mass air flow sensor location
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:agree:with KIT, way down in there.
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There is no mass air flow (MAF) sensor on the GL1800. The MAP sensor is a Manifold Air Pressure sensor.
I don't know if the ECM in the Wing uses Alpha N or Speed Density to calculate fuel mixture and it's impossible to say for sure without downloaded the ECM and cracking into the code to see. Some manufactures even use a combination of the two methods depending on engine RPM. The MAP sensor output is used in both types of calculations to help derive airflow.
I don't know if the ECM in the Wing uses Alpha N or Speed Density to calculate fuel mixture and it's impossible to say for sure without downloaded the ECM and cracking into the code to see. Some manufactures even use a combination of the two methods depending on engine RPM. The MAP sensor output is used in both types of calculations to help derive airflow.
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Fred,
I'm really surprised to learn that the GL1800 does not use a MAF. Never gave it much thought before today.
Everything I've ever learned or studied about speed density/MAP systems in car engines indicated that they have mostly all been replaced with MAF systems since a MAF actually provides a direct measurement of the air flow coming into the engine. This, as compared with the older methods, speed density included, that rely on a calculated estimate.
That said, one of the main reasons engine tuners like a MAF system on cars is that you can change things like intake manifolds, exhaust systems, power adders such as turbos and superchargers, and the MAF system can compensate for all of those changes pretty much without problems. If you make similar changes on a speed density system, you'd end up with a car that runs pretty badly. Been there done that back when I did a lot of work on cars myself.
I guess that the Honda engineers figured that no one would be making those kind of changes on a bike. Plus, if you have a MAF sensor, you always have the issue of the heated wire element and the unheated base line wire element in the sensor getting dirty and needing cleaning, which on GL1800 would require considerable disassembly since a MAF has to be located directly in the air intake plumbing.
Learn something new every day. Thought sure there would be a MAF on our bikes. Duh!
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I think it just depends on the designer of the engine and his budget constraints. Not having a MAF sensor saves cost. Most motorcycle engines don't have MAF sensors on them, and the ECU's on most bikes are still extremely simple when compared to modern day automotive ECU's. Most autos also have two O2 sensors on them, one before and one after the CAT, but most bikes only have one 02 sensor, if they even have one at all. I think its all about cost. Motorcycle engines are still pretty basic in terms of electronic controls, though that is slowly starting to change. Motorcycle manufactures have never really felt a need to push the envelope on gas mileage numbers, and this is what has really driven auto manufactures to invest in better fuel control methods. However, there are quite a few cars running around now that don't have MAF sensors on them either, and just rely on speed density calculations and/or use static correction tables and alpha N.
I agree a MAF sensor makes (non-boosted) modifications much easier since changes to things that impact airflow will (for the most part) get automatically compensated for so you don't have to remap the fuel.
The up and coming method for modifying motorcycles is to download the ECU and modify the fuel tables in it and then reflash the ECU with the new values. This is starting to become more popular, and in my opinion it is a better way to go than adding a piggyback device like a Power Commander. Being able to reflash the ECU also enables you to adjust the ignition timing tables and other parameters (like secondary throttle plate maps, if so equipped, or speed and RPM limiters) and so it can open up a whole host of possibilities that a piggyback fuel controller can't do.
I agree a MAF sensor makes (non-boosted) modifications much easier since changes to things that impact airflow will (for the most part) get automatically compensated for so you don't have to remap the fuel.
The up and coming method for modifying motorcycles is to download the ECU and modify the fuel tables in it and then reflash the ECU with the new values. This is starting to become more popular, and in my opinion it is a better way to go than adding a piggyback device like a Power Commander. Being able to reflash the ECU also enables you to adjust the ignition timing tables and other parameters (like secondary throttle plate maps, if so equipped, or speed and RPM limiters) and so it can open up a whole host of possibilities that a piggyback fuel controller can't do.
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:agree:
Speed density systems usually will develop more power than a MAF system on the same engine (at the expense of fuel economy). This was true of the Mustangs when they switched to mass air metering in the early 80's. The speed density cars where .2 seconds quicker than the mass air cars in the quarter mile, apples to apples. SD systems are cheaper to implement and more reliable IMO. Using a wideband O2 they can be very accurate in getting the lambda correct, even with forced induction and/or big cams. But for a motorcycle that doesn't need to conform to gov fuel economy mandates or emission controls and has very few power upgrade options, speed density fits the bill perfectly.
As stated above, speed density cannot take very many modifications (especially cams and forced induction) without re-mapping the ECM. However, most of the serious race guys actually go back to speed density with an aftermarket system like the F.A.S.T. XFI 2 or similar. Many MAF ECM's cannot handle extreme engine VE changes either, even with programmable add-on chips or reflashing. I'm going through this exact issue with my race car right now. Can't get big enough high impedance injectors, and the ECM doesn't have enough parameters to allow the engine to run optimally with the displacement, cam and supercharger changes. The XFI system solves all of that.
If you're interested or bored: http://www.fuelairspark.com/
Speed density systems usually will develop more power than a MAF system on the same engine (at the expense of fuel economy). This was true of the Mustangs when they switched to mass air metering in the early 80's. The speed density cars where .2 seconds quicker than the mass air cars in the quarter mile, apples to apples. SD systems are cheaper to implement and more reliable IMO. Using a wideband O2 they can be very accurate in getting the lambda correct, even with forced induction and/or big cams. But for a motorcycle that doesn't need to conform to gov fuel economy mandates or emission controls and has very few power upgrade options, speed density fits the bill perfectly.
As stated above, speed density cannot take very many modifications (especially cams and forced induction) without re-mapping the ECM. However, most of the serious race guys actually go back to speed density with an aftermarket system like the F.A.S.T. XFI 2 or similar. Many MAF ECM's cannot handle extreme engine VE changes either, even with programmable add-on chips or reflashing. I'm going through this exact issue with my race car right now. Can't get big enough high impedance injectors, and the ECM doesn't have enough parameters to allow the engine to run optimally with the displacement, cam and supercharger changes. The XFI system solves all of that.
If you're interested or bored: http://www.fuelairspark.com/
That is the key to it all right there. The Goldwing's ECM is very rudimentary, and it doesn't need to be any more complex than it is. Considering that the 1800 was meeting CARB standards 8 years into the future when it was introduced, there was no need to invest in a complex ECM. The ECM we have probably cost all of $25 to make. A portable CD player has more electronics in it.
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