BBC, dual gm tbi, MSII, V3,code 2.89
I am going on the bases that my injector opening time is 1ms and my total time is 1.35ms at idle. My idle is pretty stable at this setting. I have read that small open times gives idle problems. From practical experience what minimum open time have others dealt with. I have been fooling with variable fuel pressure system to increase my idle open time but it is a lot of interpolation and trial and error work and would not rather do it if it doesn't appear I will gain from it. With the variable pressure I can get my total open times to 1.67ms. I am presently using 2 squirts sim and tried alternating but the motor didn't like it.
thanks
minimum injector open time
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Read the manual to see if your question is answered there before posting. Many users will not reply if the answer is already available in the manual.
If your question is about troubleshooting, configuration, or tuning, you MUST include your processor type (MS-I or MS-II) and code version in your post. If your question is about PCB assembly or modifications, you must also include the main board version number (1.01, 2.2 or 3.0). For tuning/troubleshooting questions, please attached a datalog and your MSQ file to your post.
If you have questions about MS1/Extra or MS2/Extra code configuration or tuning, please post them at www.msextra.com Such questions posted here will be moved to: a temporary MSextra sub-forum, where they will be removed after 7 days
The full forum rules are here: Forum Rules, be sure to read them all regularly.
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Bernard Fife
- Master Squirter
- Posts: 475
- Joined: Thu Oct 29, 2009 12:54 pm
Re: minimum injector open time
355vette,
Don't confuse opening time with pulse width. These are two different, but related things.
The opening time is meant to represent the time it takes to open the injector (i.e. the time between when the injector signal starts and it actually starts squirting fuel). This is typically 1.0 for a high-impedance injector, and around 0.7 to 0.9 for a low-impedance injector (including most TBI set-ups).
The idle pulse width is much more important with MS-I because it only has 0.1 millisecond injector pulse width resolution. Pulse widths under about 1.7 mean that the tuning occurs in large steps that may make it impossible to get just the right amount of fuel. See: http://www.megamanual.com/v22manual/mtune.htm#idlepw
MS-II has 100x better pulse width resolution, so the issue with idle pulse width has only to do with how accurate the injector open time is. That doesn't even matter, as long as you don't change the req_fuel, number of squirts, or anything like that.
So if you can tune the idle and cruise to work as you prefer, then don't worry about the low pulse width.
Lance.
Don't confuse opening time with pulse width. These are two different, but related things.
The opening time is meant to represent the time it takes to open the injector (i.e. the time between when the injector signal starts and it actually starts squirting fuel). This is typically 1.0 for a high-impedance injector, and around 0.7 to 0.9 for a low-impedance injector (including most TBI set-ups).
The idle pulse width is much more important with MS-I because it only has 0.1 millisecond injector pulse width resolution. Pulse widths under about 1.7 mean that the tuning occurs in large steps that may make it impossible to get just the right amount of fuel. See: http://www.megamanual.com/v22manual/mtune.htm#idlepw
MS-II has 100x better pulse width resolution, so the issue with idle pulse width has only to do with how accurate the injector open time is. That doesn't even matter, as long as you don't change the req_fuel, number of squirts, or anything like that.
So if you can tune the idle and cruise to work as you prefer, then don't worry about the low pulse width.
Lance.
"Never wrestle with pigs. You both get dirty and the pig likes it.” - George Bernard Shaw