Some pulse width confussion with setting

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luv2trade442
MegaSquirt Newbie
Posts: 8
Joined: Sat Sep 08, 2007 11:02 am

Some pulse width confussion with setting

Post by luv2trade442 »

I need some clarification on how to set a few things with megatune 2.25 and MS3.0
1. If i want to set the cranking pulse width to 3.6 just where do i set that? i see a cranking PW chart but the values run from maybe cold at -40 of 10.2 ms to hot a +160 and 3.0 ms. So when they say set the cranking PW to 3.6 and don't mention a temperature...i'm confussed.
2. About same question with prime pulse. I see the chart with the different temps and pulse widths, but not sure how to set it to 3.6 ms without a temp referance.
3. Idle pusle width....I am told an exact setup like my engine uses an idle pulse width of 1.261 ms so i guess i would add the 1.0 ms opening time for MS2 calculations and set it to 2.261 ms for the MS2 idle pulse width...but where??
4. Injections per engine cycle.... 2 squirt alternating.....it says to set it so engine idle pulse is more than 2.0 ms .....can i use the above idle pusle width of 1.261? isn't that going to be 1.0+ .63 = 1.63 ms each injection?
5. Isn't there somewhere it shows the running pulsewidth at running temp ?
THX much
1968 Hurst Olds 455
BBK 1000 CFM Tbody
32# Accell injectors
grippo
Site Admin
Posts: 286
Joined: Mon Feb 16, 2004 6:55 pm

Re: Some pulse width confussion with setting

Post by grippo »

luv2trade442 wrote:I need some clarification on how to set a few things with megatune 2.25 and MS3.0
1. If i want to set the cranking pulse width to 3.6 just where do i set that? i see a cranking PW chart but the values run from maybe cold at -40 of 10.2 ms to hot a +160 and 3.0 ms. So when they say set the cranking PW to 3.6 and don't mention a temperature...i'm confussed.

>> There are 2 options for this: 2-point or table. The 2 point option lets you specify a cranking PW at the lowest and highest of your coolant temperature table points and it interpolates in between. The second option allows you to put in CPWs for every temperature in case you want a nonlinear curve. The temperatures (10 of them) are the same ones you use for coolant vs warmup enrichment table.
You specify which option in one of the fuel menus on the left. If you specify 2-point, then there should be 2 CPWs on a nearby or same fuel menu, otherwise these will be greyed out and you will find the CPW vs temp table somewhere on the right under a tables menu. It is not possible to set a single CPW. If you saw this in the manual, it is just giving a rough idea of how large you want this at reasonable startup temperatures like 40-80 degF.

2. About same question with prime pulse. I see the chart with the different temps and pulse widths, but not sure how to set it to 3.6 ms without a temp referance.

>> same answer.
3. Idle pusle width....I am told an exact setup like my engine uses an idle pulse width of 1.261 ms so i guess i would add the 1.0 ms opening time for MS2 calculations and set it to 2.261 ms for the MS2 idle pulse width...but where??

>> There is no idle PW. Once you are past cranking rpm the ECU uses the VE table to calculate PW. A PW of 1.262 is very small - it won't give much if any fuel unless it is a very unusual and small injector.

4. Injections per engine cycle.... 2 squirt alternating.....it says to set it so engine idle pulse is more than 2.0 ms .....can i use the above idle pusle width of 1.261? isn't that going to be 1.0+ .63 = 1.63 ms each injection?


5. Isn't there somewhere it shows the running pulsewidth at running temp ?

>> There is a PW gauge that is standard on the PC interface. You can make a clt gauge by right clicking the mouse on a gauge you don't want and selecting CLT temp from the menu.


THX much
luv2trade442
MegaSquirt Newbie
Posts: 8
Joined: Sat Sep 08, 2007 11:02 am

Re: Some pulse width confussion with setting

Post by luv2trade442 »

Thanks much, that clears up alot. So, i guess i am sort of setting the pulse width or fine tuning it when i adjust the VE tables. Not much left to do but double check stuff and try starting the thing up. THX again
1968 Hurst Olds 455
BBK 1000 CFM Tbody
32# Accell injectors
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