Minimum Pulse Width
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Launching!
Joined: Dec 2001
Posts: 250
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From: Albuquerque, New Mexico
Minimum Pulse Width I am wondering about injectors being too large for an engine. Does anyone know how small a pulse width you can go to and still be able to tune for a decent idle? I have heard that 2.5 ms might be the bottom limit. I am speaking of the high impedance injectors.
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From: College Station, Tx
Re: Minimum Pulse Width There is a minimum pulsewidth - I think harlan ran into that issue? You can simply set your car into open loop at idle and you should be fine though (and leave it in closed loop for the rest of operation). You may run a tad richer at idle, but it won't give you any big problems (unless you need to pass a sniffer).
55's should be fine though - it is when you get up to the 7x area that you start having this problem.
55's should be fine though - it is when you get up to the 7x area that you start having this problem.
Thread Starter
Launching!
Joined: Dec 2001
Posts: 250
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From: Albuquerque, New Mexico
Re: Minimum Pulse Width Thanks for that info, ChrisB. I assume you mean to use the VE tables for the idle when in open loop. How do you suggest to put it into open loop at idle only with LS1 Edit?
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Joined: Nov 2001
Posts: 3,048
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From: Raleigh, NC
Re: Minimum Pulse Width Though it will sting my eyes if it idles long in the garage, I am running the Hi-Z 55's.
For my setup, 83# Lo-Z and Drivers may have been smarter.
Mine is about 2.9 to 3.2 when it settles out... and anywhere from 1.8 to 2.6 or so when I first crank it up, and it idles OK.
RPM MPH Tmng K/R G/Cy LTF1 LTF2 STF1 IPW1 MAFg MAFf FT MAP AFR
829 0.0 20.5 0.0 0.29 -1.6 -1.6 -0.0 2.93 15.9 2834 20 09.1 14.6
900 0.0 19.0 0.0 0.26 -1.6 -1.6 -0.0 2.93 15.5 2806 20 09.0 14.6
873 0.0 18.0 0.0 0.29 -1.6 -1.6 -0.0 2.81 16.6 2892 20 08.8 14.6
895 0.0 18.5 0.0 0.26 -1.6 -1.6 -0.8 2.87 15.3 2788 20 08.8 14.6
879 0.0 18.0 0.0 0.27 -1.6 -1.6 -0.8 2.78 15.8 2833 20 08.8 14.6
856 0.0 18.0 0.0 0.31 -1.6 -1.6 -0.8 2.85 18.0 2991 20 09.0 14.6
848 0.0 25.5 0.0 0.31 -1.6 -1.6 -1.6 2.93 17.6 2963 20 09.1 14.6
824 0.0 25.5 0.0 0.32 -1.6 -1.6 -1.6 3.08 17.6 2961 20 09.3 14.6
772 0.0 25.5 0.0 0.34 -1.6 -1.6 -1.6 3.19 17.4 2944 20 09.7 14.6
724 0.0 26.0 0.0 0.36 -1.6 -1.6 -1.6 3.25 17.1 2929 20 10.0 14.6
688 0.0 26.5 0.0 0.35 -1.6 -1.6 -1.6 3.42 16.2 2859 20 10.3 14.6
655 0.0 27.0 0.0 0.37 -1.6 -1.6 -1.6 3.66 16.0 2846 20 11.0 14.6
698 0.0 27.0 0.0 0.34 -1.6 -1.6 -2.3 3.59 15.6 2815 20 10.7 14.6
761 0.0 30.0 0.0 0.34 -1.6 -1.6 -2.3 3.43 17.1 2928 20 10.6 14.6
851 0.0 25.0 0.0 0.29 -1.6 -1.6 -2.3 3.19 16.6 2888 20 10.0 14.6
927 0.0 23.0 0.0 0.28 -1.6 -1.6 -3.1 3.05 17.6 2960 20 09.7 14.6
886 0.0 24.0 0.0 0.30 -1.6 -1.6 -3.1 3.02 17.5 2952 20 09.4 14.6
856 0.0 26.0 0.0 0.31 -1.6 -1.6 -3.1 3.02 17.6 2966 20 09.7 14.6
823 0.0 26.5 0.0 0.32 -1.6 -1.6 -3.1 3.05 17.7 2971 20 09.9 14.6
794 0.0 29.5 0.0 0.32 -1.6 -1.6 -3.1 3.16 16.8 2903 20 10.0 14.6
For my setup, 83# Lo-Z and Drivers may have been smarter.
