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Old 10-02-2015, 09:33 PM   #1
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Default Pulse width values. Percentage or milliseconds

I have a freshly installed MS3 I'm starting the process of tuning. The car starts and runs on the base program but it starts poorly, very long crank time and stalls after start.

I intend to begin by adjusting cranking pulse width but I'm confused by the different terms used in Tuner Studio vs. the Megamanual for pulse width values. Tuner Studio uses a value based on a percentage and the manual uses values based on milliseconds.

Any idea how I jive the two?
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Old 10-02-2015, 11:14 PM   #2
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Do you have the priming pulse feature enabled? It gives a shot of fuel when the ignition switch is turned on, prior to cranking.
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Old 10-03-2015, 10:33 AM   #3
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The megamanual is for MSI. You have an MS3.

Manuals for Megasquirt-3 - Megasquirt EFI
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Old 10-03-2015, 02:29 PM   #4
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Yup, the priming pulse is enabled. I'm messing with it a bit this morning and I'm beginning to think my problem lays somewhere else. The engine actually starts reasonably well but dies quickly. I was attacking the problem as after start fuel enrichment but I think I'm loosing fuel pressure, as though the fuel pump isn't getting a signal immediately after start up. That's the direction I'm headed now.
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Old 10-03-2015, 02:29 PM   #5
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your ASE is set up correctly?
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Old 10-03-2015, 02:57 PM   #6
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Thanks. That's a help.
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Old 10-03-2015, 02:59 PM   #7
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Yes. ASE is the next step.
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Old 10-03-2015, 03:02 PM   #8
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I'd have to say that I don't know if my ASE is set up correctly 'cause that's an acronym I don't recognize.
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Old 10-03-2015, 06:58 PM   #9
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After Start Enrichment. You mentioned it in post #4.
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Old 10-03-2015, 07:51 PM   #10
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Ah, OK. I'll get hip and inside to all the acronyms and abbreviations eventually.
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Old 10-05-2015, 12:56 AM   #11
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this may help:

The primary map you're tuning in a megasquirt is the VE table. It IS a percentage.. of the amount of fuel your engine needs to complete a single cycle at 14.7 AFR at 100kPa and 100% volumetric efficiency (and some other fixed points).

The engine will be some deviation (above or below) from that value for the whole range of operation. The VE table is tuned to match that deviation with 100% meaning no deviation. And ultimately you don't care what the milliseconds are as long as the engine performs as you expect (AFR, EGT, power, fuel consumption, etc).

milliseconds are, however, helpful for tuning other maps.
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Old 10-07-2015, 01:11 PM   #12
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Quote:
Originally Posted by y8s View Post
this may help:

The primary map you're tuning in a megasquirt is the VE table. It IS a percentage.. of the amount of fuel your engine needs to complete a single cycle at 14.7 AFR at 100kPa and 100% volumetric efficiency (and some other fixed points).

The engine will be some deviation (above or below) from that value for the whole range of operation. The VE table is tuned to match that deviation with 100% meaning no deviation. And ultimately you don't care what the milliseconds are as long as the engine performs as you expect (AFR, EGT, power, fuel consumption, etc).

milliseconds are, however, helpful for tuning other maps.
You rock. Thanks for the explanation.
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