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Where should AFR readings be for MPI 509
Been seeing some dark soot on my tips and started doing some testing. Picked up MEFI Burn and FAST Dual AFR setup. This is a 509 with around 500 hp at the prop on a 11K boat (real heavy). Saw a carb thread (Smitty's) and after posting but then realized again I should not have said anything. In any case I'm trying to figure out if there is any tuning I might try. Do plan to turn my code 44 flag OFF. Here are my readings
https://cimg5.ibsrv.net/gimg/www.off...bc63a81131.jpg |
Is nt the goal to be around 12-13 for most if not each engines? I thought so at least! |
You need to know what the load or vacuum is at the different rpms also.
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This is a single engine setup, so the one motor is really working hard with a B3 drive. I can put a vacuum gauge on but have not seen the vacuum readings before when dealing with AFR's. The O2 sensor is reading how well the fuel is burning to my understanding, so how does knowing the vacuum give more info ? Not saying its not good to know, just don't understand the correlation
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Originally Posted by AllDodge
(Post 4628978)
Been seeing some dark soot on my tips and started doing some testing. Picked up MEFI Burn and FAST Dual AFR setup. This is a 509 with around 500 hp at the prop on a 11K boat (real heavy). Saw a carb thread (Smitty's) and after posting but then realized again I should not have said anything. In any case I'm trying to figure out if there is any tuning I might try. Do plan to turn my code 44 flag OFF. Here are my readings
https://cimg5.ibsrv.net/gimg/www.off...bc63a81131.jpg Specifically in the 750 rpm band I would lean out to 13.5-13.8. The 1800-2400 rpm band the boat is transitioning from a displacement hull to a planing hull, hence a fairly high load (MAP). You might pull a little fuel, and I mean a little fuel around 1800 but only if knock is under control. 2400 rpm is rich for my taste. I'd shoot for 12.5 -12.8. The rest looks fair to me. Splitting hairs if you want to change things. Don't touch the decel range. They will virtually always show rich unless you really shrink the BPW in the 40kPa or less column(s) which I don't recommend. |
Appreciate your thoughts
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I expected a stock Merc tune to be more in the 11s. That’s a better map than I would’ve guessed. |
It isn't stock, it was tune by Eddie a few years ago. Since then I have stripped the hull and epoxy painted
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Originally Posted by Trash
(Post 4629027)
You aren't out of line drastically in any regime. I would tweak things a little if so inclined.
Specifically in the 750 rpm band I would lean out to 13.5-13.8. The 1800-2400 rpm band the boat is transitioning from a displacement hull to a planing hull, hence a fairly high load (MAP). You might pull a little fuel, and I mean a little fuel around 1800 but only if knock is under control. 2400 rpm is rich for my taste. I'd shoot for 12.5 -12.8. The rest looks fair to me. Splitting hairs if you want to change things. Don't touch the decel range. They will virtually always show rich unless you really shrink the BPW in the 40kPa or less column(s) which I don't recommend. |
Originally Posted by AllDodge
(Post 4629003)
This is a single engine setup, so the one motor is really working hard with a B3 drive. I can put a vacuum gauge on but have not seen the vacuum readings before when dealing with AFR's. The O2 sensor is reading how well the fuel is burning to my understanding, so how does knowing the vacuum give more info ? Not saying its not good to know, just don't understand the correlation
If you have mefiburn use the scanner to see how much load you are putting on the engine with the MAP readings. Very valuable tool. |
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