Injector duty cycle question
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Joined: Apr 2006
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From: Naperville, IL
Injector duty cycle question Tuner was pulling some logs on a highway run, and in 3rd gear.
I have a mild heads/cam car and, currently, stock injectors.
The IDC was at 58% at 3700, 87% at 5000, and 102% at 6000, and the combo makes peak power about 6300.
I will be upgrading to 42's but I wanted to know..
In the meantime, would shifting at 6000 be ok? or am I risking something? 42's seem like the right choice?
I have a mild heads/cam car and, currently, stock injectors.
The IDC was at 58% at 3700, 87% at 5000, and 102% at 6000, and the combo makes peak power about 6300.
I will be upgrading to 42's but I wanted to know..
In the meantime, would shifting at 6000 be ok? or am I risking something? 42's seem like the right choice?
Duty Cycle I never understood how you can control a solenoid (injector coil) to be on longer than 100% duty cycle. Is there some sort of data converison for this number to be 102% in your scan software. It just doesn't seem possible....I have seen this before on this site pertaining to injector duty cycles. Any ideas how this can be?
Not trying to hijack your thread, just curious as to the relation fo these numbers. I have been a driveability tech for over 20 yrs and do not understand this, nor have I ever seen this on any other module controlled solenoid - EGR, EVAP, TCC, etc.
I would think the transistor/driver in the PCM would not like this and eentually get to warm and shut down. Also, I wold think that fuel control would not be as precise at 100% on time for any extended time periods
Not trying to hijack your thread, just curious as to the relation fo these numbers. I have been a driveability tech for over 20 yrs and do not understand this, nor have I ever seen this on any other module controlled solenoid - EGR, EVAP, TCC, etc.
I would think the transistor/driver in the PCM would not like this and eentually get to warm and shut down. Also, I wold think that fuel control would not be as precise at 100% on time for any extended time periods
basically the injector is just at full capacity 80% is the target. That way your fuel system can compensate for variations in humidity & air density. the larger than 100% # is a theoritical number and shows how much injector you are actually lacking. so in theory he needs an injector that is 22% larger. of course that is just theory and it depends on the setup. 
Thread Starter
Banned
Joined: Apr 2006
Posts: 1,875
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From: Naperville, IL
Originally Posted by heavy6.0
basically the injector is just at full capacity 80% is the target. That way your fuel system can compensate for variations in humidity & air density. the larger than 100% # is a theoritical number and shows how much injector you are actually lacking. so in theory he needs an injector that is 22% larger. of course that is just theory and it depends on the setup.
I also would have expected it to get up to around 110% at 6500 where I plan to shift.. we just didn't take it all the way there.
I also did not check the fuel pressure at the rail, nor do I know the AF ratio.. we didn't get it on the dyno. The tune is based off one from a similar setup where the AF was 12.5 to 1 iirc..
I am thinking I will go 42's and have it SD tuned