Mine is about 2.9 to 3.2 when it settles out... and anywhere from 1.8 to 2.6 or so when I first crank it up, and it idles OK.
RPM MPH Tmng K/R G/Cy LTF1 LTF2 STF1 IPW1 MAFg MAFf FT MAP AFR
829 0.0 20.5 0.0 0.29 -1.6 -1.6 -0.0 2.93 15.9 2834 20 09.1 14.6
900 0.0 19.0 0.0 0.26 -1.6 -1.6 -0.0 2.93 15.5 2806 20 09.0 14.6
873 0.0 18.0 0.0 0.29 -1.6 -1.6 -0.0 2.81 16.6 2892 20 08.8 14.6
895 0.0 18.5 0.0 0.26 -1.6 -1.6 -0.8 2.87 15.3 2788 20 08.8 14.6
879 0.0 18.0 0.0 0.27 -1.6 -1.6 -0.8 2.78 15.8 2833 20 08.8 14.6
856 0.0 18.0 0.0 0.31 -1.6 -1.6 -0.8 2.85 18.0 2991 20 09.0 14.6
848 0.0 25.5 0.0 0.31 -1.6 -1.6 -1.6 2.93 17.6 2963 20 09.1 14.6
824 0.0 25.5 0.0 0.32 -1.6 -1.6 -1.6 3.08 17.6 2961 20 09.3 14.6
772 0.0 25.5 0.0 0.34 -1.6 -1.6 -1.6 3.19 17.4 2944 20 09.7 14.6
724 0.0 26.0 0.0 0.36 -1.6 -1.6 -1.6 3.25 17.1 2929 20 10.0 14.6
688 0.0 26.5 0.0 0.35 -1.6 -1.6 -1.6 3.42 16.2 2859 20 10.3 14.6
655 0.0 27.0 0.0 0.37 -1.6 -1.6 -1.6 3.66 16.0 2846 20 11.0 14.6
698 0.0 27.0 0.0 0.34 -1.6 -1.6 -2.3 3.59 15.6 2815 20 10.7 14.6
761 0.0 30.0 0.0 0.34 -1.6 -1.6 -2.3 3.43 17.1 2928 20 10.6 14.6
851 0.0 25.0 0.0 0.29 -1.6 -1.6 -2.3 3.19 16.6 2888 20 10.0 14.6
927 0.0 23.0 0.0 0.28 -1.6 -1.6 -3.1 3.05 17.6 2960 20 09.7 14.6
886 0.0 24.0 0.0 0.30 -1.6 -1.6 -3.1 3.02 17.5 2952 20 09.4 14.6
856 0.0 26.0 0.0 0.31 -1.6 -1.6 -3.1 3.02 17.6 2966 20 09.7 14.6
823 0.0 26.5 0.0 0.32 -1.6 -1.6 -3.1 3.05 17.7 2971 20 09.9 14.6
794 0.0 29.5 0.0 0.32 -1.6 -1.6 -3.1 3.16 16.8 2903 20 10.0 14.6
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From: College Station, Tx
Re: Minimum Pulse Width You can set the TPS to Enable WOT/PE to 0% for 0-1600 or so. This will put you in PE mode at all times in that rpm range, and so O2 feedback will be ignored. As soon as you cross whatever the top RPM threshold was you used O2's will kick back in.
You can then tune the fuel at idle in whatever manner you chose (I used the PE table when doing that - 0-1600 or whatever your top RPM was).
You can then tune the fuel at idle in whatever manner you chose (I used the PE table when doing that - 0-1600 or whatever your top RPM was).
