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Idle pulse width - How do you calculate it

Posted: Mon Oct 06, 2008 8:19 pm
by drholl
Trying to estimate “Idle pulse width”.
MS-2
V3
2.886
MT2.25

In the documentation (http://www.megamanual.com/v22manual/mtune.htm#howto) it says to get the required fuel.
(OK, no problem.)
It states that it should be less than @ 12 to 15 ms.
(that’s OK too.)
And the idle pulse width should be greater than @2 ms. idle pulse width???

“Injections per Engine Cycle is set the number of squirts you want per engine cycle. You want this to be set so that your idle pulse width is no less than 2.0 ms, if possible, and your Req Fuel is less than 12-15 milliseconds, but more than 8 milliseconds.” Mine's 10.4 or so. (350 Chevrolet V8 with Chevy 454 CI (7.4 Liter) Throttle Body Injection.)

Idle pulse width? How do I estimate the idle pulse width? In my injection control setup the top number is 5.2 ms and the bottom number is 10.4. Do I take the 5.2 and multiply it by an estimated (guess) VE of about .25-.30 to get 1.3? If this is the proper procedure then I’ll recalculate how I want my injectors to fire. I would like to avoid flooding the engine with many of my friends watching. I’m going to help them fuel inject their cars.

I'm using an MS-II daughtercard. Would an idle pulse width of 1.3ms be too short?
Thanks in advance

Thanks Holl

Re: Idle pulse width - How do you calculate it

Posted: Tue Oct 07, 2008 4:36 pm
by drholl
Thank you very much, Lance.
I appreciate the response and your time.

I almost couldn't believe it, it started right up. :D
A lot rich though, and ya know, they run really rich when you've forgotten to hook up the MAP sensor. :roll: Oops on my part.

Holl