Injector Bias (added)
#3
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#7
OK, i think i see what this injector bias is. Looking at the pulse width at the injector with an oscilloscope, there is a spike right at the begining of the pulse width, its very slight, but its there. I see how that would help the injector firing at low Pulse widths.
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#8
OK, i think i see what this injector bias is. Looking at the pulse width at the injector with an oscilloscope, there is a spike right at the begining of the pulse width, its very slight, but its there. I see how that would help the injector firing at low Pulse widths.
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Does anybody know if the reported PW in a datalog is the calculated or the actual? Also does anybody know how to tell if it is off? The reason for my question is all injectors are different so if you put in a different set with a different rate how do you calibrate this?
#12
Does anybody know if the reported PW in a datalog is the calculated or the actual? Also does anybody know how to tell if it is off? The reason for my question is all injectors are different so if you put in a different set with a different rate how do you calibrate this?
#13
You know, i was thinking. The 305,350 bins are set to 396.50 (Injector Bias), 454 is set to 274, and the 6 cylinders are set to 480. these times are in microseconds. If i set my injector bias up (like 520) i get a rich smell. The engine seems to run a little smoother to. If what is explained is true, then Pulse widths at larger duration would be extended to. Since im a taqd lean in the upper r's being at 100% VE, then more bias should help there.
#14
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The spike you are seeing is the "peak" portion of a "peak and hold" injector pulse. This is a hardware function and has nothing to do with injector bias. The reason for the bias is because the injector requires a set amount of time to open to the point where fuel flows. This time can be as short as a few hundred microseconds for a TBI injector to over one millisecond for a saturated port injector. Say for examplethe ECM calculated that on a port injected setup, it requires a 1.5mS pulse width. Since it takes 1mS for the injector to open, fuel will only flow for .5mS or only 1/3 of what is needed. If a bias of 1mS is added to the final pulse width, a 2.5mS pulse occurs minus the 1mS for the injector to open and fuel flows for 1.5mS. Just what the ECM commanded. Make sense?
Escort,
If you re-read Haulin's post you'll understand why more bias causes a richer mixture.
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Re: Injector Bias (added)
I know this post is a little old, but is there a way to tell what the correct amount should be? Do you just adjust up or down until the idle is smoother?
I guess I understand what it does, I just don't understand how to properly set it.
I guess I understand what it does, I just don't understand how to properly set it.
#16
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Re: Injector Bias (added)
I don't think you do understand. You don't use the IB for setting a smoother idle. Lowering the IB will generally cause a leaning of the mixture and vice versa.
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Re: Injector Bias (added)
I understand it isn't for making the idle smoother, but I'm not seeing any other way to tell if the bias is set too little or too much. If the bias tends to lean or richen the mixture, how do you find the proper amount of bias?
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#20
Re: Injector Bias (added)
ive been messing with this myself. not sure if its doing much for me. from what ive read, the way to tell if you need to raise the bias is by looking at the ve tables in the low map areas where your p.w. are generally at ther lowest. if you are needing to raise your ve higher in those areas creating an upside down bathtub shape on the graph, you may need to raise your bias. the bias allows for the injector opening time. if you have raised your fuel pressure the injector probably needs more time to open. this would be a reason to play with the bias. i have 65lb injectors at 24psi and have my bias set at .656 usec right now. my idle p.w. are about about .8-1.0ms. im struggling more with surging at low map under light throttle deceleration. my afr's are swinging 12.0-16.0. lowering prop gains and prop counts havent helped enough yet.
#21
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Re: Injector Bias (added)
The best way is to simply set the IB at a level that matches the injector opening interval. With TB injectors its around 700msec. Then tune from there.
getsideways,
Lower the Prop Gains further. You'd be surprised at how little PG you need with 24 psi particularly in the 0 -16 gm/sec airflow area.
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Re: Injector Bias (added)
The best way is to simply set the IB at a level that matches the injector opening interval. With TB injectors its around 700msec. Then tune from there.
getsideways,
Lower the Prop Gains further. You'd be surprised at how little PG you need with 24 psi particularly in the 0 -16 gm/sec airflow area.
getsideways,
Lower the Prop Gains further. You'd be surprised at how little PG you need with 24 psi particularly in the 0 -16 gm/sec airflow area.
If you were running SVO 30's in a Miniram at approx 48PSI, what would you use for the INB?
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