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Pulse widths for injectors

Old 08-27-2019 | 11:10 AM
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Originally Posted by scippy
So my engines are 9 :1 comp. & if there tuned to 89 octane what damage would occur by continuing to use AV gas?.......burnt exhaust valve?......using it was a decision simply for it's shelf life.
I still have 50 gals left from it's initial fill up ...boat has only been used 5 hours since buying it........maybe a dumb reason to have used AV gas in the first place, but I'm sure auto gas would have
turned to varnish by now!........If it's too complicated to tune for AV gas with AS&M EFI's (not sure about ECM).....Thought the remedy would be pulse widths for injectors to compensate for AV
then auto gas would be less complicated!
What ECM are you using?

The only way to adjust the BPW is by tuning.

If you are tuned for 89, and run AV gas it will be 'rich'. If it is tuned for AV gas and you run 89, it will run lean.

If you are concerned I'd just mix your remaining AV gas with 89/91 till its gone.
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Old 08-27-2019 | 11:41 AM
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Trash I believe it's the opposite ...9:1 and tuned for 89 octane motors are running very lean with AV..........your suggestion is best advice fill w/91 and run. Can't answer about ECM I'm not sure.
articfriends yes shelf life concern & to do all this end around like zz28zz said, sad story in the end!
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Old 08-27-2019 | 07:10 PM
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Originally Posted by scippy
Trash I believe it's the opposite ...9:1 and tuned for 89 octane motors are running very lean with AV..........your suggestion is best advice fill w/91 and run. Can't answer about ECM I'm not sure.
articfriends yes shelf life concern & to do all this end around like zz28zz said, sad story in the end!
My apologies if this was in error. I looked at my tables and had it backwards. I should not have equated VP110 to AV gas as well. I've tested with VP110 and not AV gas.
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Old 08-27-2019 | 09:40 PM
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Jesus, just use the 50 gallons in a mower of something . why in the world would you change your entire tune and take a chance of ****ing up 2 engines over 50 gallons in gas?!
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Old 08-27-2019 | 11:21 PM
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Pretty blunt, but great advice!
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Old 08-28-2019 | 07:40 AM
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Another thought too, most tunes are NOT not very edge of burndown by any means, ie, if I tune a NA motor at 12.2 afr, guy changes fuel and it runs 12.5 its not going to just melt a piston. Theres always some margin in most tunes, I think your putting way too much thought into this, Smitty
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Old 08-28-2019 | 09:59 PM
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Originally Posted by articfriends
Another thought too, most tunes are NOT not very edge of burndown by any means, ie, if I tune a NA motor at 12.2 afr, guy changes fuel and it runs 12.5 its not going to just melt a piston. Theres always some margin in most tunes, I think your putting way too much thought into this, Smitty
I agree Smitty, way too much thought!.......I'm going to blend auto gas with the remaining AV gas and go on my merry way.
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