manufacturer has a different linear flow range and working flow range. The LFR/WFR is usefull when calibrating the PCM to control flow rate relative to pulse width. Like yourself, I am learning how to retune the VCM, so I cant give you much help there. Your new injectors have a different LFR and that can easily be tuned as you have done. However, the WFR is another story. I dont know how or if the VCM takes into account WFR. If an injector has a minimum flow rate, and the VCM is commanding less than that forget it, nothing to do. If this is your problem, is sounds like just one or two of your injectors are not firing which is likely due to injector tolerance differences.
If I recall, the vcm controls injectors based on voltage also. Saturated (or high impedance) injectors are notorious for fluctuating or dropping out if supply voltage drops. A long shot might be raising the voltage offsets
If I were you, I would swap back the OEM injectors and confirm the system works. Then swap in a set of 42# injectors and be done with it. I havent come accross a negative post with the 42#.
If you are dead set on keeping the 38# try raising your idle and determine how much bigger a pulse width is required to elimiate an injector misfire. Does the scanner measure which cylinder has the misfire? If yes, log it then switch injectors and see if you have a failing injector.
Your statement that misfires occur under light throttle leads me to think you've got another issue, not WFR for 38#'s. Sounds more like a bad injector or bad injector driver on that circuit.
Every injector from each manufacturer has a different linear flow range and working flow range. The LFR/WFR is usefull when calibrating the PCM to control flow rate relative to pulse width. Like yourself, I am learning how to retune the VCM, so I cant give you much help there. Your new injectors have a different LFR and that can easily be tuned as you have done. However, the WFR is another story. I dont know how or if the VCM takes into account WFR. If an injector has a minimum flow rate, and the VCM is commanding less than that forget it, nothing to do. If this is your problem, is sounds like just one or two of your injectors are not firing which is likely due to injector tolerance differences.
If I recall, the vcm controls injectors based on voltage also. Saturated (or high impedance) injectors are notorious for fluctuating or dropping out if supply voltage drops. A long shot might be raising the voltage offsets
If I were you, I would swap back the OEM injectors and confirm the system works. Then swap in a set of 42# injectors and be done with it. I havent come accross a negative post with the 42#.
If you are dead set on keeping the 38# try raising your idle and determine how much bigger a pulse width is required to elimiate an injector misfire. Does the scanner measure which cylinder has the misfire? If yes, log it then switch injectors and see if you have a failing injector.
Your statement that misfires occur under light throttle leads me to think you've got another issue, not WFR for 38#'s. Sounds more like a bad injector or bad injector driver on that circuit.
