I should of posted this thread in this category....&nbsp\\; Can anyone offer me any assistance.&nbsp\\; Thanks guys.
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https://www.hdforums.com/m_3521034/m...tm.htm#3521683

 

I think I am either seeing things or the chart says 26.65 In-hg. Where do you live in CA? If you live at sea level your tune is too lean.

 

Yes I live in California.&nbsp\\; The chart states 28.66 in- hg ... it is hard to read.&nbsp\\;
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Now at the risk of sounding stupid what does that mean?
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Thanks for the help.

 

Inches of Mercury. It is the atmospheric pressure in your current surroundings. I live at sea level. So on a good day it is around 30-30.5 When a storm front moves in, it might drop to 29.5 Same thing goes for claiming mountains. If you start out around sea level 30.2 and clime to altitude the Barometric pressure will drop. The higher the pressure the more air the bike will breath. The lower the pressure the less it will breath. Claiming to altitude also reduces the amount of oxygen that is in the air. A lot of SERT and PCIII ETC... tuning is performed at the wrong altitude for the given motorcycle. If a bike is tuned at 3000 feet it will run lean at sea level and vice versa. Google Barometric pressure and read about it. There are other&nbsp\\;factors involved with tuning like humidity and temps. My personal opinion is to only tune your bike at a slightly lower altitude from where you live, (granted the Dyno is Even calibrated correctly) on a nice sunny day with the temps above 80 and less than 50% humidity. Most of the systems are open loop and do not react lo changes in the atmosphere like the car you are driving.

 

Why? We're talking EFI (he has a 2008), not carb. If the measured pressure is correct, and the tune is done for that pressure, a change in pressure after the tune will be accounted for. It's one of the variables in the calculations the ECM does to determine the fuel required.

 

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More air needs more fuel, and vice versa, but if the system cannot sense the change in the airflow, the proper air/fuel ratio will not be provided. Since none of the systems used by Harley-Davidson use airflow sensing to establish the fuel mix, the fuel map needs to be altered to ensure a proper mix.
So what you are telling me is that you have a special HD that works better than everyone else's? I don't see mass air flow sensors Boro or wide band O2 on these things yet!

 

A MAP based system (Harley) and a MAF based system are doing the exact same thing: figuring out the mass of the air entering the engine. They just do it in different ways. MAF directly measures it. MAP uses the predefined VE table and corrects it using it's air pressure measurement. And yes, you have a pressure sensor. The P in MAP sensor stands for pressure. Same thing, just different way of doing it. Thus they both account for altitude.

 

We could argue our points till days end. I know you want to believe the MAP sensor is capable of performing miracles. It is still an out dated Speed Density System that needs improvement in my opinion. If the system worked as good as you are claiming, we would not have to load base maps and pay tuners to get it&nbsp\\;running acceptable. We would add our goodies and have faith that the MAP sensor is going to add the right fuel mix, timing adjustments and all would be well. The key words to this is Air flow! Not a guesstimate of the flow of air. As we all know, the current system only keeps it within an acceptable level. My point to Mike is I think the tuner set his bike up incorrectally. The current EFI system in HDs&nbsp\\;could be improved. But if they&nbsp\\; went to a plug and play systen, there would be no need for a SERT&nbsp\\;or a tuner at the dealer and HD would loose money! Or if we are going to&nbsp\\;beleave&nbsp\\;that a MAP and MAF do the same thing, Mike should have been able to add his pipes and the MAP sensor should have been able to sense the change in air flow so he wasted his money on the tuner to start with?

 

No, it wouldn't. A MAP based system (without wideband O2s) will never be able to do that. If you believe what you've just said, you don't have a firm understanding of how these systems work. A MAP based system must be told the air flow through the engine. Using the MAP sensor and other sensors, it calculates the mass of the air entering the engine. Having to have the air flow predefined is the reason you must tune it when you make changes, not because it doesn't do a good job.

We can agree on that.

You didn't read my post correctly. They do not do the same thing. They accomplish the same thing, but do it in different ways. The obvious drawback to the MAP system is you have to predefine the air flow, in other words, tune it. But once it's tuned correctly, it will correct for altitude.